Lumens calculator.
Start with your room.

Length times width, that's it. A 12 ft by 10 ft room = 120 sq ft. Measuring in inches? Multiply length by width, then divide by 144. Working in meters? Same idea , length times width gives you square meters. (㎡)

The presets range from 5 lm/sq.ft for parking areas to 50 for retail. They support early estimates. For a specification, use the recommendations for the actual task and the requirements that apply to the project.

CRI describes color rendering relative to a reference light source. Ra 80 is a common general-lighting specification; Ra 90 or higher may suit retail, hospitality, and other color-sensitive uses. Check R9 separately when reds and skin tones matter.

Warm white, around 2700–3000K, is common in bedrooms and living rooms. Around 4000K is common in workspaces. Compare samples with the room finishes and daylight before choosing a CCT for the whole project.

The first IP digit describes protection from solid particles; the second describes protection from water. Choose the rating for the actual exposure and installation location. IP ratings alone do not establish corrosion resistance or bathroom-zone suitability.

A maintenance factor below 1 allows for lumen depreciation and dirt. This tool offers 0.80, 0.70, and 0.60 scenarios. Choose a value that fits the environment and maintenance plan, then check it against the fixture data.

Divide lumens by the efficacy rating. A good LED runs about 100-130 lm/W, so 800 lumens needs roughly 6-8 watts. CFLs are around 50-70 lm/W, halogens 15-20. The converter tool up the page handles this automatically.

Illuminance decreases with the square of distance. Double the distance = 1/4 the illuminance. The distance calculator above factors beam angle into the illuminance result.

Compare delivered lumens per watt for the complete lamp or fixture. LEDs usually use less power than incandescent or halogen lamps at similar light output. Payback depends on purchase cost, operating hours, and your electricity rate.

Total lumens divided by per-fixture lumens. But here's the catch , you need to account for maintenance factor. Say your room needs 2,400 lumens and each fixture puts out 800. On paper that's 3 fixtures. But with MF 0.8, you actually need 3,000 lumens, so 4 fixtures. The calculator above does this automatically.

R9 measures the rendering of a saturated red sample and is not included in the average Ra score. Request R9 data when comparing lamps for food, fabrics, artwork, or skin tones.

IK describes resistance to mechanical impact. Choose it for likely knocks or vandalism. Coastal installations also need suitable housing materials, coatings, and corrosion test evidence; a higher IK rating does not address salt exposure.

Use narrow beams for focused accents and wider beams for broader coverage. Compare mounting distance and aiming with the target surface; the beam calculator provides a geometric starting estimate.

The room calculator estimates total lumens and fixture count from area, target light level, fixture output, and maintenance factor. Ceiling height triggers an advisory; it does not change the count.

Select Warehouse for an initial estimate, then check aisles, loading areas, racks, and workstations separately. The room calculator does not model vertical light on shelving or obstructions. Use a photometric layout to choose high-bay positions.

Lumens measure light output; lux and foot-candles measure light arriving at a surface. This tool uses an area-based estimate to connect the two. Surface reflectance, mounting height, and fixture distribution require a separate lighting model.