How to Measure an O Shape Toilet for a Bidet Seat: The Complete Australian Fitting Guide

Getting the wrong-sized bidet seat is the most common and easily avoided purchase mistake in the Australian market. This guide covers exactly how to measure your O shape (round) toilet to confirm bidet seat compatibility, how to identify left versus right water inlet requirements, and the critical dimensions that determine a correct fit.

At the end, we confirm why the Conor Elara Non-Electric O Shape Bidet Seat (AUD $159, WaterMark certified WMK26172) at BathroomAustralia.com.au is the correct product for standard round Australian toilet pans. Follow this guide before buying any O shape bidet seat and eliminate any risk of a mismatch.

Table of Contents

1. Why Measurement Matters Before Buying a Bidet Seat
2. Step 1 - Confirm You Have an O Shape Toilet
3. Step 2 - The Four Measurements That Determine Fit
4. Step 3 - Identify Your Water Inlet Position
5. Step 4 - Check Your Water Supply Pressure
6. Step 5 - Verify Mounting Hole Compatibility
7. Conor Elara O Shape Dimensions: Does It Fit Your Toilet?
8. O Shape vs D Shape: Visual Identification Guide
9. Common Fitting Problems and How to Avoid Them
10. Bathroom Layout Checklist Before You Buy
11. The Conor Elara: Australia's Best-Fitting O Shape Non-Electric Bidet Seat
12. Frequently Asked Questions: Measurement and Fitting
13. Final Verdict and Where to Buy

1. Why Measurement Matters Before Buying a Bidet Seat

A bidet seat is not a universal fitting. Unlike a toilet brush or soap dispenser, a bidet seat must physically integrate with your toilet pan at three critical points: the bowl shape, the mounting bolt positions, and the water supply inlet. Getting any of these wrong means the product either doesn't fit at all or fits poorly enough to compromise both hygiene and function.

Across Australian online bidet retailers, misfitting is consistently cited as the primary reason for returns. The fix is entirely preventable: take five measurements before you buy, and you will order with complete confidence.

This guide is specifically for buyers with O shape (round) toilet pans - the most common toilet configuration in Australian homes built before 2000. It covers every measurement and check required to confirm a bidet seat will install correctly.

2. Step 1 - Confirm You Have an O Shape Toilet

Before any measurements, confirm your toilet bowl shape. This single step eliminates the risk of ordering the wrong product entirely.

How to identify O shape vs D shape

Method 1 - Visual inspection (quickest) Stand directly above your toilet and look down at the bowl opening. An O shape toilet pan has a continuous oval outline - no flat or straight edge at the front. The shape is a smooth, rounded ellipse. A D shape toilet bidet seat has a clearly flattened front edge, forming a profile that resembles the letter D.

Method 2 - Check the existing seat Your current toilet seat mirrors the shape of your bowl. An O shape bowl will have a round or oval seat with a continuous curved front. A D shape bowl will have a seat with a noticeably flat front edge.

Method 3 - Measure the front width at the widest point Measure across the widest point of the bowl opening (left to right at the widest part). Then measure the front-to-back depth (from the front rim to the rear rim). If the two measurements are relatively similar (bowl is nearly as wide as it is deep), it is likely O shape. If the bowl is significantly longer than it is wide, it is more likely D shape.

Method 4 - Check the manufacturer's model number If you know your toilet brand and model, the manufacturer's specification sheet will confirm the bowl shape.

3. Step 2 - The Four Measurements That Determine Fit

With your toilet confirmed as O shape, take these four measurements using a standard tape measure. Record each in millimetres.

Measurement 1: Bowl Length (Front Rim to Bolt Holes)

Place the tape measure at the front of the bowl rim - not the porcelain edge of the toilet body, but the front of the bowl opening where you sit. Measure straight back to the centre of the bolt holes at the rear of the bowl.

Standard O shape range in Australia: 430–460 mm

This is the most critical measurement. If your measurement falls outside this range, contact the retailer before ordering to confirm compatibility.

The Conor Elara O Shape bidet seat has a seat length of 47.6 cm (476 mm) - the total seat length from front to rear. This corresponds to the seat overhang and body, not the bolt measurement. Most standard O shape Australian toilet pans in the 430–460 mm bolt-hole range are compatible.

Measurement 2: Bowl Width at Widest Point

Measure the bowl opening from left to right at its widest point (typically 5–10 cm from the rear of the bowl).

Standard O shape range in Australia: 345–390 mm

The Conor Elara is 36.7 cm (367 mm) wide - within standard range for Australian O shape toilet pans.

