# Pace Converter

> Converts a running pace or speed given in any one of min/km, min/mile, km/h or mph into all four units, plus seconds per km/mile and metres per second.

- Calculator id: `pace-converter` · Category: Sports & Fitness (`fitness`) · Tool name: `convert_running_pace`
- Canonical page: https://tttkmbb.com/fitness/pace-converter · This document: https://tttkmbb.com/fitness/pace-converter.md · JSON definition: https://tttkmbb.com/fitness/pace-converter.json

## Purpose

Converts a running pace or speed given in any one of min/km, min/mile, km/h or mph into all four units, plus seconds per km/mile and metres per second.

**Use when:** You need to translate a treadmill speed into a pace, a min/mile pace into min/km, or any other pace/speed unit conversion.

**Do not use when:** You have a distance and time rather than a pace (use running-pace) or a swim time (use swim-pace).

## Input

| Parameter | Type | Unit | Required | Description |
| --- | --- | --- | --- | --- |
| `pace_min_per_km` | string |  | optional | Pace as mm:ss per kilometre (e.g. 5:00) or decimal minutes (5.5). Give exactly one of the four inputs; if several are given, this one takes precedence. |
| `pace_min_per_mile` | string |  | optional | Pace as mm:ss per mile (e.g. 8:03) or decimal minutes. |
| `speed_kmh` | number | km/h | optional | Speed in kilometres per hour (e.g. treadmill display). (> 0, max 100) |
| `speed_mph` | number | mph | optional | Speed in miles per hour. (> 0, max 60) |

## Output

| Field | Type | Unit | Description |
| --- | --- | --- | --- |
| `pace_min_per_km` | string | min:sec/km | Minutes and seconds per kilometre. |
| `pace_min_per_mile` | string | min:sec/mi | Minutes and seconds per mile. |
| `speed_kmh` | number | km/h | Kilometres per hour. |
| `speed_mph` | number | mph | Miles per hour. |
| `pace_seconds_per_km` | number | s/km | Pace as seconds per kilometre. |
| `pace_seconds_per_mile` | number | s/mi | Pace as seconds per mile. |
| `speed_m_per_s` | number | m/s | Metres per second. |
| `source_input` | string |  | Which input was used as the source value. |

## Formula

`pace_s_per_km = 3600 / speed_kmh; pace_s_per_mile = pace_s_per_km × 1.609344; speed_mph = speed_kmh / 1.609344; speed_m_per_s = speed_kmh / 3.6 (1 mile = 1609.344 m)`

## Data Sources

- NIST Special Publication 811 – Guide for the Use of the SI (Appendix B: 1 mile = 1609.344 m, 1 yard = 0.9144 m) — https://www.nist.gov/pml/special-publication-811 (standard, retrieved 2026-09-23)

Data freshness: `static`. Deterministic formula with fixed constants; results never go stale. Inputs supplied by the caller determine the output.

## API

- `GET https://tttkmbb.com/api/v1/calculate/pace-converter?`
- `POST https://tttkmbb.com/api/v1/calculate/pace-converter` with JSON body `{"inputs": {…}}`
- Response: unified envelope (`success`, `request`, `result.values`, `result.units`, `sources`, `freshness`, `timestamp`, `next_actions`, `links`); see https://tttkmbb.com/docs/response-format.md
- Schema: https://tttkmbb.com/api/v1/calculators/pace-converter · OpenAPI operationId `convert_running_pace` in https://tttkmbb.com/openapi.json
- Authentication: none. Rate limit: fair use, see https://tttkmbb.com/docs/rate-limits.md.

## MCP

- Server: `https://tttkmbb.com/mcp` (Streamable HTTP, JSON-RPC 2.0, no auth)
- Tool:  `run_calculator` with `{"calculator_id": "pace-converter", "inputs": {…}}`

## Example

- 5:00 min/km: inputs `{"pace_min_per_km":"5:00"}` → `{"pace_min_per_mile":"8:03","speed_kmh":12,"speed_mph":7.46,"pace_seconds_per_km":300,"pace_seconds_per_mile":482.8,"speed_m_per_s":3.333,"source_input":"pace_min_per_km"}`
- 6 mph treadmill: inputs `{"speed_mph":6}` → `{"speed_kmh":9.66,"pace_min_per_mile":"10:00","pace_min_per_km":"6:13","pace_seconds_per_km":372.8}`

```
GET https://tttkmbb.com/api/v1/calculate/pace-converter?pace_min_per_km=5%3A00
```

## Limitations

You have a distance and time rather than a pace (use running-pace) or a swim time (use swim-pace). All values are computed from the formula above; no measurement or live data is involved.

## FAQ

**What if I give more than one input?**

The first available in the order pace_min_per_km, pace_min_per_mile, speed_kmh, speed_mph is used and the rest are ignored; a note says which one.

**How do I enter a pace like 7 minutes 30 seconds?**

As 7:30 or as decimal minutes 7.5; both give the same result.

## Related

- [Running Pace Calculator](https://tttkmbb.com/fitness/running-pace.md) — Pace from a distance and time, with race splits.
- [Swim Pace Calculator](https://tttkmbb.com/fitness/swim-pace.md) — Pace per 100 m for swimming.
- [Speed Converter](https://tttkmbb.com/conversion/speed.md) — General speed unit conversions.