Luminance Converter Online — Free Luminance Converter Tool
CodexFuse Team · 2026-11-01T11:08:33.388Z · 8 min read min read
Convert nits, foot-lamberts, stilbs and cd/m² instantly with the free CodexFuse luminance converter, plus a worked 500-nit display check.
A luminance converter is a free online tool that translates a brightness value from one luminance unit into another, so a specification in foot-lamberts can be compared directly with a requirement in nits. If a display datasheet, lighting catalogue, or projector manual has ever left you wondering whether the numbers actually match, that confusion is what this tool removes.
Luminance is light leaving a surface toward your eye, per unit of area. That is why it matters for screens and signs: two panels can look alike in a showroom yet perform very differently in sunlight, a bright shop, or a dark meeting room.
What Is a Luminance Converter?
A luminance converter is a free online tool that translates a brightness value from one luminance unit into another, such as candela per square metre into nits, foot-lamberts, or stilbs. It removes manual multiplication, decimal errors, and unit confusion, so a display specification can be compared directly against a requirement in seconds.
The tool does one job instantly: enter a value, choose the starting and target units, and read the result. CodexFuse's luminance converter covers 10 units, which matters because older datasheets and international suppliers do not all use the same convention. Note the distinction: luminance is light emitted from a surface, while illuminance is light falling onto one. If your document talks about lux, you need the illuminance converter instead.
Why Do Manufacturers List Brightness in Different Units?
Manufacturers list brightness in different units because display, lighting, and projection industries developed separate conventions over decades, and older datasheets, regional standards, and specialist equipment still use those legacy units. A single screen can therefore be described in nits in one document and foot-lamberts in another, even though both numbers describe the same emitted light.
The result is a buying headache. Three quotes can use three different units, and the cheapest-looking option may simply be quoted in the smallest-sounding unit.
- Legacy datasheets persist: archived specifications keep using foot-lamberts and stilbs long after nits became the common consumer term.
- Industries diverge: cinema, aviation, medical imaging, and outdoor signage each inherited a preferred unit from earlier equipment.
- Marketing hides the maths: a large number in one unit can look more impressive than the identical output expressed in another unit.
Luminance Units Compared
Anchor on one fact: one nit equals one candela per square metre. A foot-lambert is around 3.426 candela per square metre, and a stilb is 10,000, which is why stilb figures usually look tiny beside nit figures for the same display.
| Unit | Value in candela per square metre | Where you meet it |
|---|---|---|
| Nit | 1 | TV, monitor, and phone specifications |
| Candela per square metre | 1 | Technical datasheets and standards |
| Foot-lambert | around 3.426 | Older display and projection documents |
| Stilb | 10,000 | Specialist and legacy optical references |
| Lambert | around 3,183 | Legacy photometric tables |
Read the table from right to left when checking a purchase: find where the number came from, confirm its unit, and only then convert. A value of 150 foot-lamberts sounds modest next to 500 nits, yet it converts to more than 500 nits, as shown below.
Always write the unit next to the number in notes, quotes, and client emails. A bare "500" means nothing for brightness, and most conversion mistakes start when the unit gets dropped from a forwarded message.
How Do You Use a Luminance Converter Correctly?
To use a luminance converter correctly, enter the value exactly as printed on the datasheet, select the unit shown on that datasheet as the source, select the unit your requirement uses as the target, and read the converted result before deciding. Double-check the source unit first, because converting from the wrong starting unit produces a confident but incorrect answer.
The CodexFuse tool keeps the steps short, matching its own tool page: enter a value, choose units, and see the result instantly in your browser. In practice:
- Sign in if prompted: the tool page asks you to log in or create a free account before use, so do that before you are mid-call with a supplier.
- Enter the value exactly: type the number as printed, including decimals, rather than rounding first. Rounding before conversion compounds the error.
- Choose source, then target: pick the datasheet unit first, then the unit in your brief, and record the result with its unit attached.
For an expensive decision, convert back as a sanity check; if the round trip misses your starting value, a unit selection was wrong.