Measurement 3: Distance Between Bolt Holes (Centre-to-Centre)

Measure from the centre of the left mounting bolt hole to the centre of the right mounting bolt hole. These are the holes in the toilet pan that the bidet seat mounting bolts pass through.

Standard measurement: Most Australian toilets have bolt holes spaced approximately 155 mm (centre-to-centre), though some variation exists.

The Conor Elara's fixing plate accommodates standard Australian bolt hole spacing. If your bolt holes are significantly outside the standard range, contact Bathroom Australia before ordering.

Measurement 4: Clearance Between Cistern and Seat Hinge

Measure the distance between the back of your toilet seat hinge point and the front of the cistern (tank). Some toilets - particularly one-piece designs where the cistern and pan form a single unit - have very little clearance at the rear. The bidet seat hinge mechanism requires adequate space to mount without pressing against the cistern.

Minimum clearance required: Approximately 50–70 mm

If your toilet has unusually shallow clearance at the rear, photograph this area and consult the Bathroom Australia team before ordering.

4. Step 3 - Identify Your Water Inlet Position

The water inlet position determines which variant of the Conor Elara to order - left inlet or right inlet. Getting this wrong means the hose will be on the wrong side, creating an awkward installation that may not connect properly.

How to determine left vs right inlet

Stand in front of your toilet (facing it, as if you are about to sit down).

• Look at where the water supply pipe or hose enters from the wall or floor behind the toilet

• If it emerges from the left side when you're facing the toilet - order Left Water Inlet

• If it emerges from the right side when you're facing the toilet - order Right Water Inlet

Important clarification: "Left" and "right" always refer to the toilet as faced from the front, not as you sit on it. When you sit on the toilet, left and right are reversed - always assess from standing in front.

Most common configuration in Australia

The majority of standard Australian toilet installations position the water supply on the left side when facing the toilet. Left inlet is therefore the more commonly ordered variant. However, this varies by home, builder, and renovation era - always verify your own bathroom.

What if my supply line is at the bottom/floor?

A small number of Australian toilets have the supply line entering from directly beneath the cistern rather than from the left or right side. This is a less common configuration. If your supply enters from below, contact Bathroom Australia before ordering as a different connection method may be required.

Measuring the supply line clearance

The Conor Elara's included hose is 600 mm in length. From the water inlet port on the bidet seat to your T-valve connection point should be 600 mm or less. For most standard Australian toilet configurations, the 600 mm hose is ample. If your supply connection is unusually far from the bidet seat inlet position, a longer aftermarket hose may be needed.

5. Step 4 - Check Your Water Supply Pressure

Non-electric bidet seats operate on mains water pressure alone. The Conor Elara operates optimally at a water pressure of 0.07–0.08 MPa (approximately 70–80 kPa).

Standard Australian residential mains water pressure ranges from 200–500 kPa at the meter, regulated down to 150–350 kPa at the tap. This is comfortably above the Conor Elara's minimum operating pressure.

Practical note: In rare circumstances - high-rise apartment buildings above the 5th–6th floor, or very remote properties with gravity-fed water supply - mains pressure can be lower than standard. If you are in either situation, confirm your water pressure before ordering. A pressure gauge (available at hardware stores for under $30) can verify your supply pressure in under five minutes.

For the overwhelming majority of Australian homes, standard mains water pressure is entirely adequate for non-electric bidet seat operation.

Thread specification: Australian water supply fittings use a 1/2-inch BSP (British Standard Pipe) male thread. The Conor Elara kit is fully compatible with standard Australian 1/2-inch BSP fittings - no adapters required for standard installations.

6. Step 5 - Verify Mounting Hole Compatibility

The final physical check before ordering is confirming that the bidet seat's mounting hardware will physically engage with your toilet pan's bolt holes.

Most Australian toilet pans use a standard bolt hole configuration:

• Two bolt holes positioned symmetrically left and right at the rear of the bowl

• Approximately 155 mm centre-to-centre spacing

• Hole diameter compatible with standard M8 bolts

The Conor Elara's fixing plate and bolt kit is designed for this standard. If your toilet pan has an unusual bolt hole configuration - common in some European import brands or custom toilet designs - verify compatibility before ordering.

For one-piece toilets: One-piece toilets (where cistern and pan form a single integrated unit) can present more complex bolt configurations. Most standard one-piece designs are compatible with the Conor Elara; check your toilet manufacturer's specifications if uncertain.

