Window Size Standards for Indian Homes (2026): Dimensions, Sills and the 10 Percent Rule — Standard window dimensions by room, sill and head heights, the NBC 10 per cent rule, and how to build a window schedule on your drawings.

Sunlit Indian bedroom with a four-by-four foot casement window set at a low sill, pale walls bouncing daylight

A window that is too small leaves a room gloomy and stuffy; one that is too large bakes it. The size and height of every opening is a design decision with a code floor under it. This guide is the reference for how big windows should be, where the sill should sit, and how to write a window schedule for an Indian home. Numbers here are indicative; always confirm against your municipal bye-laws and a fabricator's measured quote.

This is the sizing companion to the planning pillar, Window Placement Guide for Indian Homes. For the energy and glass-fraction lens see Window-to-Wall Ratio for Indian Homes, and for choosing the operation type see Types of Home Windows in India.

The 10 per cent rule: the floor under every window

The single most useful number in Indian fenestration comes from the National Building Code (NBC 2016) rule of thumb: for a habitable room the openable window area should be at least 10 per cent of the room's carpet area for light and ventilation. Some local bye-laws phrase it differently and ask for a window area of roughly one-seventh to one-eighth of the floor area for light plus ventilation combined.

Treat 10 per cent of carpet area as a minimum, not a target. A bright, well-aired room usually wants 12 to 20 per cent.

A worked example: a 12 ft x 12 ft (about 13.4 sqm) bedroom needs an openable area of at least 1.34 sqm, roughly 14.4 sqft. A single 4 ft x 4 ft window is 16 sqft of opening, comfortably clearing the floor for a casement (whole sash opens) but tight for a sliding window, where only about half the area actually ventilates. That distinction between glazed area and openable area is exactly why operation type matters as much as size.

Plan of a 12-by-12 foot bedroom showing the carpet area shaded and a four-by-four foot window, with the 10 per cent openable-area calculation called out

Standard window sizes by room

These are the sizes Indian fabricators stock and quote against. They are starting points; scale up for larger rooms, brighter light or a better view, and always size against the 10 per cent rule first.

Table figure of standard Indian window sizes by room with bedroom, living, kitchen and bathroom openings drawn to relative scale

Room	Standard size (W x H)	Notes
Bedroom	4 ft x 4 ft	Balances light, privacy and wall space for furniture
Living room	5 ft x 4 ft to 6 ft x 4 ft	Larger for view and daylight; pair with shading on west and south
Kitchen	4 ft x 3 ft	Sits above the counter and backsplash; pair with an exhaust
Bathroom	2 ft x 1.5 ft	Small for privacy; an awning or louvre sheds monsoon rain

Living rooms can go wider still (floor-to-ceiling or a bay), but past a certain glass fraction the Eco-Niwas Samhita (ENS 2018) energy code starts demanding lower-SHGC, higher-spec glazing. That trade-off is the subject of the Window-to-Wall Ratio guide and is summarised below.

Sill heights: where the bottom of the window sits

The sill is the height of the window's bottom edge above the finished floor. It is the quietest decision in a window schedule and the one residents feel every day, because it sets what you see, what furniture fits below and how private the room is.

Room	Sill height	Why
Living / bedroom	600 to 750 mm (2 to 2.5 ft)	Low enough for a seated view, high enough to place a bed or sofa below
Kitchen	1050 to 1200 mm (above counter)	Clears the worktop and backsplash; window starts where the counter ends
Bathroom	about 1500 mm (5 ft)	High for privacy while still admitting light and air

Section diagram comparing sill heights for living, bedroom, kitchen and bathroom windows against a person and a kitchen counter

Two design moves follow directly from sill height. Lower sills (around 600 mm) give a seated person, including a wheelchair user or an older resident, a view out and let in more low daylight; higher sills free up the wall below for furniture, storage or a counter, and add privacy. A senior-friendly bedroom favours the lower figure with a safe, easy-to-reach handle, a point developed in the accessibility guides below.

Head height, ceiling and how size shapes light

The top of the window, the head height, is what governs how deep daylight reaches. NBC sets a minimum clear ceiling height of 2750 mm for habitable rooms, and the higher you carry the window head within that, the deeper the light penetrates.

