Combined environmental stress

Temperature-Humidity Acceleration Calculator

Combine an Arrhenius temperature term with a relative-humidity power term and translate target use exposure into accelerated test hours.

Temperature-humidity inputs

Enter absolute temperatures in kelvin, relative humidity in percent, and mechanism-supported exponents.

What this calculator does

It multiplies a thermally activated Arrhenius factor by a relative-humidity ratio raised to a fitted exponent, then divides target use exposure by the combined factor.

When to use it

Use it for a degradation mechanism whose rate is supported by both temperature and humidity terms, such as a validated corrosion or moisture-related model. It is not a universal substitute for a humidity-bias qualification standard.

Inputs and formula

Temperatures use kelvin; relative humidities are percentages used as a ratio; activation energy is in eV. Both accelerated conditions must exceed their use conditions.

AF = exp[(Ea / k) × (1 / Tuse − 1 / Ttest)] × (RHtest / RHuse)γ

Worked example and interpretation

At 298.15 K and 40% RH in use, 358.15 K and 85% RH in test, 0.7 eV activation energy, humidity exponent 2.7, and 10,000 target hours, AF is about 734.735 and equivalent test duration is about 13.610 hours.

Practical notes and limitations

Very large factors are especially sensitive to parameter error and competing mechanisms. Confirm condensation behavior, chamber control, material limits, voltage or bias conditions, and whether temperature and humidity effects are separable. This point result includes no confidence bound or distribution fit.