WC Rough-In Calculator
Position your toilet correctly before the plumber pours the floor. Pick the WC type, enter your model's S-trap spread or outlet height, and get the drain centre, side and front clearances, cistern height and a wall-fit check. Indicative India 2026 — always confirm against your WC's spec sheet.
Your WC & wall
Vertical waste into the floor.
Common set-out values
| Item | Typical | Note |
|---|---|---|
| S-trap spread (close-coupled) | 220 mm | Compact / short projection |
| S-trap spread (standard) | 300 mm | Most common Indian one-piece |
| S-trap spread (long) | 400 mm | Older / imported large pans |
| P-trap outlet height | ~180 mm | Centre of horizontal waste |
| Wall-hung waste bend | ~230 mm | Set by concealed carrier frame |
| Cold water point | ~150–200 mm | Above floor, offset from centre |
Measure the S-trap spread on your model's spec sheet — it is the distance from the wall to the centre of the waste. Standard Indian codes want ~380 mm from the WC centre to any side wall and ~600 mm of clear space in front. All figures are from the FINISHED wall and floor, so allow for tiles and screed.
Drain centre from finished wall
0 mm
for a Floor-mounted · S-trap (floor outlet) — needs a 0 mm wide bay (380 mm each side of the centre-line)
Drain centre from wall
300 mm
S-trap spread
Min bay width
760 mm
380 mm × 2
Front clearance
600 mm
depth needed 1,280 mm
Seat height
400 mm
finished floor → seat
Key set-out dimensions, all in mm from the finished wall/floor. Indicative — confirm against your WC spec sheet.
Check the WC position & plumbing
Get DesignAI to sanity-check this rough-in and the fit beside your basin and door.
Estimates are indicative and measured from the finished wall and floor. Every WC model differs — always set out the drain against your pan's own spec sheet, allow for tile and screed thickness, and have your plumber dry-fit the pan before casting or chasing the waste. Clearances follow common Indian practice and may need to increase for accessible or luxury bathrooms.
Frequently asked questions
- What does the WC rough-in calculator work out?
- It gives you the set-out dimensions a plumber needs to position a toilet before casting the floor. Pick floor S-trap, floor P-trap or wall-hung, enter your model's S-trap spread or outlet height, and it returns the drain centre from the finished wall, the side and front clearances, seat or flush-plate height, and a check on whether your wall length fits the bay.
- What inputs do I need and what are sensible defaults?
- You need your WC type and its rough-in value from the spec sheet: an S-trap spread of about 300 mm is the most common Indian one-piece, roughly 180 mm outlet height for a P-trap, and around 230 mm waste-bend height for wall-hung. For clearances, common Indian practice is about 380 mm from the WC centre-line to any side wall and roughly 600 mm of clear space in front.
- How accurate is the result and what should I verify?
- Treat the numbers as indicative for planning, not final construction figures. Every pan model differs, so always set the drain out against your own WC's spec sheet. All values are measured from the finished wall and floor, so add for tile and screed thickness, confirm clearances against NBC 2016 Part 9 and any accessibility needs, and have the plumber dry-fit the pan before chasing the waste.
Related Guides — Deep-dive reading
Bathroom Plumbing Schedule (India): Point-by-Point Rough-In Heights & Pipe Sizes
A working bathroom plumbing schedule for Indian projects — every water inlet and outlet point with its rough-in height from finished floor level, CPVC/UPVC pipe size and site notes, so your plumber roughs-in the wall correctly the first time and no fixture lands at the wrong height.
BathroomsBathroom Toilet India: The Complete Guide to WCs, Commodes & Water Closets (2026)
Indian squat vs Western commode, floor-mounted vs wall-hung with concealed cistern, the S-trap and P-trap outlet and its rough-in distance, dual-flush water norms, rimless and comfort-height trends, the health-faucet rule, and a rupee cost comparison — everything that decides which toilet is right for an Indian home.
BathroomsHow to Choose a Toilet in India: A Buyer's Guide to WCs, Traps, Flush & Budget (2026)
The make-or-break trap and rough-in check, floor-mounted vs wall-hung, one-piece vs two-piece, flush type and water use, seat and rimless upgrades, good/better/best rupee tiers, what's actually in the box, and how to spot a fake before you pay.
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