TOTO Toilet Rough-In Guide: 10 vs. 12 vs. 14 Inches & UniFit Adapters

A toilet can have the right height, bowl shape and flushing system and still be wrong for your bathroom. Before choosing a TOTO Drake, Aquia IV or any of the WASHLET+ models, check the rough-in: the measurement that determines where the toilet connects to the floor drain.

Already have a measurement and a model in mind? Ask Bath4All to check the combination before ordering.

How to measure your toilet rough-in

For a conventional exposed-bolt toilet, measure straight from the finished wall to the center of a floor bolt that aligns with the drain flange. If the toilet has been removed, measure directly to the flange center. Use the wall surface, not the face of projecting baseboard trim.

On skirted toilets, visible side fasteners may secure the bowl to separate mounting blocks. Their position may not identify the drain center. Check the existing toilet’s installation drawing or have your plumber confirm the flange location.

Write down the actual measurement. If it is between the nominal sizes, do not round it and place an order. Send the measurement and a photo showing both ends of the tape so the proposed model’s drawing can be checked.

If the room is being remodeled, tell your installer about planned tile or other wall finishes. Confirm the measurement from the final wall surface before selecting the toilet.

10-inch vs. 12-inch vs. 14-inch: where to start

A dedicated 10-inch TOTO Drake

The Drake CST776CEFG.10#01 is an elongated, Universal Height, 1.28 GPF toilet made for a 10-inch rough-in. The .10 in this model number matters: its bowl is the C776CEFG.10. It is not a standard 12-inch Drake bundled with a UniFit adapter.

TOTO’s specification sheet calls for a nominal 10-inch flange position to maintain the intended wall gap. The seat and supply line are sold separately. Check the included components rather than assuming the toilet pictured comes with everything needed for installation.

A standard 12-inch TOTO Drake

If your confirmed rough-in is 12 inches, the Drake CST776CEFG#01 is a straightforward model to compare. It has an elongated bowl, Universal Height and a 1.28 GPF flush. Its toilet seat is sold separately.

For differences between the current families, see our TOTO Drake vs. Drake II comparison. Choose the rough-in configuration first, then compare styling and features within the options that fit.

How TOTO UniFit adapters work – and which one to buy

On supported toilets, a UniFit adapter connects the bowl’s outlet to the existing floor flange. Selecting the approved adapter length changes how the toilet sits relative to that flange. It does not relocate the drain inside your floor.

Match both the rough-in length and the adapter family. A part described as “14-inch UniFit” is not automatically suitable for every skirted TOTO toilet. For example, TOTO documents TSU48 adapters for the Aquia IV models listed in its parts manual, while other installation instructions specify a different family, such as TSU08W.

For the Aquia IV CST446CEMGN#01, TOTO lists a standard 12-inch rough-in with optional 10- and 14-inch configurations. The corresponding parts manual identifies:

• TSU48.10: 10-inch UniFit adapter.
• TSU48.12: the 12-inch version.
• TSU48.14: 14-inch UniFit adapter.

Use that mapping for the specified model, not as a shortcut for every toilet carrying the Aquia name. Check the full bowl or toilet number against its parts list before ordering an adapter. Open the product page for current availability, and confirm the adapter’s delivery timing before scheduling installation.

Before you order: check the whole installation

Ask your installer to review the specification sheet and installation instructions for the exact model. Send the links before purchasing, so any extra parts can be identified together.

• Room fit: compare the toilet’s overall projection, door swing and space around the bowl. Rough-in and overall toilet length are different measurements.
• Supply access: check the shutoff valve location against the skirt and the manufacturer’s installation drawing.
• Installation parts: confirm the required seal, bolts, supply connection and adapter. UniFit instructions may list a wax ring and mounting bolts as separately required materials.
• Seat choice: distinguish a bowl-and-tank set from a toilet with a SoftClose seat or a complete WASHLET package.
• Bidet plans: verify seat compatibility and power access separately. A rough-in adapter does not add WASHLET+ or auto-flush capability.

If you are replacing both the toilet and seat, browse TOTO toilet and WASHLET combinations, then confirm the chosen package’s rough-in and included parts. Our S2, S5 and S7 buying guide can help with the seat features.

Common rough-in questions

Can a 12-inch toilet go on a 14-inch rough-in?

It may, but a conventional 12-inch model generally leaves more space behind the tank. On an approved UniFit toilet, the correct 14-inch adapter can position the toilet closer to the wall. Check the model’s drawing for the final clearance.

Can I use a UniFit adapter on a standard Drake?

No – not on Drakes. Do not buy an adapter to convert the standard Drake models shown here. For a 10-inch installation, get one of the dedicated 10" rough-in models, such as the CST776CEFG.10#01 instead. The adapter approach requires a toilet specifically designed for that system.

Does “Universal Height” mean a universal rough-in?

No. Universal Height describes the toilet’s height category. The Drake examples above are both Universal Height, but one has a 10-inch rough-in and the other has a 12-inch rough-in.

What if I measure 11½ inches?

Have the exact measurement checked against the proposed model’s dimensional drawing. Also confirm that you measured from the finished wall to the drain center. 12" rough-in toilets usually offer some wiggle room so half an inch more or less should be okay.