Calculate Process Cycle Time and Percentage Change

Use this calculator

Compare the average elapsed time per completed item in two samples. Calculate the percentage change and review whether the samples are comparable.

Formula and units

Average elapsed time per item = sum of individual elapsed times ÷ completed items. Change (%) = (after average − before average) ÷ before average × 100. If the before average is zero, percentage change is undefined.

Worked example

Before: 100 hours across 20 items = 5 hours/item. After: 60 hours across 20 items = 3 hours/item. Change = −40%, a 40% reduction in average elapsed time.

Inputs and limits

• Sum of individual elapsed times before (hours): 0 to 1000000000.
• Completed items in the before sample: 1 to 1000000000 (whole numbers only).
• Sum of individual elapsed times after (hours): 0 to 1000000000.
• Completed items in the after sample: 1 to 1000000000 (whole numbers only).

The upper bounds are practical input limits for this tool, not professional standards. Enter decimal numbers using a point, without currency symbols, commas or scientific notation.

Assumptions and interpretation

Measure each item from the same start point to the same end point, including waiting if that is in your agreed definition. Add those individual elapsed durations. Do not enter the duration of an operating period divided by its throughput: that measures a different quantity. Use comparable item types and collection rules. Averages hide variation. A zero baseline cannot support a percentage change; a zero after value is allowed but may indicate measurement or rounding problems.

Rounding and data handling

Calculations use the entered values before rounding. Results display to two decimal places. A tiny non-zero result may display as 0.00; review the input units and magnitude. Financial figures are indicative, not accounting entries. Inputs are processed in browser memory only: this calculator does not submit or store them, and reset or reload clears them. Ordinary website page requests still occur. Do not enter personal or confidential information. Without JavaScript, use the formula and worked example above manually.

These are original RDE planning calculators. Related reading provides context, not validation or endorsement of the formulas or input limits.