# Feet per second to Miles per hour (ft/s to mph)

> Convert feet per second to miles per hour: 1 ft/s = 0.681818 mph. Exact conversion factor, formula, 22-row table and worked examples, with JSON API and MCP access.

- Page id: `feet-per-second-to-mph` · Quantity: Speed (`speed`, base unit m/s) · Tool: `convert_units`
- Canonical page: https://tttkmbb.com/conversion/feet-per-second-to-mph · This document: https://tttkmbb.com/conversion/feet-per-second-to-mph.md · JSON: https://tttkmbb.com/conversion/feet-per-second-to-mph.json (add `?value=` for a result)

## Formula

- `1 ft/s = 0.681818 mph`
- `miles per hour = feet per second × 0.6818181818`
- Reverse: `feet per second = miles per hour × 1.466666667`

The factor follows from the SI definitions of both units (NIST SP 811); values below are rounded to 6 significant figures, the API returns up to 12.

## Worked examples

- 5 ft/s = 3.40909 mph
- 12.5 ft/s = 8.52273 mph
- 100 ft/s = 68.1818 mph

## Conversion table

| Feet per second (ft/s) | Miles per hour (mph) |
| --- | --- |
| 1 | 0.681818 |
| 2 | 1.36364 |
| 3 | 2.04545 |
| 4 | 2.72727 |
| 5 | 3.40909 |
| 6 | 4.09091 |
| 7 | 4.77273 |
| 8 | 5.45455 |
| 9 | 6.13636 |
| 10 | 6.81818 |
| 15 | 10.2273 |
| 20 | 13.6364 |
| 25 | 17.0455 |
| 30 | 20.4545 |
| 40 | 27.2727 |
| 50 | 34.0909 |
| 75 | 51.1364 |
| 100 | 68.1818 |
| 200 | 136.364 |
| 250 | 170.455 |
| 500 | 340.909 |
| 1000 | 681.818 |

## API

- `GET https://tttkmbb.com/api/v1/convert?value=5&from_unit=ft%2Fs&to_unit=mph` → unified JSON envelope with `result.values.result`, `formula`, `factor`, `sources`, `freshness`
- MCP: server `https://tttkmbb.com/mcp`, tool `convert_units` with `{"value":5,"from_unit":"ft/s","to_unit":"mph"}`
- All speed units: https://tttkmbb.com/api/v1/units?quantity=speed · full converter: [Speed Converter](https://tttkmbb.com/conversion/speed.md)
- Authentication: none. Freshness: `static` (fixed conversion factors).

## FAQ

**How many miles per hour are in one foot per second?**

1 ft/s = 0.681818 mph. The factor comes from the SI definitions of both units (NIST SP 811 / BIPM), so it is exact or correct to at least 10 significant figures.

**What is the formula to convert feet per second to miles per hour?**

Multiply the value in feet per second by 0.6818181818: miles per hour = feet per second × 0.6818181818. For example, 5 ft/s = 3.40909 mph.

**How do I convert miles per hour back to feet per second?**

Multiply by the inverse factor 1.466666667 (feet per second = miles per hour × 1.466666667), or use the miles per hour-to-feet per second page.

## Related conversions

- [Miles per hour to feet per second](https://tttkmbb.com/conversion/mph-to-feet-per-second.md) (reverse)
- [Kilometers per hour to Miles per hour](https://tttkmbb.com/conversion/kmh-to-mph.md)
- [Miles per hour to Kilometers per hour](https://tttkmbb.com/conversion/mph-to-kmh.md)
- [Meters per second to Kilometers per hour](https://tttkmbb.com/conversion/meters-per-second-to-kmh.md)
- [Kilometers per hour to Meters per second](https://tttkmbb.com/conversion/kmh-to-meters-per-second.md)
- [Meters per second to Miles per hour](https://tttkmbb.com/conversion/meters-per-second-to-mph.md)
- [Miles per hour to Meters per second](https://tttkmbb.com/conversion/mph-to-meters-per-second.md)
- [Knots to Kilometers per hour](https://tttkmbb.com/conversion/knots-to-kmh.md)
- [Kilometers per hour to Knots](https://tttkmbb.com/conversion/kmh-to-knots.md)

## Data Sources

- NIST Special Publication 811 – Guide for the Use of the International System of Units (SI), Appendix B conversion factors — https://www.nist.gov/pml/special-publication-811 (standard, retrieved 2026-09-24)
- BIPM – The International System of Units (SI Brochure, 9th edition) — https://www.bipm.org/en/publications/si-brochure (standard, retrieved 2026-09-24)
- Wikipedia – Conversion of units — https://en.wikipedia.org/wiki/Conversion_of_units (reference, retrieved 2026-09-24)