Window Tool

Window-to-Wall Ratio Calculator

Enter your external wall area and glazing area to get the WWR, a verdict and the Eco-Niwas Samhita glass-VLT ceiling for that ratio — plus climate-specific advice. Indicative India 2026 guidance; confirm RETV with an envelope check.

Your facade

Units

External wall input

External wall area (m²)

Total window / glazing area (m²)

Climate zone

WWR is glazing area ÷ external (envelope) wall area for the same facade. The Eco-Niwas Samhita caps the allowed glass VLT as WWR rises and requires RETV ≤ 15 W/m². Figures are indicative — a full envelope calculation governs compliance.

Window-to-wall ratio

0.0%

Verdict: Balanced · Composite climate

0%Low ·25Balanced ·40High100%

ENS glass VLT ceiling

20%

min VLT for this WWR

RETV limit

≤ 15 W/m²

envelope must stay under

Glazing area

14.0 m²

Opaque wall

26.0 m²

ENS VLT ladder (min VLT by WWR band)

Your WWR band Other bands

Composite climate · target SHGC ≤ 0.27

Balance summer heat against winter gain. Moderate WWR with adjustable shading and low-E DGU works best across both seasons.

Design a facade that meets the code

DesignAI balances glazing, shading and glass spec to your climate, WWR target and RETV limit.

Use in DesignAI

Go deeper

WWR explained Green window standards Energy-efficient windows All window guides

Related Guides — Deep-dive reading

Window-to-Wall Ratio Explained (India): Balancing Light, View and Heat

How WWR trades daylight and view against heat, why the Eco-Niwas Samhita ties your glass spec to it, and the 20 to 40 per cent sweet spot for Indian rooms.

Windows & Glazing

Floor-to-Ceiling Windows (India): Maximum Light, and the Heat Trade-Off

Full-height glazing for Indian homes — how to win the daylight and view without losing the energy code, comfort or safety.

Windows & Glazing

Green Building Window Standards in India

The mandatory envelope code (ENS 2018 and ECBC 2017) your windows must legally meet — RETV, the WWR-VLT ladder, U-value and the compliance paperwork — and how it differs from the optional green-rating scorecard.

Windows & Glazing

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