Calculate running pace, elapsed time, or distance for miles and kilometers.
Choose the missing variable
Use the mode that matches the question: time for a known distance and pace, pace for a known distance and time, or distance for a known time and pace. Keep the distance unit fixed while comparing scenarios. Do not paste a decimal-minute pace into separate minutes/seconds fields without converting its fractional portion. The result does not adjust for terrain, stops, or pacing variation.
Inputs and method
Choose whether to solve pace, elapsed time, or distance, then enter the other two quantities. The calculator works in raw seconds and uses the exact international mile conversion of 1.609344 kilometers.
Interpreting the estimate
Use the result as a planning value and keep input precision consistent with the measurements or source data you have. Small displayed differences can come from final-place rounding; intermediate values are not rounded.
Assumptions and limits
Display rounding does not change intermediate values. Stops, course measurement, terrain, and conditions are outside the arithmetic.
Rejecting empty, invalid, prohibited negative, zero-denominator, impossible, or unsupported inputs prevents the page from presenting a misleading numeric result.
Method basis
The pace, time, and distance equations are publisher derivations. Distance conversion uses exactly 1 mile = 1.609344 kilometers. For race splits and unit switching, pair this with the half marathon pace calculator and the pace converter calculator; for a similar pace-per-distance tool in another sport, see the swimming speed calculator.