Will a Bidet Seat Fit My Toilet? An Australian Sizing Guide
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This is the question we get asked more than any other, and it is also the reason behind most returns in this category. The good news is that it takes about three minutes to answer properly, and once you have the numbers you will never have to guess again.
A bidet seat replaces your existing toilet seat. It bolts to the same two holes, connects to the same water line that feeds your cistern, and on electric models plugs into a nearby power point. So fit comes down to five things, and this guide walks through all five in order.
The five things that decide whether a seat fits
- The shape of your toilet pan
- The length available from the cistern to the front of the bowl
- The spacing of your seat bolt holes
- Which side your water supply comes in on
- Whether there is a power point within reach, for electric models
The diagram at the top of this page marks four of these. A is the flat area behind the seat bolt holes, between the holes and the cistern. B is the distance between the two bolt holes. C is the distance from the bolt holes to the front edge of the bowl. D is the full length from the cistern to the front edge, and it is the one that decides it most often. If you only measure one thing, measure D. The exact figures vary from one seat to another, so check the product page for the model you are looking at, or send us your measurements and we will confirm it for you.
Most guides stop at the first one. Numbers three and four are the ones that actually cause problems on the day, so do not skip them.
Step 1: Identify your pan shape
Stand back and look at the outline of the bowl from above. In Australia you will have one of three shapes.
D-shape. Straight or gently tapering sides with a squared-off look near the cistern and a rounded front. This is the shape you see in most bathrooms built or renovated in the last fifteen years or so. If your toilet looks modern and boxy, this is almost certainly what you have.
Round. A short, near-circular bowl. Common in older homes and in small second bathrooms where space was tight.
Elongated. A longer oval, noticeably deeper front to back than a round pan. Less common in Australian homes than in the United States, but you will still find them.
There is a fourth shape worth naming because it is the one that catches people out. Square-front pans, where the front edge is genuinely flat rather than rounded, generally will not take a standard bidet seat. The seat will bolt on, but it will overhang or underhang the front edge and look wrong. If your pan has a flat front, send us a photo before you order.
Step 2: Measure the length you have to work with
This is dimension D on the diagram, and it is the measurement that rules a seat in or out more than any other. Take a tape measure and measure from the base of your cistern to the front edge of the bowl, along the top.
The figure varies by model, from 490mm to 510mm. Every product page lists the exact number for that seat, alongside the other three measurements it needs. Below 490mm nothing in our range will fit, because the seat body sits at the back where a plain seat has nothing and it will foul against the cistern.
This measurement matters most on compact and older pans, and on close-coupled toilets where the cistern sits directly on the back of the pan. If you are close to the minimum for the seat you want, measure twice and tell us the number before you order.
Step 3: Check your bolt hole spacing
Lift your current seat and look at the two holes it bolts through. Measure centre to centre between them.
The Australian standard spacing is around 155mm, and the overwhelming majority of pans sold here follow it. Bidet seats are made to that spacing, with a bracket that allows some adjustment forward and back.
If your spacing is noticeably different, which happens on some imported and some very old pans, that is worth knowing before you order rather than after.
Step 4: Check which side your water comes in on
This is the step almost nobody tells you about, and it is the one most likely to turn a twenty minute job into an annoying afternoon.
Stand facing the toilet. Look at where the water supply hose connects to your cistern. Is it on your left or your right?
A bidet seat has to tee into that supply, and each model is built with its inlet on one particular side. Get it right and the connection is clean with nothing extra to buy. Get it wrong and the hose has to loop around the pan, which is ugly and sometimes not possible at all.
| Model | Water inlet, as you face the toilet |
|---|---|
| Luelue LB5000 D-Shape | Left or right, you choose when you order |
| Luelue LB5000 Round | Right |
| Every electric and hybrid model | Left |
If your connection is on the right and you want an electric seat, tell us before you order and we will talk you through it.
Step 5: Check for a power point, if you want an electric seat
Every electric bidet seat needs a standard 240V Australian outlet, and the power cord is 1.5 metres long. Measure from the back of the toilet to the nearest outlet.
Plenty of Australian bathrooms, particularly in older homes, have no outlet anywhere near the toilet. That is not the end of the conversation. It just changes which seats are on your list, and we cover the options in electric versus non-electric bidets. If you are renting, there is a bit more to think about, and we have set it out in our guide to putting a bidet in a rental.