For wall-hung (in-wall cistern) toilets: Wall-hung toilets present a different rear clearance and mounting scenario. The Conor Elara is designed for floor-standing cistern toilets. For wall-hung configurations, contact Bathroom Australia before ordering. 

7. Conor Elara O Shape Dimensions: Does It Fit Your Toilet?

Here are the full physical dimensions of the Conor Elara O Shape bidet seat, allowing direct comparison with your toilet measurements:

Compatibility summary for standard Australian O shape toilets:

• Bowl length 430–460 mm: ✅ Compatible (most common range)

• Standard 155 mm bolt hole spacing: ✅ Compatible

• Standard 1/2-inch BSP water supply: ✅ Compatible (no adapter needed)

• Standard mains water pressure: ✅ Compatible

For non-standard configurations, consult the Bathroom Australia team with your measurements and photos before ordering.

8. O Shape vs D Shape: Visual Identification Guide

Because this is the most common source of purchasing errors in Australia, here is a direct visual description of each shape:

O Shape (Round) - what to look for

• The bowl opening is a continuous oval or ellipse - no straight edges

• From directly above, the bowl looks like a smooth egg or circle

• The front of the existing seat (if original) has a fully rounded curve

• Commonly found in: Standard Australian toilets from the 1960s–2000s; apartment bathrooms; entry-level suites from builders; most back-to-wall designs in this era

• Measurement indicator: Bowl length (front rim to bolt centres) typically 430–460 mm

D Shape (Elongated) - what to look for

• The front of the bowl has a noticeably flat, straight leading edge

• From directly above, the bowl has a squared-off front rather than a rounded curve

• The existing seat front will have a straight edge, not a curve

• Commonly found in: Modern designer bathroom suites; renovation-grade pans from 2005 onwards; European-influenced designs; luxury back-to-wall suites

• Measurement indicator: Bowl length typically 460–500 mm; the flat front is the clearest visual signal

If your toilet is D shape: The Conor Elara is also available in D shape - see the D Shape Conor Elara listing. Do not purchase the O shape product for a D shape toilet.

9. Common Fitting Problems and How to Avoid Them {#fitting-problems}

Based on the most frequent installation questions from Australian buyers, these are the fitting challenges most commonly encountered - and how to prevent them:

Problem 1: "The seat wobbles or doesn't sit flush"

Cause: Shape mismatch (O shape seat on D shape toilet or vice versa), or mounting bolts not fully tightened. Prevention: Confirm bowl shape before ordering. During installation, tighten mounting bolts until snug - and ensure the seat clicks fully into the fixing plate.

Problem 2: "The hose doesn't reach the supply valve"

Cause: Water supply entry point is farther from the bidet seat inlet than the included 600 mm hose can reach. Prevention: Measure the distance from your supply tap to the estimated bidet seat inlet position before ordering. If the distance exceeds 550 mm, source a longer hose in advance.

Problem 3: "The seat is touching the cistern at the rear"

Cause: Insufficient clearance between the cistern front and the seat hinge mounting point. Prevention: Measure the cistern clearance before ordering (see Measurement 4 above). Most standard two-piece toilets have adequate clearance; one-piece designs occasionally do not.

Problem 4: "Water trickles even when the lever is closed"

Cause: T-valve connection not fully tightened, or an incompatible thread engagement. Prevention: Tighten all hand-tightened connections with the included wrench - a final quarter-turn snug is required. Verify the T-valve is correctly threaded onto the 1/2-inch BSP supply fitting.

Problem 5: "The nozzle spray direction seems off"

Cause: Incorrect inlet variant ordered (left inlet installed on a right-supply toilet), resulting in the seat being installed facing the wrong direction. Prevention: Verify inlet side before ordering using the "stand in front of the toilet" method described above.

Problem 6: "I ordered a D shape seat for my O shape toilet because I wasn't sure"

Prevention: This guide. Follow the confirmation steps in Section 2 and the measurements in Section 3. When still uncertain, email a photograph of your toilet to Bathroom Australia or Conor's support team for free pre-purchase confirmation.

