Positive shift: CTO
Use an orange or warming correction when the target Kelvin is lower than the source. Example: 6500 K to 3200 K is approximately +158.65 mired.
Color Temperature Converter — Kelvin, Mired & Gel Correction
Source and target
Quick presets
No input tracking: calculations, copying, and downloads are produced locally on this device.
Correction result
Closest reference gel option
½ CTO + ⅛ CTO
Combined reference shift: +135 mired
Required mired shift+133.93 mired
Correction directionWarm / CTO
Source5600 K · 178.57 mired
Target3200 K · 312.5 mired
The reference stack projects approximately 3189 K, leaving a −1.07 mired residual to the target. Verify the real source and gel before a critical match.
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Reference gel comparison
Matches are ranked by residual mired shift. Published shifts are product references, not universal values for every gel brand or light spectrum.
| Option | Reference shift | Projected result | Residual to target |
|---|---|---|---|
| ½ CTO + ⅛ CTO | +135 mired | 3189 K | −1.07 mired |
| ½ CTO | +109 mired | 3477 K | +24.93 mired |
How to use this color temperature converter
- Enter the source. Use a fixture rating or, preferably, a measured correlated color temperature. Select Kelvin or mired beside the value.
- Enter the target. This may be a camera balance, another fixture, or the intended corrected light temperature.
- Read the signed shift. A positive result means warming correction toward lower Kelvin; a negative result means cooling correction toward higher Kelvin.
- Compare the gel options. The first row checks one- and two-gel combinations. The second row always shows the nearest single reference gel.
- Test the physical result. Product batches, age, heat, fixture spectrum, dimming, and stacked gels can move the real result away from the arithmetic.
Kelvin, mired, and correction formulas
Kelvin is not a linear correction scale. A 500 K change near tungsten is much larger in reciprocal-temperature terms than a 500 K change in high daylight. Mired—short for micro reciprocal degree—makes these lighting corrections easier to compare.
mired = 1,000,000 ÷ kelvin
kelvin = 1,000,000 ÷ mired
required mired shift = target mired − source mired
Adding a positive mired shift increases the reciprocal value and therefore lowers Kelvin, producing a warmer result. Adding a negative shift lowers the reciprocal value and raises Kelvin, producing a cooler result.
Negative shift: CTB
Use a blue or cooling correction when the target Kelvin is higher than the source. Example: 3200 K to 5700 K is approximately −137.06 mired.
CTO and CTB reference shifts
The calculator uses the following published LEE Filters values to make its reference comparisons. Fractional names do not represent an exact linear fraction of the full filter's mired shift, so the listed values—not the fraction labels—drive the matching calculation.
| Correction | Reference product | Published mired shift | Published example |
|---|---|---|---|
| Full CTO | LEE 204 | +159 | 6500 K to 3200 K |
| ½ CTO | LEE 205 | +109 | 6500 K to 3800 K |
| ¼ CTO | LEE 206 | +64 | 6500 K to 4600 K |
| ⅛ CTO | LEE 223 | +26 | 6500 K to 5550 K |
| Full CTB | LEE 201 | −137 | 3200 K to 5700 K |
| ½ CTB | LEE 202 | −78 | 3200 K to 4300 K |
| ¼ CTB | LEE 203 | −35 | 3200 K to 3600 K |
| ⅛ CTB | LEE 218 | −18 | 3200 K to 3400 K |
Technical references: LEE Filters product data for Full CTO, Half CTO, Quarter CTO, Eighth CTO, Full CTB, Half CTB, Quarter CTB, and Eighth CTB. Kodak's Wratten filter tables independently publish conversion temperatures and signed mired shifts and caution that filtration values are approximate.
Worked color-temperature examples
| Source → target | Source mired | Target mired | Required shift | Direction |
|---|---|---|---|---|
| 6500 K → 3200 K | 153.85 | 312.5 | +158.65 | Warm / CTO |
| 5600 K → 3200 K | 178.57 | 312.5 | +133.93 | Warm / CTO |
| 3200 K → 4300 K | 312.5 | 232.56 | −79.94 | Cool / CTB |
| 3200 K → 5700 K | 312.5 | 175.44 | −137.06 | Cool / CTB |
Assumptions and practical limits
This calculator treats the entered values as ideal correlated color temperatures and models gel shifts by addition on the mired scale. A real source is a spectrum, not just a Kelvin number. Two fixtures can share a CCT while differing in spectral power distribution, green-magenta tint, color rendering, output, and camera response. Gel also absorbs light; this tool does not calculate exposure loss.
Stacked-gel shifts are added as a planning approximation. Transmission curves interact, and heat, fading, angle, fixture optics, dimming, and product variation can change the result. For matching cameras, LEDs, discharge sources, or critical color work, check the manufacturer's current data and measure the corrected light with a suitable color meter or spectrometer.
Color temperature converter FAQ
What is a mired?
A mired is one million divided by color temperature in kelvins. Because it is reciprocal, the scale better reflects the size of color-temperature corrections across warm and cool sources.
How do I convert Kelvin to mired?
Divide 1,000,000 by the Kelvin value. The same formula in reverse converts mired to Kelvin: 1,000,000 divided by mired.
What do positive and negative mired shifts mean?
A positive shift moves toward a lower, warmer color temperature and normally calls for CTO-type correction. A negative shift moves toward a higher, cooler color temperature and normally calls for CTB-type correction.
What gel corrects 5600 K to 3200 K?
The exact arithmetic is approximately +133.93 mired. That does not map universally to one gel name because manufacturers publish different shifts. This page compares specific reference values and shows the projected residual so you can choose a starting point, then test the actual source and material.
Does the same Kelvin value guarantee two lights will match?
No. CCT compresses a complex spectrum into one value. Green-magenta tint, spectral gaps or peaks, color rendering, fixture age, dimming, and camera spectral response can still make nominally equal-CCT lights look different.
Is camera white balance the same as correcting a light with gel?
No. White balance changes the camera's interpretation of the complete scene. Gel changes the spectrum of one physical source before it reaches the subject. White balance cannot independently align two differently colored sources in the same shot.
Does this tool upload my lighting values?
No. Conversion, matching, clipboard text, and CSV creation run locally in the browser. The page does not send your source or target inputs to a backend.