Check your bathroom layout
Room dimensions and the fixtures you want in it.
How this planner works
- Every fixture carries a floor-area allowance that includes its own footprint plus the clear space in front of it. A WC is 7 sq ft: a 27-inch-deep pan in a 30-inch-wide zone with 24 inches of clear front.
- Base circulation is 6 sq ft, the space needed to enter, turn and dry yourself, over and above the fixture clearances.
- Required = 6 + WC + basin + wet zone + washing machine + door swing. That total is compared against your room area.
- Minimum width is checked separately, because area alone can pass while the room is still too narrow: 3.5 ft with no wet zone, 4 ft with a shower, 5.5 ft with a bathtub.
- The recommended arrangement is chosen by proportion. A length-to-width ratio of 1.5 or more returns a linear plan; anything squarer returns an L plan.
- Waterproofing area = floor + perimeter × 4 ft of coping, reported so you can price it against the waterproofing calculator.
| Fixture | Area allowance | What that covers |
|---|---|---|
| Base circulation | 6.0 sq ft | Entering, turning, drying |
| WC | 7.0 sq ft | Pan plus 24 in clear front, 30 in wide zone |
| Wall-hung basin | 4.5 sq ft | Basin plus 21 in of standing space |
| Vanity, 24 in | 6.0 sq ft | Counter, storage below, standing space |
| Corner shower 900 × 900 | 10.0 sq ft | Tray plus entry and door swing |
| Enclosure 1200 × 900 | 13.0 sq ft | Larger tray plus entry |
| Bathtub | 20.0 sq ft | 1700 × 750 mm tub plus getting-in space |
| Washing machine | 6.0 sq ft | Front loader plus door swing |
| Inward-opening door | 6.0 sq ft | The quarter circle the leaf sweeps |
Design and build under one accountable roof
Worked example — a standard Mumbai bathroom
| Line | Allowance | Running total |
|---|---|---|
| Base circulation | 6.0 | 6.0 |
| WC | 7.0 | 13.0 |
| Wall-hung basin | 4.5 | 17.5 |
| Corner shower | 10.0 | 27.5 |
| Door opens outward | 0 | 27.5 |
| Room available | 7 × 4.5 ft | 31.5 sq ft |
| Balance | 31.5 − 27.5 | +4.0 sq ft |
| Width check | 4.5 ft against 4.0 ft minimum | Passes |
At a length-to-width ratio of 1.56 the tool returns a linear plan — basin nearest the door, WC in the middle, wet zone at the far end behind a glass partition.
The three things that decide a Mumbai bathroom
The soil stack comes first. In an apartment the WC has to sit within about two feet of the existing stack, because moving it further needs a floor-level offset and a fall, and that means raising the whole bathroom floor by three to four inches. That is legitimate work, but it changes the door, the threshold and the level relationship with the bedroom outside, and it is not a detail to discover after demolition.
The second is the wet and dry split. A glass partition costs ₹9,000–18,000 and it is the single best thing you can do to a small Indian bathroom. It keeps the WC seat and the floor outside it dry, it stops the vanity shutters swelling, and it means the room can be used by one person while another has just showered. Ten square feet of the area budget goes to the wet zone precisely so this is possible.
The third is ventilation. A bathroom with no window needs a mechanical exhaust rated at least 6 air changes per hour, ducted to the shaft rather than into the false ceiling. Mumbai humidity plus an unventilated bathroom equals mould on the ceiling within eighteen months, and repainting it every year is not a fix.
Every constant on this page comes from Greenbox site records — measured drawings, signed BOQs and completion certificates from projects delivered between 2023 and 2026 — rounded to the figures an estimator would actually write down. We publish them so the arithmetic can be audited rather than trusted. Treat the output as a planning figure: accurate enough to brief a landlord, a bank or a family, and not accurate enough to sign a contract against.
What this tool does not cover
- Plumbing feasibility. This tool checks area and width, not whether your building's stack allows the arrangement.
- Ceiling height and the drop needed for concealed cisterns, shower mixers and exhaust ducting.
- Grab rails, wheelchair turning circles and other accessibility requirements, which need a 5 ft clear turning space.
- Counter-top basins and vessel sinks, which sit higher and need their own tap and splash allowance.
- Cost, which the bathroom renovation cost calculator handles.
- Waterproofing quantities — see the waterproofing area calculator.
Selected work by Greenbox Design Studio. Tap any image to enlarge.
Frequently asked questions
What is the minimum bathroom size in India?+
About 27.5 sq ft for a WC, basin and corner shower with usable circulation — so roughly 7 × 4 ft. A WC and basin alone fit in 18 sq ft. Below 4 ft of width a shower stops being comfortable however long the room is.
Can I fit a shower in a 4 ft wide bathroom?+
Yes, a 900 × 900 mm corner shower fits a 4 ft width with the tray against one wall. A 1200 × 900 enclosure needs 4.5 ft, and a bathtub needs 5.5 ft because you have to be able to stand alongside it.
Should a bathroom door open inward or outward?+
Outward, or slide, wherever the layout allows. An inward-opening door sterilises about 6 sq ft of a small bathroom — frequently the exact space you needed for the shower. The one caution is that an outward door must not swing into a corridor where someone could walk into it.
How much does a glass shower partition cost?+
₹9,000 to ₹18,000 for a fixed 8 mm toughened panel with a channel and a support bar, and ₹22,000 to ₹45,000 for a hinged or sliding enclosure. It is the highest-return item in a small bathroom because it keeps the rest of the room dry.
Where does the WC have to go?+
Within about two feet of the existing soil stack. Moving it further needs a floor-level offset with a fall, which raises the finished bathroom floor by three to four inches and changes the door and the threshold. Plan the rest of the layout around the stack.