Lighting
Lumens Calculator
Lumens needed to light a room properly, based on area and the task being done.
lumens = target lux × area ÷ utilisation …
Also called how many lumens do i need · lumens for a room
Home & Construction · 7 calculators
Lighting Calculators
Lumens needed for a room, lux and foot-candles, lighting power density, bulb quantity, LED savings and efficacy.
Lighting
Lux Calculator
Illuminance in lux from lamp lumens and area, or the lumens needed for a target lux.
lux = lumens ÷ area in m²
Also called illuminance calculator · lux from lumens
Lighting
Lighting Power Density Calculator
Lighting power density in W/m² and how it compares to typical energy-code limits.
LPD = total lighting watts ÷ floor area
Also called lpd calculator · watts per square meter lighting
Lighting
Bulb Quantity Calculator
How many bulbs or fittings a room needs, and a sensible spacing grid for them.
fittings = target lux × area ÷ utilisatio…
Also called how many light fittings · downlight spacing calculator
Lighting
LED Savings Calculator
Energy and money saved by switching to LED bulbs, with the payback period.
saving = (old kWh − new kWh) × rate
Also called led vs incandescent · led payback calculator
Lighting
Luminous Efficacy Calculator
Lumens per watt of a lamp, with how it compares to other lighting technologies.
efficacy = lumens ÷ watts
Also called lumens per watt · lamp efficiency calculator
Lighting
Watts to Lumens Converter
Convert bulb wattage to lumens and back, across LED, CFL, halogen and incandescent.
lumens = watts × efficacy for that techno…
Also called lumens to watts · led equivalent wattage
Key lighting formulas
| Lumens | lumens = target lux × area ÷ utilisation factor |
|---|---|
| Lux | lux = lumens ÷ area in m² |
| Lighting Power Density | LPD = total lighting watts ÷ floor area |
| Bulb Quantity | fittings = target lux × area ÷ utilisation ÷ lumens per fitting |
| LED Savings | saving = (old kWh − new kWh) × rate |
| Luminous Efficacy | efficacy = lumens ÷ watts |
| Watts to Lumens Converter | lumens = watts × efficacy for that technology |
Lighting questions
How many lumens is a 60 W bulb?
About 800 lumens. An LED producing the same light uses around 9 W.