FreeTools Labs Glossary
Running, pace and times
Learn how pace, time, distance and speed relate, and how target times or splits are derived mathematically.
Relevant tool
Running Pace Calculator
Calculate pace, finish time, distance and splits.
Open Running Pace Calculator →The running calculator solves mathematical relations between distance, time, pace and speed. It can also calculate target times, distances, splits and the difference between two paces on the same distance; it makes no training, race or performance prediction.
What the tool calculates
The running calculator solves mathematical relations between distance, time, pace and speed. It can also calculate target times, distances, splits and the difference between two paces on the same distance; it makes no training, race or performance prediction.
Inputs and public functions
The five public modes are `PACE`, `TARGET_TIME`, `DISTANCE`, `SPLITS` and `COMPARE`. Distances are handled internally in metres and times in seconds. Custom distance accepts m, km or mi; pace accepts min/km or min/mi; results show both pace units, km/h and mph without turning them into physiological data.
Calculation model
`PACE` derives pace and speed from distance and total time. `TARGET_TIME` uses distance and pace; `DISTANCE` uses time and pace. `SPLITS` allocates a total time to a chosen interval, and `COMPARE` calculates two target times plus pace and total-time differences for the same entered distance.
Implemented relation
pace (s/km) = time (s) ÷ (distance (m) ÷ 1000); speed (km/h) = distance (m) ÷ time (s) × 3.6; time (s) = distance (km) × pace (s/km).How the model works
One mile is exactly 1,609.344 m. A pace per mile equals pace per kilometre × 1.609344. The presets are 400 m, 800 m, 1 km, 1 mile, 3/5/10 km, half marathon 21.0975 km, marathon 42.195 km, 50 km and 100 km. Time minutes and seconds must each be 0–59; invalid inputs are rejected.
Checked examples
10 km in 50:00 gives 300 s/km, displayed as 5:00 min/km, plus 482.8032 s/mi, 12 km/h and about 7.4565 mph. A half marathon at 5:30 min/km gives 21.0975 × 330 = 6,962.175 s, displayed as 1:56:02.2. For 5 km in 25:00 with 2-km splits, the service returns 2 km in 10:00, another 2 km in 10:00 and the remaining 1 km in 5:00.
How to read the result
Even splits keep one calculated pace. A negative split makes the second exactly equal half faster by the chosen total pace difference; a positive split makes it slower, while preserving total time mathematically. A remaining distance becomes its own final split. `COMPARE` only contrasts the two entered paces; for 10 km at 5:00 and 4:30 it yields 50:00, 45:00 and a five-minute difference.
Assumptions and special cases
Decimal seconds remain in the service until display. `formatDuration` rounds only for output: 59 s is 0:59, 61 s is 1:01, 3,599 s is 59:59 and 3,600 s is 1:00:00. At most 1,000 split rows are materialised; a smaller interval that would exceed this limit produces an error.
Scope and limits
The model has no terrain, wind, temperature, pauses, fatigue, training state, heart rate, GPS, map, calories, VO2max/VDOT or health assessment. Pace, target time, distance and split output are conversions of the entered values, not a realistic performance forecast.