How to Choose a Toilet: What to Check Before You Buy

On this page (8 sections)

1. How do you choose a toilet that fits your bathroom?
2. Should you choose a round or elongated bowl?
3. What toilet height should you choose?
4. How should you compare toilet flush types and water use?
5. Should you choose a one-piece or two-piece toilet?
6. How do you choose between these four toilets?
7. What common toilet-buying mistakes should you avoid?
8. How to choose a toilet: which one should you buy?

To choose a toilet, match its rough-in and dimensions to your bathroom first, then select the bowl shape, height and flush features that suit the people who use it. This guide to how to choose a toilet covers fit, comfort, water use, installation and care.

A toilet can have appealing features and still be a poor fit if it crowds a door or misses the drain position. Measure the space first, then compare models against those limits.

For a shortlist by fit and use, see our best toilets by style, height and fit.

How do you choose a toilet that fits your bathroom?

Start with rough-in, floor space and clearance. Those measurements narrow your options before you compare appearance or flush features.

The rough-in is the distance from the finished wall behind the toilet to the center of the floor bolts or drain. Many toilets are made for a 12 in rough-in, but some bathrooms need a different size.

Measure from the wall to the front of the existing toilet, then note the space available on each side. Check how the door swings and whether drawers, cabinets or other fixtures will block access.

Compare these measurements with the toilet’s outside dimensions. Leave enough room to sit, stand and move around it without the bowl crowding the doorway or walkway.

If your rough-in is near a model’s stated measurement, account for baseboards and the exact installation instructions. Our rough-in measuring guide explains how to take the measurement before you shop.

How to choose a toilet by rough-in and room size

When choosing a toilet, confirm the rough-in before settling on a style. A model built for a different drain position may not install correctly without additional work.

Use the finished wall as your reference point, not the baseboard. Record the measurement and compare it with the toilet’s required rough-in, then verify the room dimensions separately.

A common mistake is measuring only the old bowl’s depth. The replacement may have a different shape, so compare its full dimensions and check door and fixture clearance too.

Should you choose a round or elongated bowl?

Choose a round bowl when front-to-back space is tight, and consider an elongated bowl when you want more front-to-back room. Your best option depends on clearance and who will use the bathroom.

Round bowls can work well in compact bathrooms or powder rooms, where the extra depth of an elongated shape could affect a door swing or walkway. Measure the available space instead of assuming that a familiar shape will fit.

Elongated bowls extend farther into the room. If you prefer this shape, check the full depth and make sure there is comfortable clearance in front of the toilet.

The Swiss Madison Sublime II has a round bowl and measures 24 in deep by 14 in wide. Its 12 in rough-in still needs to match your drain location.

Compare the trade-offs in our round vs elongated toilet guide.

How to choose a toilet bowl shape for a small bathroom

For a small bathroom, check depth and door movement before choosing the bowl shape. A round bowl may leave more usable space in front, while an elongated bowl needs enough clearance to avoid a cramped layout.

Don’t rely on “compact” in a name by itself. Compare the listed dimensions with your actual room and fixture positions.

What toilet height should you choose?

Choose a height that feels comfortable for the people who use the bathroom. Chair or universal height can make sitting and standing easier for many people, while a standard-height bowl may suit others better.

Height terms can vary, so check whether a measurement describes the bowl, seat or complete toilet. If several people share the bathroom, consider their needs rather than assuming one height works for everyone.

The TOTO Drake is described as Universal Height and taller than a standard toilet. The Casta Diva has a 17 in chair seat height, while the American Standard H2Option has a 16 ½ in chair-height bowl.

Read our guides to chair-height toilets and standard, chair and extra-tall bowl heights for more detail.

How to choose a toilet height for the people using it

A chair-height or universal-height model is a useful starting point if sitting down and standing up comfortably matters. A standard-height model may feel more natural to users who prefer a lower seat.

Don’t compare height labels without checking what they measure. One model may give bowl height and another seat height, so look at the specific measurement and descriptions before deciding.

How should you compare toilet flush types and water use?

Compare gallons per flush (GPF) and the flush controls. A lower stated volume uses less water per flush, while a dual-flush model offers different flush options.

The TOTO Drake uses 1.6 GPF. The Swiss Madison Sublime II and Casta Diva offer dual-flush options of 1.1 and 1.6 GPF, while the American Standard H2Option offers 0.92 and 1.28 GPF options.

The TOTO Drake has a left-hand lever. The other models use top-mounted controls, including dual-flush buttons on the Swiss Madison and American Standard toilets.

Consider which control position will be easiest to reach in your bathroom.

The Drake combines a siphon jet bowl with a 3 in flush valve. The Casta Diva has a siphon jet flush and fully glazed trapway.

The H2Option has a direct-fed jet and fully glazed trapway. Swiss Madison describes its trapway as fully glazed.

For a closer look at water-use labels, see what a WaterSense toilet is.

How to choose a toilet flush for everyday use

A single-flush toilet keeps the control simple, while a dual-flush toilet lets you choose between two flush volumes. Think about whether everyone using the bathroom will find the controls clear and easy to operate.

