Enter a lux or nits value to convert between illuminance and luminance. Leave one field empty and the calculator will solve for it.
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Lux to Nits Formula
The formula below converts lux (illuminance) to nits (luminance), assuming a perfectly diffuse Lambertian surface.
L_{nits} = E_{lux} / \piVariables:
- L = luminance (nits / cd/m²) – light leaving the surface toward the observer
- E = illuminance (lux) – light arriving at the surface
To convert lux to nits, divide lux by pi (3.14159). To convert nits to lux, multiply nits by pi.
| Lux (lx) | Nits (cd/m²) |
|---|---|
| 1 | 0.318 |
| 5 | 1.592 |
| 10 | 3.183 |
| 20 | 6.366 |
| 50 | 15.915 |
| 100 | 31.831 |
| 200 | 63.662 |
| 500 | 159.155 |
| 1000 | 318.310 |
| 2000 | 636.620 |
| 5000 | 1591.549 |
| 10000 | 3183.099 |
| 20000 | 6366.198 |
| 50000 | 15915.494 |
| * L = E / π. 1 fc = 10.7639 lx; 1 nit = 1 cd/m². | |
Lux vs. Nits: What Each Measures
Lux and nits measure fundamentally different quantities. Lux counts light arriving at a surface; nits count light leaving a surface toward the viewer. A lux meter points at the light source; a luminance meter points at the surface being measured.
| Property | Lux (lx) | Nits (cd/m²) |
|---|---|---|
| Quantity | Illuminance | Luminance |
| What it counts | Light hitting a surface | Light leaving a surface |
| SI unit | lm/m² | cd/m² |
| Meter orientation | Sensor faces light source | Sensor faces observed surface |
| Surface-dependent? | No | Yes (reflectance or emission) |
| Typical instrument | Lux meter | Luminance meter / colorimeter |
| Common use | Lighting design, photography exposure | Display calibration, signage spec |
Real-World Lux Environments and Nit Equivalents
The table below maps common ambient lux levels to their Lambertian nit equivalents and indicates the minimum display brightness needed for comfortable viewing in each environment.
| Environment | Typical Lux | Equivalent Nits | Min. Display Brightness |
|---|---|---|---|
| Moonlit night | 0.1 | 0.03 | Any display readable |
| Candlelight | 10 | 3.2 | Any display readable |
| Dim indoor room | 50 | 15.9 | Any display readable |
| Standard office | 500 | 159 | 200 nits |
| Bright office / classroom | 1,000 | 318 | 300 nits |
| Overcast outdoor | 10,000 | 3,183 | 1,000+ nits |
| Open shade outdoors | 20,000 | 6,366 | 3,000+ nits |
| Direct sunlight | 100,000 | 31,831 | Most displays unreadable |
| * Nit equivalents via L = E / π. Display thresholds are approximate comfort minimums. | |||
Display Brightness Tiers by Device Type
Nit ratings determine where a display can be used effectively. The table below covers industry-standard brightness tiers from cinema to outdoor signage.
| Device / Standard | Typical Peak Nits | Intended Environment |
|---|---|---|
| Cinema projector screen (SMPTE) | 48 | Dark theater |
| Budget laptop / monitor | 200–250 | Dim indoors |
| Standard monitor | 300–400 | Typical office (500 lux) |
| VESA DisplayHDR 400 | 400 peak | Entry HDR, dim indoors |
| Standard OLED TV | 400–600 | Dim to moderate indoor |
| VESA DisplayHDR 600 | 600 peak | Moderate HDR |
| Premium LCD TV (HDR) | 700–1,500 | Bright living room |
| VESA DisplayHDR 1000 | 1,000 peak | True HDR content |
| QD-OLED / MLA OLED | 1,500–2,500 | Bright rooms, HDR highlights |
| Apple Pro Display XDR | 1,600 peak / 1,000 full-screen | Studio color grading |
| Smartphone (premium) | 1,000–2,000 | Outdoor readability |
| Indoor digital signage | 1,500–3,000 | Retail, transit |
| Outdoor digital signage | 3,000–10,000 | Direct sunlight visibility |
| * Peak nit ratings for HDR displays apply to a 10% screen area window measurement. | ||
The Lambertian Surface Assumption
The formula L = E / pi assumes a perfect Lambertian (diffuse) reflector: a surface that scatters incoming light equally in all directions with no specular component. Under this assumption, luminance is constant regardless of viewing angle, and the pi factor emerges from integrating the cosine-weighted hemisphere of reflected light over 2 steradians.
Real surfaces deviate substantially. Matte white paper is close to Lambertian (reflectance near 0.9). Glossy screens, polished metals, and most display panels are not. Display backlights and optical films create directional output, so measured luminance varies with angle. Use this formula for estimation; direct luminance measurement with a colorimeter is required for display calibration, cinematography exposure work, or lighting compliance testing.
How to Convert Lux to Nits
- Measure or obtain the illuminance in lux (lx) using a lux meter.
- Divide the lux value by pi (3.14159).
- The result is luminance in nits (cd/m²), valid for a Lambertian surface.
Example: A photography subject is lit to 500 lux. The equivalent surface luminance is 500 / 3.14159 = 159.15 nits. A display reproducing that subject at 160 nits will appear perceptually matched under the same ambient lighting conditions.
