Two numbers, two different questions
At-load consumption describes the published airflow associated with the tool working under the manufacturer’s test conditions. An average figure incorporates a use pattern or test convention. Those conditions matter: an average cannot automatically be substituted for demand while the trigger is held.
The Ingersoll Rand 231C table illustrates the difference. It lists 22 CFM at load and 4.2 CFM average, alongside 90 PSI. These are two labels for the same tool, not two interchangeable estimates. When the catalog does not explain its averaging schedule, retain that uncertainty.
Build your own schedule
For an illustrative repeating minute, average demand = at-load CFM × trigger seconds ÷ 60 × number of tools. A hypothetical 12 CFM tool operated for 15 seconds each minute averages 3 CFM. Running it for 30 seconds doubles that average to 6 CFM; it still demands the original 12 CFM during each active period.
The calculator makes this schedule explicit. Enter actual at-load consumption if it is published, rather than multiplying an undocumented catalog average by a guessed correction factor. Simultaneous identical tools can be represented by the quantity field.
What a passing average leaves unanswered
A compressor can exceed average demand while falling below the tool’s active demand. The tank, pump cycling and pressure losses then influence each burst. This arithmetic does not establish the available pressure throughout a long trigger pull, or how soon the next burst can begin.
Use the result as one airflow check. Read the compressor’s duty and duration limits separately. If only average or free-speed consumption is available, the match page explains the missing information rather than inventing an at-load value.
A catalog average and an at-load figure answer different questions. Keep the label and operating pressure with every number.