Leave a plastic lawn chair in the Arizona sun long enough and it slowly sags — even though the load never changes. That slow, permanent stretch under constant stress is creep, and engineers quantify it with the creep rate: the change in strain divided by the elapsed time. In symbols: rate = (εₜ − ε₀) / t. Strain itself is just fractional stretch, so the rate tells you how fast the material is giving up, per hour.

Creep is why solder joints in a hot attic can fail years after installation, why plastic pipes under constant water pressure eventually bulge, and why jet engine turbine blades — spinning at full throttle in 2,000-degree gas — are made from single-crystal superalloys. Room-temperature steel barely creeps, but polymers and high-temperature metals creep enough to matter over months and years.

This calculator turns two strain readings into a rate. Type the earlier strain measurement in the Initial Strain (ε₀) box and the later one in the Final Strain (εₜ) box — as decimals, so 2% stretch is 0.02. Type the hours between readings in the Time Elapsed (hours) box. The Creep Rate (per hour) box reports how fast the material is deforming, the number that decides whether a part lasts decades or months.

With the pre-filled defaults — Initial Strain (ε₀) 0.001, Final Strain (εₜ) 0.005, Time Elapsed (hours) 100 — the Creep Rate Calculator returns Creep Rate (per hour) 0.000040. Change any input and those results update instantly, so you can see exactly how each number you enter moves the answer.