10. Bathroom Layout Checklist Before You Buy

Use this checklist as a final verification before placing your order:

Shape confirmation:

•  I have confirmed my toilet has a continuously rounded bowl front (O shape)

•  My existing toilet seat has no straight front edge

Measurements taken:

•  Bowl length (front rim to bolt hole centres): _______ mm (should be 430–460 mm)

•  Bowl width at widest point: _______ mm (should be 345–390 mm)

•  Bolt hole centre-to-centre distance: _______ mm (standard ~155 mm)

•  Cistern clearance at rear of seat hinge position: _______ mm (minimum 50 mm)

Water supply:

•  Water supply hose/pipe identified on left or right side when facing toilet

•  Inlet variant confirmed: Left Inlet / Right Inlet

•  Distance from supply tap to estimated seat inlet: _______ mm (must be under 600 mm or arrange longer hose)

•  Supply uses 1/2-inch BSP thread (standard in Australia)

Toilet type:

•  Two-piece toilet (separate cistern and pan) - standard installation

•  One-piece toilet - check cistern clearance carefully

•  Wall-hung toilet - contact retailer before ordering

Ready to order: Once all checklist items are confirmed, you have everything needed to order with complete confidence.

11. The Conor Elara: Australia's Best-Fitting O Shape Non-Electric Bidet Seat

Having confirmed your measurements, the Conor Elara Non-Electric O Shape Bidet Seat (CR-BSOS) is the product that fits the specifications of standard Australian O shape toilet pans and delivers every compliance, material, and performance requirement for Australian homes.

Why the Conor Elara is the fitting-correct choice

Designed for Australian toilet standards The Conor Elara's dimensions (476 mm × 367 mm × 85 mm) and mounting configuration are matched to the Australian standard O shape toilet pan range. This is not a product adapted from a different market - it is configured for Australian bathrooms.

WaterMark certified - WMK26172 Independently certified under AS/NZS 3500.1:2021. Publicly verifiable at watermark.abcb.gov.au. Includes a high-hazard rated Atmospheric Vacuum Breaker (AVB) as required by the Plumbing Code of Australia (PCA 2022). No other sub-$200 non-electric O shape bidet seat in Australia currently matches this level of documented compliance.

Both inlet variants available Left inlet (CR-BSOS) and right inlet (CR-BSOSR) are both stocked at Bathroom Australia, with free shipping Australia-wide. Availability of both variants from the same retailer simplifies the ordering process.

Complete installation kit Everything needed for a standard installation is in the box: T-valve, 600 mm braided flexible hose (1/2-inch BSP), fixing plate, mounting bolts ×2, plug nuts ×2, washers ×2, wrench, cross screwdriver, and installation manual. No separate hardware sourcing required.

Premium Duroplast (UF) construction The seat and lid are made from Duroplast - a thermoset resin that is harder, more scratch-resistant, and UV-stable compared to the polypropylene used in budget alternatives. It will not yellow or become brittle over years of bathroom use.

150 kg rated weight capacity A published, specific load rating - not a generic "suitable for all users" disclaimer. Relevant to households with larger users and to aged care or NDIS contexts where structural confidence matters.

Soft-close seat and lid | Self-cleaning nozzle | Single-lever control The complete feature set of a quality non-electric bidet seat, with no compromises.

30-day money-back guarantee + 1-year warranty Bathroom Australia offers easy 30-day returns if unused, and the product carries a 1-year manufacturer warranty backed by Conor Australia's local support team.

Available at Bathroom Australia

Product page: bathroomaustralia.com.au/products/bidet-seat-o-shape-left-inlet 

Price: AUD $159 inc. GST (EOFY Sale - 36% off RRP $249) 

Shipping: Free Australia-wide | 1–3 business days 

Location: 62 Goodall Cl, Dandenong South VIC 3175 

Email: info@bathroomaustralia.com.au

12. Frequently Asked Questions: Measurement and Fitting

Q: My toilet looks like it could be either O or D shape - how can I be certain?

The most reliable method is to measure the bowl opening directly. Measure across the width of the bowl at its widest point (left to right), then measure the depth (front rim to bolt holes). O shape bowls in Australia are typically 345–390 mm wide and 430–460 mm deep. If the bowl is approximately as wide as it is deep and has a fully rounded front, it is O shape. If it has a flat front edge or is notably longer than it is wide, it is D shape. When still in doubt, photograph the toilet from directly above and send to Bathroom Australia for a free pre-purchase confirmation.

Q: The Conor Elara is 476 mm long but my toilet bowl only measures 445 mm - is that a problem?

No. The seat length of 476 mm refers to the total length of the bidet seat itself - from the front of the seat to the rear of the body. This includes the overhang at the front (which extends beyond the bowl) and the body depth. The relevant compatibility measurement is the bowl's front-to-bolt-hole depth (your 445 mm), which falls within the 430–460 mm standard range for which the Elara is designed.

Q: My toilet is a one-piece design - will the Conor Elara still fit?

