Concrete evaporation rate calculator. See your pour risk in seconds.

A free concrete evaporation rate tool built on the ACI 305R formula. Enter four numbers from your job site and get an instant GO, CAUTION, or WARNING — before the ready-mix truck leaves the yard.

How the calculator works

Evaporation rate measures how fast moisture leaves the surface of fresh concrete, in pounds per square foot per hour. When it climbs faster than bleed water can replace it, the surface dries and shrinks — the cause of plastic shrinkage cracking. The calculator combines air temperature, humidity, wind, and concrete temperature into a single number using the ACI 305R formula.

Reading your result

• GO (below 0.10 lb/ft²/hr). Conditions are favorable. Standard curing practices apply.
• CAUTION (0.10–0.20). Elevated. Use evaporation retarders, windbreaks, fogging, or shift pour timing.
• WARNING (above 0.20). Postpone or aggressively mitigate — you're past the safe limit.

Want the full breakdown of the math and the variables? Read the complete evaporation rate guide or open the in-depth calculator page.