Electricity calculator group

Lighting Calculators

Work with lumens, illuminance, beam geometry, LED power, controls, and lighting energy.

Match photometric quantity to geometry

Lumens describe flux, candela describes intensity, and lux or foot-candles describe illuminance at a surface. Choose the page that matches both the known data and desired quantity.

Fixture photometry, mounting height, beam angle, reflectance, task plane, maintenance condition, and meter location should accompany a lighting result.

Lighting calculators by result

Daylight FactorCalculate daylight factor from indoor illuminance and outdoor illuminance.LED Strip Power SupplyCalculate minimum supply rating from LED strip load and capacity factor.LED Driver CurrentCalculate LED drive current from driver output power and string voltage.Lumens WattsCalculate lamp power from required lumens and luminous efficacy.Lux LumensCalculate average illuminance from lumens reaching surface and surface area.Foot-Candles LuxConvert illuminance from foot-candles to lux.Candela LumensCalculate luminous intensity from lumens in beam and beam solid angle.Light Beam DiameterCalculate ideal beam diameter from throw distance and full beam angle.Inverse Square LightingEstimate on-axis illuminance from luminous intensity and distance.LED Strip PowerCalculate strip power from strip length and power per meter.LED Strip Voltage LossCalculate voltage loss from strip current and feed resistance.LED Array ConfigurationCalculate total LEDs from LEDs in series and parallel strings.Dimmer LoadCalculate dimmer loading from connected lamp power and dimmer rating.Lighting Circuit CurrentCalculate circuit current from lighting power and supply voltage.Light Fixture SpacingCalculate fixture spacing from mounting height above task plane and spacing-to-height ratio.Illumination UniformityCalculate uniformity ratio from minimum illuminance and average illuminance.Lighting Wall-Plug EfficiencyCalculate wall-plug efficiency from visible optical power and electrical input power.Occupancy Sensor SavingsCalculate annual energy saved from controlled lighting power and avoided operating hours.Lighting Energy CostCalculate annual lighting cost from annual lighting energy and electricity price.Lumen DepreciationCalculate maintained lumens from initial lumens and lumen maintenance.

Beam and illuminance calculations

Inverse-square illuminance uses actual distance, not a pre-squared entry. Beam diameter uses throw distance and full beam angle, with the half-angle handled inside the formula.

Real fixtures are not point sources and beam edges are not perfectly sharp. Use manufacturer photometric files for layout decisions that require spatial accuracy.

LED power and circuit loading

LED driver current, strip power, supply margin, voltage loss, dimmer loading, and circuit current are separate checks. Confirm driver compatibility and thermal derating.

Series and parallel LED counts must be whole numbers. Voltage and current regulation headroom should be reviewed before selecting a configuration.

Energy, controls, and maintained light

Occupancy savings depend on genuinely avoided hours, while lighting cost also requires the applicable tariff. Control behavior and user patterns can dominate the result.

Lumen depreciation and uniformity should be evaluated on the maintained task plane, not only from initial lamp or fixture output.