Dev time · temperature compensation
Most charts list times at 20°C. If your chemistry is warmer or cooler, adjust the time so development stays consistent.
General factor for common MQ/PQ developers. For big shifts stay within 18–24°C, and confirm against your developer's own chart.
About this tool
Chart times are usually quoted at 20°C, but darkrooms are rarely that tidy. Enter the published time, the temperature that time assumes, and the actual temperature of your developer. The calculator returns a compensated development time. Warmer developer works faster, so the adjusted time gets shorter; cooler developer needs longer.
How to use it
- Enter the published development time and the chart's reference temperature.
- Measure your developer with a reliable thermometer and enter that actual temperature.
- Read the compensated time, then develop for that length while keeping the temperature steady.
FAQ
How far from 20°C can I safely go?
Compensation works well roughly between 18°C and 24°C. Beyond that the relationship becomes unreliable and grain, contrast and consistency suffer, so it is better to bring the developer back toward the reference temperature.
Does temperature drift during development matter?
Yes. The compensated time assumes a steady temperature. In a warm or cold room use a water bath around the tank, and check the developer before you start so the whole cycle stays close to your entered value.