How to use the mired converter
- Under Calculation, choose Convert to change one value, or Filter shift to compare two lights.
- For Convert: type the number in Value and set Unit to Kelvin or Mired. The result shows the other unit and the value in decamired.
- For Filter shift: enter the Light source colour temperature and the Target in kelvin. The defaults are 3,200 K and 5,600 K.
- Read the Mired shift needed, the Filter type, and the table of typical light sources below.
What it does and when to use it
Photographers, video crews and stage lighting designers often mix light sources. A tungsten lamp in a room lit by a window will look orange on camera. To match them you put a coloured gel over one of the lights, and gel charts are written in mireds. This tool turns kelvin values from a lamp spec sheet or a camera’s white balance into mireds, and tells you how big a shift you need.
For on-screen colours rather than lights, the colour temperature tool shows what a kelvin value looks like as a colour. To work with the brightness of the light instead, use the illuminance converter (lux and foot-candles) or the luminance converter.
How it works
- mired = 1,000,000 ÷ kelvin, and kelvin = 1,000,000 ÷ mired. The same formula works both ways.
- Mired shift = 1,000,000 ÷ target − 1,000,000 ÷ source.
A positive shift is labelled “Warming (amber, CTO)”, a negative one “Cooling (blue, CTB)”, and zero “None”. Values must be greater than zero; 0 or a negative number shows a short message instead of a result.
Worked examples
Halogen lamp in mireds. 3,200 K = 312.5 mired, or 31.25 decamired.
Daylight to tungsten. Source 5,600 K, target 3,200 K. The tool shows Mired shift needed: 133.928571429 mired, 13.39 decamired, and “Warming (amber, CTO)”. This is the gel you would put on a daylight LED panel so it matches tungsten lamps.
Warm room to neutral. Source 2,700 K (a typical warm-white bulb), target 4,000 K. The shift is −120.37037037 mired, labelled Cooling (blue, CTB).
Kelvin and mired side by side
| Kelvin | Mired |
|---|---|
| 2,700 | 370.4 |
| 3,200 | 312.5 |
| 4,000 | 250 |
| 5,600 | 178.6 |
| 6,500 | 153.8 |
Equal steps in kelvin are not equal steps in mired. Going from 2,700 K to 3,200 K is a 58-mired change, while 5,600 K to 6,500 K is only 25 mired, even though the second gap in kelvin is bigger.
Limits and tips
- Colour temperature is not the whole story. Many LED and fluorescent lamps also have a green or magenta tint, which mireds do not measure. That needs a separate plus-green or minus-green filter.
- The tool does not know specific gel products or their published values.
Frequently asked questions
What is a mired?
Why use mireds instead of kelvin for filters?
Does a positive shift mean warming or cooling?
Which gel gives exactly −133.9 mired?
Are the values in the sources table exact?
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