A side window lights a room to roughly 2 to 2.5 times the window head height. Beyond that, the back of the room goes dim.

So a window with its head at 2.1 m lights usefully to about 4.5 to 5 m into the room. A deeper room needs help: a clerestory high on the wall, a skylight, a light shelf to bounce light onto the ceiling, or windows on a second wall (dual-aspect). Crucially, tall windows light deeper than wide ones of the same area, because the daylight depth follows head height, not width. The daylight-factor mathematics behind this live in the science guides, which this guide deliberately does not repeat:

For the technique and the Daylight Factor metric, see Daylight Factor in India.
For light quality, gloom and glare by orientation, see Natural Light Planning for Indian Homes. This guide gives you the dimensions; those give you the physics.

Size meets WWR and the energy code

Window area is one input to the window-to-wall ratio (WWR), the glazed area divided by the external wall area of a room. As WWR rises the room gets more light and view but more heat, and the ENS code responds by demanding a higher minimum visible-light transmittance (VLT) and tighter heat control, with the wall envelope's RETV held at or below 15 W per sqm.

WWR band	Minimum VLT (ENS)
0 to 0.30	0.27
0.31 to 0.40	0.20
0.41 to 0.50	0.16
0.51 to 0.60	0.13
0.61 to 0.70	0.11

For most Indian rooms a WWR of about 20 to 40 per cent, with good low-SHGC glass and external shading, is the sweet spot. The full ratio logic is the job of the Window-to-Wall Ratio guide; here, just remember that picking a window size also picks a glazing spec.

How to build a window schedule (W1, W2...)

Architects do not scatter sizes across a drawing; they tag every window type with a code and list it in a schedule. This keeps the drawing readable, lets the fabricator quote in bulk and guarantees the 10 per cent rule is met room by room.

A window schedule table figure with tags W1 to W4 listing size, sill, type and quantity, alongside a partial floor plan with the tags placed

Tag	Size (W x H)	Sill	Type	Where	Qty
W1	5 ft x 4 ft	750 mm	Sliding	Living room	1
W2	4 ft x 4 ft	750 mm	Casement	Bedrooms	3
W3	4 ft x 3 ft	1100 mm	Casement	Kitchen	1
W4	2 ft x 1.5 ft	1500 mm	Awning	Bathrooms	2

How to do it:

Group identical windows under one tag. Three identical bedroom windows are all W2, not W2, W3, W4.
List width x height, sill, operation type, glazing and quantity for each tag, with a small elevation if the design is unusual.
Check each room against the 10 per cent openable-area rule as you assign tags, remembering sliding windows open only about half their area.
Cross-reference the tags on the floor plan and elevations so site staff and the fabricator read the same thing.
Add a remarks column for safety glass (toughened or laminated for low or large panes), mesh, grilles and restrictors.

Orientation, vastu and people: a quick reconcile

Size and sill interact with which wall the window is on. North and east windows can be generous because they bring cool, even, low-heat light; west and south openings should be more restrained or well shaded. This happens to agree with vastu, which favours larger windows to the north, east and northeast and smaller ones to the west and south, avoiding the southwest. Treat that as guidance harmonised with the sun, and see Vastu for Modern Homes for the framework, which this guide does not duplicate.

For older residents and wheelchair users, drop the sill to around 450 to 600 mm with safe glazing, keep handles within 800 to 1000 mm and choose lever or motorised operation, in line with the RPwD Act 2016 and CPWD Harmonised Guidelines. The whole-home view is in Accessible Home Design in India.

References

BIS Guide for Using NBC 2016: https://www.bis.gov.in/wp-content/uploads/2022/08/Booklet-Guide-for-Using-NBC-2016.pdf
Eco-Niwas Samhita 2018 (BEE/ECBC): https://ecbc.in/econiwas.html
IS 3362, natural ventilation of residential buildings: https://law.resource.org/pub/in/bis/S03/is.3362.1977.pdf
Standard door and window sizes in India (HouseYog): https://www.houseyog.com/blog/standard-door-window-sizes-india-schedule/
Standard window size by room (CiviConcepts): https://civiconcepts.com/blog/standard-window-size
CPWD Harmonised Guidelines (barrier-free): https://www.cpwd.gov.in/Publication/Harmonisedguidelinesdreleasedon23rdMarch2016.pdf