Convert luminance between cd/m² (nit, SI base), stilb (1 = 10000 cd/m²), cd/ft² (1 = 10.76391 cd/m²), foot-lambert (1 = 3.426263 cd/m²), apostilb (1 = 0.31831 cd/m²), lambert (1 = 3183.099 cd/m²), and millilambert (1 = 3.183099 cd/m²). All non-SI units except stilb carry a 1/π factor from Lambertian diffuse-emission assumptions. Reference values: LCD display ≈ 200–300, comfortable eye level ≈ 1000, sun surface ≈ 1.6×10⁹ cd/m².
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Tool usage guide
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Key facts
Category
Math & Numbers
Input types
select, number
Output type
json
Sample coverage
4
API ready
Yes
Overview
Convert luminance values between cd/m² (nit), stilb, cd/ft², foot-lambert, apostilb, lambert, and millilambert. Enter a non-negative value, select the input and output units, and choose the required decimal precision.
When to use
Convert LCD or display brightness from cd/m² (nit) to foot-lambert or another luminance unit.
Compare photometry values reported in SI and traditional luminance units.
Check reference levels such as typical LCD brightness near 200–300 cd/m² or comfortable eye-level luminance near 1000 cd/m².
How it works
1Enter a non-negative luminance value in the Value field.
2Select the unit of the entered value, such as cd/m², nit, foot-lambert, or stilb.
3Choose the output unit for the converted result.
4Set Decimal Places from 0 to 10, then review the converted value and unit values in the JSON result.
Use cases
Display engineering teams can convert monitor brightness specifications between nits, cd/ft², and foot-lamberts.
Photometry students can compare SI and traditional luminance units using consistent conversion values.
HDR and screen calibration workflows can express a luminance reference such as 1000 cd/m² in apostilb, lambert, or millilambert.
Examples
1. Convert LCD brightness to foot-lamberts
Display technician
Background
A display specification lists brightness as 300 cd/m², while a reference document uses foot-lamberts.
Problem
Find the equivalent luminance in foot-lamberts.
How to use
Enter 300 as the value, select cd/m² (nit) as the input unit, choose foot-lambert as the output unit, and leave Decimal Places at 6.