Footcandles Explained: Sports Lighting Light Levels

A footcandle (fc) is one lumen of light falling on one square foot of surface. It is the standard US measure of how much light actually reaches a field, court, or floor — and it is the number every sports lighting design is built around. Targets are set in maintained footcandles by sport and class of play, from about 30 fc for recreation to 50 fc for competition and 100+ fc (plus high vertical footcandles) for broadcast. Get the footcandle target right and everything else follows; get it wrong and the project is either dim and unusable or wastefully over-built.

This guide explains exactly what a footcandle measures, how it differs from the lumens printed on a fixture box and the lux used overseas, why "maintained" and "vertical" footcandles matter more than the headline number, and how the right target gets chosen for your facility.

What a footcandle actually measures

Lighting has two very different quantities that are easy to confuse. Luminous flux, measured in lumens, is the total amount of light a fixture produces in every direction. Illuminance, measured in footcandles, is how much of that light lands on a specific surface. A 100,000-lumen fixture aimed at the sky delivers zero useful footcandles to the field; a smaller, well-aimed fixture can deliver more usable light exactly where players need it.

That distinction is the whole game in sports lighting. You buy lumens, but you design to footcandles. A specification that promises a certain wattage or lumen package without committing to maintained footcandles on the playing surface is promising the wrong thing.

Footcandles vs lux vs lumens

The practical takeaway: footcandles and lux describe the same thing in different units (1 fc ≈ 10.76 lux), and both describe delivered light. Lumens describe the source. When you compare two designs, compare the maintained footcandles each delivers to the field — not the lumen output of the fixtures, which says nothing about aiming, optics, or losses.

Maintained vs initial — why the lower number is the honest one

Every lighting system gets dimmer over time. Lenses collect dust, LEDs slowly lose output (tracked as L70 — the hours until a fixture falls to 70% of initial lumens), and ambient temperature affects performance. Initial footcandles describe opening night; maintained footcandles describe the level after that expected depreciation, which a designer accounts for with a light loss factor.

Reputable sports lighting is always designed to maintained values, so the field still meets its IES RP-6 target years into service rather than only on day one. If a quote brags about a high footcandle number, ask whether it is initial or maintained — the honest, design-relevant figure is maintained.

Horizontal vs vertical footcandles

Two orientations matter. Horizontal footcandles measure light on the flat playing surface — the baseline number for most recreational and competition fields. Vertical footcandles measure light on a vertical plane: the players, and crucially the ball in flight. Vertical illuminance is what lets athletes track a fly ball or a fast serve, and it is essential for broadcast, where cameras see the vertical plane and need consistent light on faces and the ball.

Lower classes of play are designed primarily to horizontal footcandles. As you move up toward competition and broadcast, vertical footcandle targets are added and become the harder design constraint.

How the right target gets chosen

The exact footcandle target is not a guess — it comes from the IES RP-6 class of play for your sport and level of use. Recreational softball, a high-school football stadium, and a televised collegiate field have very different targets for footcandles, uniformity, and vertical illuminance. Designing above your actual class wastes capital and energy; designing below it produces a field that feels dim and uneven no matter how many fixtures are installed.

A photometric study converts the target into a real layout: fixture count, optics, aiming, and pole positions that deliver the maintained footcandles and uniformity your class of play requires. Duvon designs every layout to maintained RP-6 targets.

Frequently asked questions

What is a footcandle?

One lumen of light falling on one square foot of surface — the standard US measure of how much light actually reaches a field or court, as opposed to how much a fixture emits.

What is the difference between footcandles, lux, and lumens?

Lumens measure total light emitted by a fixture; footcandles and lux measure light landing on a surface. 1 fc = 1 lumen/ft² ≈ 10.76 lux. Lux is the metric version of the footcandle.

What are maintained footcandles?

The light level after normal depreciation (dirt and gradual LED lumen loss), not opening-night brightness. Sports lighting is designed to maintained values so the target still holds years later.

What is the difference between horizontal and vertical footcandles?

Horizontal footcandles light the flat playing surface; vertical footcandles light players and the ball in flight. Vertical illuminance matters most for ball tracking and broadcast.

How many footcandles does my field need?

It depends on the sport and IES RP-6 class of play — roughly 30 fc recreational, 50 fc competition, and 100+ fc (plus vertical) for broadcast. A photometric study confirms the target and the layout to hit it.

Get a free certified photometric layout that shows the maintained footcandles and uniformity your field will achieve. Request it at duvonlighting.com/photometric-study.