Which Bidetto seat fits which pan shape
Here is the whole range against the three shapes, so you can find your answer in one place.
| Seat | Price | D-shape | Round | Elongated |
|---|---|---|---|---|
| Luelue LB5000 D-Shape | $219 | Yes | No | No |
| Luelue LB5000 Round | $219 | No | Yes | No |
| DIB C410 | $499 | Yes | Yes | Yes |
| Luelue LB6000 Hybrid | $549 | Yes | No | No |
| DIB C430 | $699 | Yes | Yes | Yes |
| Mr Bumwash MB1000 D-Shape | $749 | Yes | No | No |
| Mr Bumwash MB1000 Round | $749 | No | Yes | No |
| DIB C450R | $799 | Yes | Yes | Yes |
| Luelue LB7000 | $999 | Yes | Yes | Yes |
| DIB C830 | $1,099 | Yes | Yes | Yes |
| DIB C850R | $1,099 | Yes | Yes | Yes |
| DIB N850 | $1,399 | Yes | Yes | Yes |
| DIB U850 | $1,399 | Yes | No | No |
| DIB N850R | $1,499 | Yes | Yes | Yes |
| DIB U850R | $1,499 | Yes | No | No |
Two things are worth pulling out of that table.
If you have a D-shape pan, which is the most common shape in bathrooms built or renovated in the last fifteen years or so, thirteen of the fifteen seats fit you. Your choice is effectively wide open, starting at $219 with the LB5000 D-Shape and at $499 for the entry level electric C410. The U850 and U850R are the only two that are purpose-built for D-shape rather than universal, which is why they sit flatter on the pan.
If you have a round pan, common in older homes, ten of the fifteen fit. If you have an elongated pan, eight fit, all of them electric, starting with the $499 C410.
You can also compare all 15 seats side by side on specification.
Toilet types, and the ones that need a second look
Close-coupled. The standard Australian toilet, cistern sitting directly on the pan. Fits, as long as you have the length that model needs.
Back-to-wall. Pan pushed flush to the wall with the cistern concealed or semi-concealed. Usually fine. Check that the seat bolts are accessible from above, because on some models they are.
Wall-hung with an in-wall cistern. Generally the easiest of all, because there is no cistern above the pan competing for length. The thing to confirm is where the water supply is accessible, since it is often behind the wall panel.
Skirted or fully shrouded pans. Where the sides sweep down to the floor with no visible bolts underneath. These usually use a top-fixing seat bracket. Send us a photo.
One-piece smart toilets. If the seat is moulded into the toilet as a single unit, it cannot be replaced with a separate seat.
The two minute version
If you only do one thing, do this. Take a photo of your toilet from the side and a photo from directly above, and measure the distance from the cistern to the front of the bowl. Email those three things to info@bidetto.com.au and we will tell you which seats fit, including whether the cheaper ones do.
You will get an answer from a person, not a chatbot, and we would much rather spend five minutes on this than process a return.
Common questions
Do bidet seats fit all toilets?
Most, not all. Standard close-coupled, back-to-wall and wall-hung pans in D-shape, round or elongated will take a bidet seat. Square-front pans, one-piece toilets with a moulded seat, and pans with non-standard bolt spacing are the exceptions.
How do I know if my toilet is D-shape or round?
Look at the bowl from above. A D-shape has straighter sides and a squarer look where it meets the cistern. A round pan is short and close to circular. If the bowl is noticeably longer front to back than it is wide, it is elongated.
What is the minimum space needed for a bidet seat?
Between 490mm and 510mm from the base of the cistern to the front edge of the bowl, depending on the model. Each product page lists the figure for that seat. The seat body sits at the back, which is where a plain toilet seat needs no room at all.
What is the standard toilet seat bolt spacing in Australia?
Around 155mm centre to centre, and bidet seat brackets are made to suit it with some adjustment available.
Does it matter which side my water pipe is on?
Yes, and it is the most commonly missed check. Every electric and hybrid model we sell has its inlet on the left as you face the toilet. The LB5000 D-Shape lets you choose your side when you order.
Can I put a bidet seat on a wall-hung toilet?
Usually yes, and length is rarely the problem on a wall-hung pan. Confirm you can reach the water supply, since it is often behind a concealed panel.
What if I measure wrong?
Send us the photos first and we will confirm before you spend anything. That is the whole point of this page.
Before you order
Every seat we sell is WaterMark certified and everything required for installation is in the box. Nothing needs to be sourced separately.
Once you know your shape, your length and your inlet side, the range narrows down fast. Our Fit Guide has the same checks in a shorter form you can work through with a tape measure in your hand, and the buying guide covers the next question, which is which features are actually worth paying for.