Avoid choosing by GPF alone. Compare the flush design and controls as well as the volume, then check whether the toilet meets your water-use goals and any local requirements.

Should you choose a one-piece or two-piece toilet?

A one-piece toilet combines the tank and bowl, while a two-piece model has a separate tank and bowl. Compare their form, dimensions and included parts with your installation plan.

The Swiss Madison Sublime II and Casta Diva are one-piece toilets. The TOTO Drake and American Standard H2Option are two-piece models.

A one-piece design can have fewer joins around the tank, which may make its exterior easier to wipe. The Casta Diva describes its skirted shape as having fewer hard-to-reach areas.

If easy access for repairs matters more to you, compare how each toilet is constructed and what installation instructions require.

Don’t assume the style determines the fit. Check the overall depth and width, rough-in and mounting details for the specific model.

How to choose a toilet based on installation parts

Before ordering, check which components come with the toilet. A missing seat or installation supply can delay a replacement even when the toilet itself fits.

The Drake includes the tank and bowl, but its seat, wax ring, mounting bolts and water supply lines are separate. The American Standard H2Option seat is also sold separately.

The Swiss Madison Sublime II includes a seat, wax ring, bolt kit and cover caps. The Casta Diva includes an elongated slow-close seat, wax seal and installation hardware.

Count what you already have and what the new installation will require. If you’re replacing an existing toilet, plan how to move and remove it with our guide to removing an old toilet without a mess.

How do you choose between these four toilets?

Choose based on the main need your measurements and household reveal. These models suit different priorities, so compare their shape, height, flush options and installation parts against your checklist.

Choose the TOTO Drake if you want an elongated, Universal Height two-piece toilet with a left-hand lever, CEFIONTECT glaze and TORNADO FLUSH. It uses 1.6 GPF and has a 12 in rough-in.

Skip it if you need a round bowl, a dual-flush control or a seat and installation supplies included in the purchase.

Choose the Casta Diva if a one-piece design, a 17 in chair seat and dual-flush options are priorities. It has an elongated bowl, 12 in rough-in, slow-close seat and installation hardware.

Skip it if you prefer a lower standard-height seat or want the more familiar two-piece form.

Choose the American Standard H2Option if you want a two-piece chair-height toilet with dual-flush controls and a 12 in rough-in. Its lower and fuller flush options are 0.92 and 1.28 GPF.

Skip it if having a seat included is essential, since the seat is sold separately.

Choose the Swiss Madison Sublime II if you need a round bowl for a tighter room and want a one-piece toilet with a quick-release, soft-close seat. It has a 12 in rough-in and dual-flush volumes of 1.1 and 1.6 GPF.

Skip it if you need chair height, since this model is described as standard height.

What common toilet-buying mistakes should you avoid?

Avoid ordering based on one feature or measurement alone. Check the drain position, room dimensions, height, flush controls and included parts as a set.

• Don’t measure from the baseboard when checking rough-in; use the finished wall.
• Don’t compare only the old toilet’s depth; the new model may have a different shape.
• Don’t assume “chair height” and “universal height” use identical measurements.
• Don’t assume a toilet includes a seat, wax ring, bolts or supply line.
• Don’t pick a lower GPF without considering the flush controls and design.
• Don’t forget to check the door swing and nearby fixtures against the toilet’s full dimensions.

If you are replacing an existing toilet, plan ahead for removal and the parts needed to install the replacement. The toilet removal guide covers the old fixture.

How to choose a toilet: which one should you buy?

Choose a toilet by fit first, then by comfort and flush preference. Start with the rough-in and full room measurements, then narrow the options by bowl shape and height.

Pick the Swiss Madison Sublime II for a round bowl in a tighter space, the Casta Diva for a taller one-piece design with dual flush, the H2Option for a two-piece dual-flush model, or the TOTO Drake for an elongated Universal Height toilet with a left-hand lever. Before you order, verify dimensions and confirm which installation parts you still need.

For a broader comparison by shape, height and use, start with our toilet styles and features guide.

Frequently asked questions

What should I check first when choosing a toilet?

Check the rough-in first, since it determines whether the toilet can fit the drain location. Then measure floor space and door clearance, choose a bowl shape and height for the people using it, and compare flush type, water use and installation needs.

Is an elongated or round toilet better?

An elongated bowl offers more front-to-back space, while a round bowl can suit a tighter bathroom. Measure the room and check door or cabinet clearance before choosing.

The best shape is the one that fits the room and the people who use it.

What toilet height should I choose?

Standard height works for many people, while chair or universal height can make sitting and standing easier for some users. Compare the stated bowl or seat height carefully, since brands may describe measurements differently.

Consider how the height feels for everyone sharing the bathroom.

Do all toilets use a 12 inch rough-in?

No. Many toilets use a 12 in rough-in, but other configurations exist.

Measure from the finished wall to the center of the floor bolts or drain before buying, and account for baseboards that may affect the available space.

What does GPF mean on a toilet?

GPF means gallons per flush. A dual-flush toilet offers different flush volumes for liquid and solid waste.

Compare the stated volumes with your water-use goals, then check local requirements and the toilet's installation fit.