Worked Example: Checking a 500-Nit Display Spec
Fictional scenario: Sara runs a small signage studio and has quoted a client for an outdoor menu board that must stay readable in daylight. Her brief sets a minimum of 500 nits. Two suppliers reply in other units.
Supplier A lists 150 foot-lamberts. Sara enters 150 in the free converter, selects foot-lambert to nit, and gets around 513.9 nits (150 × 3.426 = 513.9). The panel passes, but only just, so Sara flags the thin margin for a sun-facing window.
Supplier B lists 0.05 stilb. That converts to 0.05 × 10,000 = 500 candela per square metre, exactly 500 nits. It meets the brief on paper with zero headroom, so Sara asks about dimming, viewing angle, and brightness after a year outdoors instead of assuming either panel is comfortably bright. Without conversion, both quotes looked incomparable. With it, Sara compares like with like and avoids a washed-out board at midday.
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Get Started with CodexFuseA converted number proves the units match, not that the panel will look good in your room. Ambient light, reflections, and viewing angle all affect readability, so treat conversion as a pass-or-fail spec check, then confirm the shortlisted panel in realistic light before ordering in bulk.
Where Luminance Conversions Actually Matter
- Outdoor and shop signage: brightness decides whether a menu board or window display is readable at noon or invisible in glare.
- Office and studio fit-outs: matching screens avoids one washed-out display beside a vivid one in the same room.
- Design and colour work: a designer checking a display spec may also adjust images with an image brightness adjuster, an image contrast adjuster, or a hex to CMYK converter before final output.
What This Tool Does Not Do
A converter does not measure your screen, test it in your lighting, or tell you whether 500 nits is enough for your room. It converts a number you already have. If the datasheet figure is optimistic or measured under ideal conditions, conversion will faithfully reproduce that optimism in another unit. Peak brightness, uniformity, and viewing angle are separate figures, so read the rest of the datasheet before committing.
The same logic applies to a studio's IT. Sara's business needs a website that stays up, email that delivers quotes, and backups that survive a failed drive. On CodexFuse: create one account, add credits only for the services you use, choose managed hosting, business email, and backups, and let the managed team handle setup, migration, and monitoring — no subscription stack, no server to babysit.
If unit confusion keeps slowing down spec checks, read our guide to the illuminance converter next, so you never mix up light falling on a surface with light leaving one again.
Frequently Asked Questions
What is the difference between a nit and a candela per square metre?
None numerically. One nit is defined as one candela per square metre, so 500 nits and 500 cd/m² describe exactly the same luminance. Nit is simply the shorter name used in consumer display specifications.
How many nits are in one foot-lambert?
Around 3.426 nits. So 100 foot-lamberts converts to around 342.6 nits. Confirm the source unit first, because foot-lamberts and lamberts are different units with very different values.
Is higher luminance always better?
Not always. Higher luminance helps outdoors and in bright rooms, but in a dark room it can cause eye strain and washed-out blacks. Match brightness to the room.
Can I convert luminance without a tool?
Yes, by multiplying by the right factor, such as 3.426 for foot-lamberts to nits. A tool still helps by removing decimal slips and handling less common units.
Why does my converted value not match the supplier's figure?
Small gaps usually come from rounding, such as 3.426 rounded to 3.43. Large gaps usually mean the source unit was misread or the wrong panel variant was quoted. Ask the supplier to confirm the unit.
Is the CodexFuse tool free?
Yes. The tool page describes it as a free online converter with instant results across 10 units. Note that it asks you to log in or create a free account to use it.
Stop Second-Guessing Brightness Specs — and Simplify the Rest of Your IT
Brightness specs should take seconds to verify. Convert the number, record it with its unit, check the margin honestly, and move on.
Then apply the same standard to your IT. Move your website hosting, business email, and backups to CodexFuse today: create your account, add credits for only what you use, and let a fully managed team handle setup, migration, and monitoring. No subscriptions, no surprise bills, no server babysitting. Convert your next spec now, then get started with CodexFuse.
