This sheet provides input values for the formula in ASTM C1781 Standard Test Method for Surface Infiltration Rate of Permeable Unit Pavement Systems that calculates that rate in inches per hour. The test also indicates how long water stands on the surface which can indicate when cleaning should be done to prevent clogging. The sheet provides inputs for 8 lbs (5 kg) of water for the wetting step and 40 lbs (18 kg) for the testing step, thereby providing instant answers.