Mired is the micro-reciprocal degree measure of color temperature: mired = 1,000,000 / kelvin.
Mired shift is the difference between target and source mired: shift = mired_target - mired_source.
If you already have a shift, compute the new target using: mired_new = mired_source + shift, then kelvin_new = 1,000,000 / mired_new.
- Read the kelvin rating from your grow light or LED strip.
- Pick a target kelvin that matches your room plan.
- Submit to view mired values and the shift direction.
- Use a positive shift to warm, negative to cool.
- Download CSV or PDF to log changes per grow zone.
| Source (K) | Target (K) | Mired shift | Interpretation |
|---|---|---|---|
| 4000 | 5000 | -50.00 | Cooler correction for a cleaner white. |
| 6500 | 3000 | +179.49 | Warmer correction for bloom-friendly tone. |
| 3500 | 4000 | -35.71 | Slight cool shift for balanced mixing. |
| 2700 | 2700 | 0.00 | No correction required. |
Why mired matters in grow lighting
Kelvin is perceptual, but mired is linear for correction work. Converting each fixture to mired makes differences comparable across the range. Small kelvin changes at warm whites create large mired changes, while cool whites move less. This helps you predict visible shifts and gel strength.
Choosing a target temperature for crop phase
Select a target that supports your goal, then keep it stable. Vegetative areas often favor cleaner whites for inspection and uniformity. Flower rooms may use warmer targets to balance comfort and leaf sheen. Use one target per zone so measurements, photos, and scouting notes stay consistent.
Interpreting positive and negative shifts
A positive mired shift means the corrected output becomes warmer, adding amber or red bias. A negative shift means the corrected output becomes cooler, adding blue bias. When you compare fixtures, focus on the sign first for direction, then the magnitude to judge how noticeable the change will be.
Managing mixed fixtures and zones
Mixed installations should be evaluated in mired, not kelvin. Convert each light, then compute a weighted average based on wattage or measured PPFD contribution. Use that average as your zone baseline. If you swap one fixture, recompute the baseline to keep the room color balance predictable.
Documentation and repeatability
Consistency is a workflow, not a one-time setting. Record source values, target values, and the final shift after any change to reflectors, dimming, or height. Export a CSV for logs and a PDF for job folders. Over time you will identify which shifts align best with your standards. When using dimmers, log the dimming percentage because spectral balance can drift. If you rely on camera-based crop tracking, recalibrate white balance after any shift so images remain comparable. For multi-tier racks, record height and diffuser placement since reflections influence perceived warmth. Standardizing these details reduces troubleshooting time and improves repeatability during seasonal reconfigurations. Teams can train staff with one simple lighting checklist for consistency.
1) What is a mired shift used for?
It converts color temperature differences into a linear correction value. This is useful when matching fixtures, estimating filter strength, and keeping grow-room lighting consistent across zones.
2) Why can two kelvin changes look different?
Kelvin is not linear for correction. A 500 K change near 3000 K is a bigger correction than 500 K near 6500 K. Mired normalizes that behavior.
3) What does a positive shift mean?
Positive shift means the target mired is higher than the source mired. The correction direction is warmer, which typically increases amber or red appearance.
4) Can I enter a negative mired shift?
Yes. Negative values indicate a cooler correction. The calculator will compute the new target temperature and show the direction clearly.
5) What range of kelvin values should I use?
Most grow and work lights fall between 2700 K and 6500 K, but the calculator accepts a wider range. If the value is extreme, verify the fixture specification.
6) How should I document changes over time?
Keep a per-zone log with date, source kelvin, target kelvin, and shift. Use CSV for spreadsheets and PDF for maintenance records so you can repeat settings after upgrades.