Luminance / Illuminance Converter
Convert luminance and illuminance units online for free. Our luminance illuminance converter supports lux, foot-candle, phot, nox, nit, candela/m², foot-lambert, stilb, apostilb, lambert, and more. Instant results, no signup required — all conversions run locally in your browser.
Select your source and target units, enter a value, and click Convert. All conversions run instantly in your browser — your data never leaves your device.
Illuminance Quick Reference
Luminance Quick Reference
Why Use Our Luminance / Illuminance Converter?
Instant Luminance / Illuminance Conversion
Convert between lux, foot-candle, nit, candela/m², foot-lambert, stilb, apostilb, lambert, and more in milliseconds. Our luminance illuminance converter processes every calculation instantly in your browser — zero wait time.
Secure Luminance Illuminance Converter Online
All conversions run 100% locally in your browser. Your values never leave your device — use our luminance illuminance converter online with complete privacy and zero data collection.
Luminance Illuminance Converter — No Installation
Use our luminance illuminance converter directly in any browser with no downloads, plugins, or app installs required. Convert lux to foot-candle, nit to foot-lambert, or any other pair from any device, anywhere.
All-Units Result Table
See your value converted to all units in the same group simultaneously — illuminance or luminance — in a single result table. Plus, quick-reference buttons for real-world values like office lighting, direct sunlight, and LCD screens.
Common Use Cases for Luminance / Illuminance Converter
Architectural & Interior Lighting Design
Lighting designers and architects use lux and foot-candle values to meet building codes and occupancy standards. Our luminance illuminance converter lets you instantly translate lux specifications from international standards into foot-candles for US projects.
Photography & Cinematography
Photographers and cinematographers work with foot-candles and lux when calibrating light meters and setting exposure. Convert lux to foot-candle or foot-lambert to nit to match your camera sensor specifications and lighting equipment ratings.
Display & Screen Engineering
Display engineers specify screen brightness in nits (cd/m²) or foot-lamberts. Use our luminance illuminance converter to translate nit ratings between standards, compare monitor brightness specs, and verify HDR display requirements.
Industrial & Workplace Safety
OSHA and ISO workplace lighting standards specify minimum illuminance levels in lux or foot-candles depending on the region. Convert between these units to ensure your facility meets the required luminance illuminance standards for worker safety.
Scientific Research & Photometry
Researchers in photometry, optics, and vision science work with stilb, apostilb, lambert, and candela/m² units. Our luminance illuminance converter handles all CGS and SI photometric units with full precision for academic and laboratory use.
Smart Building & IoT Sensor Integration
Smart building systems and IoT light sensors often output lux values that need to be converted for dashboards, automation rules, or compliance reports. Convert lux to foot-candle or nit values instantly for any integration workflow.
Understanding Luminance and Illuminance Conversion
What is Luminance vs. Illuminance?
Illuminance measures how much luminous flux falls on a surface per unit area — it describes how brightly a surface is lit. The SI unit is the lux (lx), equal to one lumen per square metre. The US customary unit is the foot-candle (fc), equal to one lumen per square foot. Luminance, by contrast, measures the intensity of light emitted or reflected from a surface in a given direction per unit area — it describes how bright a surface appears to an observer. The SI unit is candela per square metre (cd/m²), also called the nit. Our luminance illuminance converter handles both quantities across all major photometric units.
How Our Luminance / Illuminance Converter Works
- 1.Select your units: Choose the source unit (From) and the target unit (To) from the dropdowns. The converter automatically keeps both units in the same physical quantity group — illuminance or luminance — to prevent invalid conversions.
- 2.Enter your value: Type any non-negative number. Luminance and illuminance values are always ≥ 0 — the converter validates this automatically.
- 3.Get instant results: Click Convert to see the result and a full all-units table showing your value in every unit within the same group simultaneously.
Illuminance Units Explained
| Unit | Symbol | Equivalent in Lux |
|---|---|---|
| Lux | lx | 1 lx |
| Foot-candle | fc | 10.7639 lx |
| Phot | ph | 10,000 lx |
| Nox | nx | 0.001 lx |
Luminance Units Explained
| Unit | Symbol | Equivalent in cd/m² |
|---|---|---|
| Candela/m² | cd/m² | 1 cd/m² |
| Nit | nt | 1 cd/m² |
| Foot-lambert | fL | 3.42626 cd/m² |
| Stilb | sb | 10,000 cd/m² |
| Apostilb | asb | 1/π ≈ 0.3183 cd/m² |
| Lambert | La | 10,000/π ≈ 3183.1 cd/m² |
| Candela/ft² | cd/ft² | 10.7639 cd/m² |
| Candela/cm² | cd/cm² | 10,000 cd/m² |
Key Conversion Formulas:
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Frequently Asked Questions About Luminance / Illuminance Converter
A luminance illuminance converter is a tool that transforms a light measurement value from one photometric unit to another within the same physical quantity. Our luminance illuminance converter supports illuminance units (lux, foot-candle, phot, nox) and luminance units (cd/m², nit, foot-lambert, stilb, apostilb, lambert, cd/ft², cd/cm²) — all processed instantly in your browser with no signup required.
Illuminance measures how much light falls on a surface (lux, foot-candle) — it describes how brightly a surface is lit from an external source. Luminance measures how much light is emitted or reflected from a surface toward an observer (cd/m², nit) — it describes how bright a surface appears. You cannot directly convert between the two without knowing the surface reflectance.
To convert lux to foot-candle, divide by 10.7639: fc = lx ÷ 10.7639. For example, 500 lux = 46.45 foot-candles. This is because one foot-candle equals one lumen per square foot, and one square foot equals 0.0929 square metres. Our luminance illuminance converter applies this formula automatically.
To convert nit (cd/m²) to foot-lambert, divide by 3.42626: fL = cd/m² ÷ 3.42626. For example, a typical LCD monitor at 250 cd/m² = 73 fL. Our luminance illuminance converter handles this conversion instantly — just select cd/m² as the source and foot-lambert as the target.
A nit is simply an informal name for candela per square metre (cd/m²). They are exactly equal: 1 nit = 1 cd/m². The term "nit" is commonly used in the display industry to describe screen brightness. A typical laptop screen is 250–400 nits, while HDR displays can reach 1,000–10,000 nits.
Yes, completely. All conversions run 100% locally in your browser using JavaScript. Your values are never sent to any server, stored, or logged. Use our luminance illuminance converter online with full confidence in your privacy.
Yes. Our luminance illuminance converter is 100% free with no signup, no account, no premium tier, and no usage limits. Convert luminance and illuminance values as many times as you need — completely free, forever.
Common illuminance values: moonless night ≈ 0.001 lux, full moon ≈ 1 lux, office lighting ≈ 500 lux, overcast day ≈ 1,000 lux, direct sunlight ≈ 100,000 lux. Common luminance values: night sky ≈ 0.001 cd/m², LCD screen ≈ 250 cd/m², fluorescent lamp ≈ 10,000 cd/m², the sun at noon ≈ 1.6 × 10⁹ cd/m².
All three are CGS luminance units. A stilb (sb) equals 10,000 cd/m² — it is the CGS equivalent of cd/cm². An apostilb (asb) equals 1/π cd/m² ≈ 0.3183 cd/m² — it represents the luminance of a perfectly diffuse (Lambertian) surface emitting one lumen per square metre. A lambert (La) equals 10,000/π cd/m² ≈ 3,183 cd/m² — the CGS equivalent of the apostilb scaled to cm².