Lumen Footcandle Chart

Use this worksheet after the calculator result to document room area, task plane, total lumens, fixture count, average illuminance, foot-candles, lux, CU, LLF, and photometric follow-up.

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Quick reference table

A lumen footcandle chart is a calculator-led planning worksheet for average illuminance. It keeps lumens, area, task plane, fixture count, CU, LLF, foot-candles, and lux together before the electrician compares the result with fixture spacing, lighting level targets, or a photometric layout.

Lumen to foot-candle worksheet

Lumen to foot-candle worksheet
Result item	Record from calculator	Field check before layout
Room or zone area	Square feet or square meters	Confirm the actual lit area and task plane height
Total lumens	Lamp, fixture, or room total	Check fixture count and delivered output per fixture
Average illuminance	Foot-candles and lux	Compare with the intended task or room target
Adjustment factors	CU, LLF, or none	Do not mix adjusted and unadjusted lumen results
Fixture count	Planned number of fixtures	Route to spacing, circuit load, and product review

Illuminance result handoff

Illuminance result handoff
If the result is used for	Keep this field visible	Next chart or review
Fixture count	Lumens per fixture and average fc	LED power lumen chart
Room target comparison	Task plane and planning target	Lighting level reference chart
Metric product data	Lux equivalent and area basis	Manufacturer photometric data
Circuit planning	Fixture count and input watts	Lighting circuit calculator
Final layout	Mounting height, spacing, reflectance	Photometric layout or field check

Formula basis

Foot-candles = lumens / square feet. Lux = lumens / square meters. 1 foot-candle = 10.764 lux.

Lumens are total luminous flux from the selected lamp, fixture, or fixture group.
Square feet or square meters are the room, zone, or task-plane area used in the calculator.
Foot-candles are lumens per square foot for U.S. planning work.
CU and LLF are optional utilization and light-loss factors when the calculator result included them.

Worked examples

Open office average illuminance screenRecord a 1,200 ft2 area, 36,000 planned lumens, 30 fc average, 323 lux equivalent, fixture count, and whether CU and LLF were included before comparing fixture layouts.

Warehouse aisle task-plane noteFor a storage aisle, keep the aisle area, rack shadowing note, target task plane, lumens per high-bay, and calculated average foot-candles together before photometric review.

Assumptions. Balanced load and line-to-line voltage assumptions behind this chart.

The worksheet uses average illuminance and does not prove uniformity, glare control, emergency-lighting coverage, or final fixture layout.
Fixture photometrics, room reflectance, mounting height, controls, maintenance, and owner criteria can change the final design result.
CU and LLF should be documented when used; a raw lumen-per-area estimate should not be compared with an adjusted result without labeling the difference.

Code and standard notes. Planning limits that should be checked before final equipment selection.

Use this chart as a calculation record; verify owner criteria, adopted energy or workplace requirements, fixture photometrics, manufacturer data, and AHJ expectations before final design decisions.

How to use this chart

1Start from the resultBring over area, total lumens, target foot-candles or lux, task plane, fixture count, and any CU or LLF factors already used.

2Keep units pairedDo not compare a foot-candle result from square feet with a lux result from square meters unless the conversion basis is documented.

3Decide the next passUse the worksheet to decide whether the next step is fixture count, LED wattage, lighting level review, or photometric modeling.

Worksheet checklist. Record source basis, review gaps, and assumptions before using the chart result.

Capture area and targetRecord the room area, task-plane basis, selected target, and whether the target was entered in foot-candles or lux.
Capture lumen basisDocument whether lumens came from a lamp, fixture, total fixture group, or calculated room requirement.
Capture follow-upFlag whether fixture photometrics, CU, LLF, owner criterion, glare, or uniformity review is needed before the value becomes a design input.

Common mistakes to avoid. Review these before turning chart current into an equipment decision.

Using total lamp lumens as delivered task-plane lumens without utilization or maintenance context.
Treating average foot-candles as a complete lighting layout without checking distribution and field conditions.
Mixing a raw lumen-per-area estimate with a CU and LLF adjusted result without labeling which basis was used.

Frequently asked questions

These answers explain how to use the chart without turning a quick reference into a final design decision.

Why does the chart show both foot-candles and lux?

Foot-candles are common in U.S. field planning, while lux appears in many photometric files and product documents. The chart keeps both values tied to the same lumen and area inputs.

Can average foot-candles select the final fixture layout?

No. Average foot-candles can screen the room, but fixture spacing, photometric distribution, glare, mounting height, controls, and field verification still matter.