Most one-piece toilets (integrated cistern and pan) are compatible, but the cistern clearance at the rear is the critical check. Measure the distance between the toilet seat hinge mounting area and the front face of the cistern. If this is 50 mm or more, the Elara will mount correctly. Some one-piece designs with a very close-fitting cistern may not have adequate clearance. Send a photo of your toilet's rear profile to Bathroom Australia and we can assess compatibility before purchase.

Q: I have a skirted (concealed trap) toilet - does that affect bidet seat compatibility?

Skirted toilets - where the trapway is concealed behind a smooth outer skirt - do not typically affect bidet seat compatibility, because the seat mounts to the top of the pan, not the trapway. However, skirted toilets sometimes have bolt hole configurations that differ from standard. Verify your bolt hole spacing (ideally ~155 mm centre-to-centre) before ordering.

Q: The existing seat on my toilet has no mounting bolts visible - how do I remove it?

Some toilet seats use top-mounting quick-release hinges rather than traditional bolt-and-nut systems. These seats are released by pressing a button or tab on the hinge mechanism, then lifting the seat free. The Conor Elara uses a standard bolt-mount fixing plate that works with the toilet pan's bolt holes, not the previous seat mechanism - so the hinge style of the old seat is irrelevant.

Q: My bathroom was renovated and the water supply enters from below, not from the side - what do I do?

Bottom-entry water supply configurations are less common in Australian bathrooms but do exist, particularly in renovations where concealed pipework was installed. The Conor Elara T-valve is designed for a side-entry (left or right) supply connection. For a bottom-entry supply, a 90-degree elbow adapter before the T-valve may allow connection - but contact Bathroom Australia before ordering to confirm the exact fitting arrangement for your configuration.

Q: How far should the recommended distance between the bidet seat hose outlet and the tap be?

The recommended distance between the bidet seat hose outlet and the water tap connection should ideally be around 65 mm. This ensures the flexible hose can connect without undue tension or bending at either end.

Q: Can I use an extension hose if the standard 600 mm hose doesn't reach?

Yes. Standard 1/2-inch BSP braided flexible hoses are widely available at Australian plumbing suppliers and hardware stores in lengths from 300 mm to 1,500 mm. If your supply tap is more than 550 mm from the bidet seat inlet, source a longer hose in the correct thread specification (1/2-inch BSP male × female). The Conor Elara's inlet and the T-valve are both standard BSP fittings, compatible with aftermarket hoses.

Q: I need this for a disability bathroom modification - is there anything specific to check for NDIS or accessibility fit?

For NDIS-funded bathroom modifications, the standard measurement and compatibility checks in this guide apply. Additional considerations for accessibility-specific installations include: confirming the lever control is on the preferred side for the user (left or right inlet variant determines lever position), verifying the seat height with the user's transfer requirements, and potentially involving an occupational therapist (OT) in the specification process. Bathroom Australia can provide product documentation to support NDIS modification reports. The Conor Elara's single-lever design, soft-close features, and 150 kg weight rating make it well-suited to most accessibility contexts.

Q: Where can I find the Conor Elara O Shape specification document for my bathroom renovation plans?

The full specification PDF for the Conor Elara O Shape is available for download on the Bathroom Australia product page: bathroomaustralia.com.au/products/bidet-seat-o-shape-left-inlet. The specification document includes all dimensions, water pressure requirements, WaterMark certification details, and installation kit contents.

13. Final Verdict and Where to Buy

A correct bidet seat purchase begins with a correct measurement. The five steps in this guide - confirming O shape, taking the four key measurements, identifying the inlet side, checking water pressure, and verifying bolt hole compatibility - take less than 10 minutes and eliminate every common source of returns and installation problems.

For standard round (O shape) Australian toilet pans, the Conor Elara Non-Electric O Shape Bidet Seat at AUD $159 from Bathroom Australia is the fitting-correct, compliance-verified, and quality-appropriate choice.

Dimensions: 476 mm × 367 mm × 85 mm | WaterMark: WMK26172 | Material: Duroplast (UF) | Hose: 600 mm, 1/2-inch BSP | Weight capacity: 150 kg

 

Order with free shipping Australia-wide:  bathroomaustralia.com.au/products/bidet-seat-o-shape-left-inlet

Location:

62 Goodall Cl, Dandenong South VIC 3175 

Contact: info@bathroomaustralia.com.au

Not sure your measurements confirm compatibility? Email your measurements and 2–3 photos to the Bathroom Australia team before ordering. We'll confirm fit before you commit.