What is mired and why is it used?

Mired (micro reciprocal degree) is calculated as 1,000,000 / Kelvin. The advantage of mired over Kelvin is that equal mired shifts produce equal perceived colour changes regardless of the starting temperature. A shift of 50 mired always looks the same, whereas a shift of 500K looks very different at 2000K vs 8000K.

What colour temperature is daylight?

Direct midday sunlight is approximately 5200K. Overcast sky is around 6000-6500K (bluer). Open shade under blue sky can be 7500-10000K. Flash units are typically calibrated to 5500K. Golden hour light drops to around 3500-4000K.

What are CTO and CTB filters?

CTO (Colour Temperature Orange) filters warm light by adding positive mired shift. CTB (Colour Temperature Blue) filters cool light by adding negative mired shift. A full CTO converts daylight (5500K) to tungsten (3200K), a shift of about +131 mired. These are used on flash units and studio lights to match ambient colour temperature.

Should I set white balance in camera or in post?

If shooting RAW, white balance can be changed in post-processing with no quality loss — it is simply metadata. However, setting it correctly in-camera gives you accurate preview images and histograms. If shooting JPEG, white balance is baked in and should be set accurately before shooting.

PhotoCalcs

White Balance Calculator — Kelvin & Mired Conversion

Convert between colour temperatures in Kelvin and mired, and find the right colour correction filter.

Light Source

Source colour temperature

Target Kelvin

Desired white balance setting

How We Calculate This

This calculator converts between Kelvin and mired values and suggests correction filters:

Mired Conversion

Mired = 1,000,000 / Kelvin

Mired Shift

Shift = target mired - source mired

Positive shift = warming (towards orange/tungsten). Negative shift = cooling (towards blue/daylight). The calculator suggests the closest standard CTO or CTB gel filter based on the required shift.

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates based on standard optical and photographic formulas. Results may vary with specific equipment.