{"success":true,"version":"v1","request":{"tool":"get_calculator_schema","calculator_id":"running-pace"},"result":{"entity_type":"calculator","id":"running-pace","calculator_id":"running-pace","canonical_url":"https://tttkmbb.com/fitness/running-pace","name":"Running Pace Calculator","title":"Running Pace Calculator – Pace per km and mile, Speed and Race Splits from Distance and Time","category":"fitness","category_name":"Sports & Fitness","tool_name":"calculate_running_pace","featured_mcp_tool":true,"description":"Computes running pace in min/km and min/mile and speed in km/h and mph from a distance and elapsed time, and projects the finish time for 5 km, 10 km, half marathon and marathon at that constant pace.","use_when":"You know a distance and the time it took (or a target time) and need the pace, the equivalent speed, or the time that pace gives over standard race distances.","do_not_use_when":"You want a realistic prediction of a longer race from a shorter one (pace slows with distance; use race-time-predictor), or you only need to convert between pace and speed units (use pace-converter).","inputs":[{"name":"distance","label":"Distance","type":"number","required":true,"max":5000,"exclusive_min":0,"description":"Distance covered, in the unit given by distance_unit.","example":10},{"name":"distance_unit","label":"Distance unit","type":"enum","required":false,"default":"km","values":[{"value":"km","label":"Kilometres","aliases":["kilometers","kilometres","k"]},{"value":"mi","label":"Miles","aliases":["mile","miles"]}],"description":"Unit of the distance input.","example":"km"},{"name":"time","label":"Time","type":"string","required":true,"description":"Elapsed time as h:mm:ss (1:45:00), mm:ss (50:00) or plain minutes (50).","example":"50:00"}],"outputs":[{"name":"pace_min_per_km","label":"Pace per km","type":"string","unit":"min:sec/km","decimals":4,"description":"Minutes and seconds per kilometre."},{"name":"pace_min_per_mile","label":"Pace per mile","type":"string","unit":"min:sec/mi","decimals":4,"description":"Minutes and seconds per mile."},{"name":"pace_seconds_per_km","label":"Pace per km (seconds)","type":"number","unit":"s/km","decimals":1,"description":"Same pace as a plain number of seconds per kilometre."},{"name":"speed_kmh","label":"Speed","type":"number","unit":"km/h","decimals":2,"description":"Average speed in kilometres per hour."},{"name":"speed_mph","label":"Speed","type":"number","unit":"mph","decimals":2,"description":"Average speed in miles per hour."},{"name":"distance_km","label":"Distance","type":"number","unit":"km","decimals":4,"description":"Input distance converted to kilometres."},{"name":"time_5k","label":"5 km at this pace","type":"string","unit":"h:mm:ss","decimals":4,"description":"Time to run 5 km at exactly this pace."},{"name":"time_10k","label":"10 km at this pace","type":"string","unit":"h:mm:ss","decimals":4,"description":"Time to run 10 km at exactly this pace."},{"name":"time_half_marathon","label":"Half marathon at this pace","type":"string","unit":"h:mm:ss","decimals":4,"description":"Time for 21.0975 km at exactly this pace."},{"name":"time_marathon","label":"Marathon at this pace","type":"string","unit":"h:mm:ss","decimals":4,"description":"Time for 42.195 km at exactly this pace."}],"input_schema":{"type":"object","properties":{"distance":{"description":"Distance covered, in the unit given by distance_unit.","type":"number","maximum":5000,"exclusiveMinimum":0,"examples":[10]},"distance_unit":{"description":"Unit of the distance input.","type":"string","enum":["km","mi"],"default":"km","examples":["km"]},"time":{"description":"Elapsed time as h:mm:ss (1:45:00), mm:ss (50:00) or plain minutes (50).","type":"string","examples":["50:00"]}},"additionalProperties":false,"required":["distance","time"]},"output_schema":{"type":"object","properties":{"pace_min_per_km":{"description":"Minutes and seconds per kilometre. Unit: min:sec/km.","type":"string","x-unit":"min:sec/km"},"pace_min_per_mile":{"description":"Minutes and seconds per mile. Unit: min:sec/mi.","type":"string","x-unit":"min:sec/mi"},"pace_seconds_per_km":{"description":"Same