How does the bathroom lighting calculator work?

It uses a lux-based general lighting method. It converts your room size to square metres, multiplies by your target lux (about 175 for everyday, 300 for grooming, 500 for full task light) and divides by a utilisation and maintenance factor to get the lumens needed. That figure is divided by the lumens per fixture and rounded up to give a downlight count, plus a separate mirror task layer.

What inputs do I need to enter?

Enter the room length and width in feet, pick a target ambience, choose your ambient fixture or type in custom lumens, set a maintenance factor for how clean or humid the space stays, and give the mirror width. Sensible Indian defaults are a 5 by 7 ft room at grooming brightness with roughly 900 lumen LED downlights and an average maintenance factor of 0.7.

Where do I need waterproof IP-rated lights in a bathroom?

Use fittings rated at least IP44 in splash zones around the shower, bath and basin, and IP65 for anything directly overhead in the shower where it meets spray. Dry areas away from water can use ordinary fittings. IP ratings and wet-zone rules vary, so confirm the exact rating, circuit load and dimmer sizing with a licensed electrician per NBC 2016 Part 8 before you buy.

Lighting Calculator

Bathroom Lighting Calculator

Enter your room size and how bright you want it. Get the lumens needed, the number of downlights and a mirror task-light suggestion, plus indicative wattage and IP guidance for wet zones. Indicative India 2026 — always confirm with your electrician.

Your bathroom & light level

Room length (ft)

Room width (ft)

Target ambience

Ambient fixture

Maintenance factor

Mirror width (ft)

Layered plan (add accent for niches / cove / shower)

Lumens needed = area (m²) × target lux ÷ (utilisation 0.6 × maintenance 0.7). We round fixtures up, so delivered light usually sits a little above target. Use IP44+ fittings in the wet zone around the shower/bath and IP65 directly overhead. Confirm circuit loads with your electrician.

Ambient downlights to fit

0 downlights

delivering 0 lm (~349 lux vs 300 lux target) at 900 lm each

Lumens needed

2,323 lm

for 3.3 m²

Total (all layers)

4,400 lm

ambient + task + accent

Mirror task light

1,700 lm

2 × 850 lm side lights

Indicative power

46 W

@ 95 lm/W LED

Lumens by layer (ambient and mirror task). Indicative — confirm with your electrician.

Plan the fixtures & colour temperature

Get a layout, warmth and IP-rating plan for this bathroom from DesignAI.

Go deeper

Bathroom mirror size calculator Bathroom cost calculator Electricity consumption calculator

Estimates are indicative and round fixtures up to whole units. Lux targets, fixture lumens and efficacy vary by product — confirm exact lumen output, colour temperature and wet-zone IP ratings (IP44 minimum in splash zones, IP65 over the shower) with your electrician, and size the circuit and dimmer to the real connected load before ordering.

Frequently asked questions

How does the bathroom lighting calculator work?: It uses a lux-based general lighting method. It converts your room size to square metres, multiplies by your target lux (about 175 for everyday, 300 for grooming, 500 for full task light) and divides by a utilisation and maintenance factor to get the lumens needed. That figure is divided by the lumens per fixture and rounded up to give a downlight count, plus a separate mirror task layer.
What inputs do I need to enter?: Enter the room length and width in feet, pick a target ambience, choose your ambient fixture or type in custom lumens, set a maintenance factor for how clean or humid the space stays, and give the mirror width. Sensible Indian defaults are a 5 by 7 ft room at grooming brightness with roughly 900 lumen LED downlights and an average maintenance factor of 0.7.
Where do I need waterproof IP-rated lights in a bathroom?: Use fittings rated at least IP44 in splash zones around the shower, bath and basin, and IP65 for anything directly overhead in the shower where it meets spray. Dry areas away from water can use ordinary fittings. IP ratings and wet-zone rules vary, so confirm the exact rating, circuit load and dimmer sizing with a licensed electrician per NBC 2016 Part 8 before you buy.

Related Guides — Deep-dive reading

Common Home Lighting Mistakes in India (and How to Fix Them) (2026)

The most common lighting mistakes in Indian homes — one bright tubelight per room, everything blue-white, glare, no dimming, dark stairs — and the specific, affordable fix for each, plus the one habit that causes half of them: not planning the scheme before the electrician wires.

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Bathroom Lighting Design: Mirror, Ambient & IP Zones (2026)

How to light an Indian bathroom so the mirror is shadow-free and the wet zones are safe — the vanity task light that makes or breaks grooming, the ambient and accent layers, colour temperature and CRI for true skin tones, and the IP-rating wet-zone rules a licensed electrician must wire.

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Bathroom Lighting India: The Complete Guide to Layers, Lux, Colour Temperature & IP Safety Zones (2026)

How to light an Indian bathroom properly — the three layers of ambient, task and accent light, the right lux levels and a neutral ~4000K colour temperature for grooming, the IP safety zones near water that decide which fitting goes where, waterproof fixtures, dimming and scenes, mirror lighting done right, motion sensors and energy.

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