Temperature readings are different from temperature changes
Use the absolute or difference mode that matches the question.
Two scales have different zero points
An absolute Celsius reading converts to Fahrenheit by multiplying by 9/5 and adding 32. The added offset aligns the scales’ zero points. A temperature change does not contain that offset: a rise of 10 °C is a rise of 18 °F. UnitTidy provides separate choices so you do not accidentally add 32 to a difference.
Check the same numbers in both contexts
A room at 20 °C is at 68 °F. If it warms to 30 °C, the new reading is 86 °F and the change is 18 °F. The equivalent absolute readings in kelvin are 293.15 K and 303.15 K; the difference is 10 K. This paired example is useful for checking a spreadsheet formula that appears to give plausible but wrong results.
20 °C → 68 °F → 293.15 K
30 °C → 86 °F → 303.15 K
Δ10 °C → Δ18 °F → Δ10 KReport the measurement honestly
A calculator can display many decimal places, but it cannot improve a thermometer’s accuracy. Choose output precision appropriate to the source and make clear whether a tolerance is a change or an absolute temperature. Physical temperature calculations should also respect the valid range of the selected scale. Keep the unrounded value for intermediate calculations and round the reported result once at the end.