pace as a plain number of seconds per kilometre. Unit: s/km.","type":"number","x-unit":"s/km"},"speed_kmh":{"description":"Average speed in kilometres per hour. Unit: km/h.","type":"number","x-unit":"km/h"},"speed_mph":{"description":"Average speed in miles per hour. Unit: mph.","type":"number","x-unit":"mph"},"distance_km":{"description":"Input distance converted to kilometres. Unit: km.","type":"number","x-unit":"km"},"time_5k":{"description":"Time to run 5 km at exactly this pace. Unit: h:mm:ss.","type":"string","x-unit":"h:mm:ss"},"time_10k":{"description":"Time to run 10 km at exactly this pace. Unit: h:mm:ss.","type":"string","x-unit":"h:mm:ss"},"time_half_marathon":{"description":"Time for 21.0975 km at exactly this pace. Unit: h:mm:ss.","type":"string","x-unit":"h:mm:ss"},"time_marathon":{"description":"Time for 42.195 km at exactly this pace. Unit: h:mm:ss.","type":"string","x-unit":"h:mm:ss"}}},"formula":"pace_s_per_km = time_seconds / distance_km; pace_s_per_mile = pace_s_per_km × 1.609344; speed_kmh = 3600 / pace_s_per_km; speed_mph = speed_kmh / 1.609344; time(D) = pace_s_per_km × D for D = 5, 10, 21.0975, 42.195 km","method":"Splits assume a perfectly even pace; they are not race predictions. Distances follow World Athletics definitions (half marathon 21.0975 km, marathon 42.195 km).","sources":[{"name":"World Athletics – Book of Rules (Technical Rules: road race distances 5 km, 10 km, half marathon 21.0975 km, marathon 42.195 km)","url":"https://worldathletics.org/about-iaaf/documents/book-of-rules","type":"standard","retrieved_at":"2026-09-23"},{"name":"NIST Special Publication 811 – Guide for the Use of the SI (Appendix B: 1 mile = 1609.344 m, 1 yard = 0.9144 m)","url":"https://www.nist.gov/pml/special-publication-811","type":"standard","retrieved_at":"2026-09-23"}],"freshness":{"type":"static","max_age_seconds":null,"note":"Deterministic formula with fixed constants; results never go stale. Inputs supplied by the caller determine the output."},"examples":[{"name":"10 km in 50:00","inputs":{"distance":10,"distance_unit":"km","time":"50:00"},"expected":{"pace_min_per_km":"5:00","pace_min_per_mile":"8:03","pace_seconds_per_km":300,"speed_kmh":12,"speed_mph":7.46,"time_5k":"0:25:00","time_half_marathon":"1:45:29","time_marathon":"3:30:59"},"url":"https://tttkmbb.com/api/v1/calculate/running-pace?distance=10&distance_unit=km&time=50%3A00"},{"name":"5 miles in 45:00","inputs":{"distance":5,"distance_unit":"mi","time":"45:00"},"expected":{"pace_min_per_mile":"9:00","pace_min_per_km":"5:36","speed_mph":6.67,"speed_kmh":10.73,"time_10k":"0:55:55"},"url":"https://tttkmbb.com/api/v1/calculate/running-pace?distance=5&distance_unit=mi&time=45%3A00"}],"faq":[{"q":"How do I enter the time?","a":"As h:mm:ss (1:45:00), mm:ss (50:00) or a plain number of minutes (50 or 50.5)."},{"q":"Why is my marathon split faster than what I could actually run?","a":"The splits hold the pace constant. Real performance slows with distance; race-time-predictor applies Riegel's fatigue exponent to model that."}],"tags":["running pace","pace calculator","min per km","min per mile","race splits","running speed"],"related":[{"calculator_id":"race-time-predictor","reason":"Predict realistic finish times for other distances instead of constant-pace splits."},{"calculator_id":"pace-converter","reason":"Convert between min/km, min/mile, km/h and mph directly."},{"calculator_id":"heart-rate-zones","reason":"Pair pace targets with heart-rate training zones."}],"links":{"html":"https://tttkmbb.com/fitness/running-pace","markdown":"https://tttkmbb.com/fitness/running-pace.md","json":"https://tttkmbb.com/fitness/running-pace.json","api":"https://tttkmbb.com/api/v1/calculate/running-pace","schema":"https://tttkmbb.com/api/v1/calculators/running-pace","openapi":"https://tttkmbb.com/openapi.json","mcp":"https://tttkmbb.com/mcp"},"version":"v1","updated_at":"2026-09-23"},"timestamp":"2026-09-23T23:30:47Z","next_actions":[{"tool":"calculate_running_pace","calculator_id":"running-pace","reason":"Run Running Pace Calculator with the inputs above."}],"links":{"markdown":"https://tttkmbb.com/fitness/running-pace.md"}}