Enter the ACFM into your calculator.
Press the "x" key.
Enter "((psig + 14.7)/14.7)." Replace "psig" with your equipment's gauge pressure. The number 14.7 is the standard atmospheric pressure at sea level. Include all the parentheses in the correct order.
Press the "x" key.
Enter "((68 +460)/(T + 460))." Replace "T" with the actual temperature at the time of testing. This formula uses 68 as the standard temperature in Fahrenheit, but some people use other temperatures when calculating SCFM.
Press "=" to get the SCFM.
Double check your calculation with the complete formula: "SCFM = ACFM x ((psig + 14.7) / 14.7) x ((68 +460) / (T + 460))."