To convert ft/s to mph, multiply by 15/22 (≈ 0.681818). The factor is exact: 1 mile = 5,280 feet; 1 hour = 3,600 seconds. So 1 ft/s = 3,600 ÷ 5,280 = 15/22 mph. For the reverse, multiply mph by 22/15 (≈ 1.46667).
- Exact factor: 1 ft/s = 15/22 mph = 0.681818... mph (a repeating decimal, not a rounding).
- Notable benchmark: 60 mph = 88 ft/s exactly — a well-known identity in US engineering.
- Speed of sound at sea level (15°C) ≈ 1,125 ft/s = 767 mph.
- ft/s is the standard unit for muzzle velocity in US ballistics specifications (SAAMI).
How to Use This Converter
Enter a value in the ft/s field and the mph equivalent appears immediately. You can also type in the mph field to reverse the conversion. There's no submit button — results update as you type. Both fields stay in sync at all times.
How Do You Convert ft/s to mph?
Multiply feet per second by 15/22. Both the numerator and denominator come from exact unit definitions: one mile = 5,280 feet (by statute), one hour = 3,600 seconds. So 1 ft/s = 3,600 seconds/hour ÷ 5,280 feet/mile = 3600/5280 = 15/22 mph. This is a repeating decimal (0.681818…) but the fraction 15/22 is exact. The US National Institute of Standards and Technology (NIST) publishes this as an exact conversion.
$$\text{mph} = \text{ft/s} \times \frac{3600}{5280} = \text{ft/s} \times \frac{15}{22} \approx \text{ft/s} \times 0.681818$$
Worked examples: 50 ft/s = 34.09 mph. 88 ft/s = 60 mph (exact). 1,125 ft/s = 767 mph (speed of sound at sea level).
How Do You Convert mph to ft/s?
Multiply mph by 22/15 (≈ 1.46667). This is the exact inverse of the 15/22 ratio. The result 22/15 is also a repeating decimal (1.46666…) but the fraction is exact. For a quick mental estimate: multiply mph by 1.5 (about 2.3% high) — for 60 mph that gives 90 ft/s vs the exact 88 ft/s. For the full multi-unit converter covering m/s, km/h, and knots, use the speed converter hub.
$$\text{ft/s} = \text{mph} \times \frac{22}{15} \approx \text{mph} \times 1.46667$$
Worked examples: 30 mph = 44 ft/s. 60 mph = 88 ft/s (exact). 100 mph = 146.67 ft/s.
ft/s to mph Reference Table
Key speed values with exact ft/s to mph conversions and real-world contexts. The factor 15/22 is exact; displayed values are rounded to 2 decimal places for readability.
| ft/s | mph | m/s | Context |
|---|---|---|---|
| 5 ft/s | 3.41 mph | 1.52 m/s | Walking pace |
| 10 ft/s | 6.82 mph | 3.05 m/s | Jogging |
| 15 ft/s | 10.23 mph | 4.57 m/s | Fast cycling |
| 40 ft/s | 27.27 mph | 12.19 m/s | Sprinting athlete |
| 44 ft/s | 30 mph | 13.41 m/s | Urban speed limit (US) |
| 66 ft/s | 45 mph | 20.12 m/s | Rural road (US) |
| 88 ft/s | 60 mph | 26.82 m/s | Highway (US) — exact 88 ft/s |
| 95.33 ft/s | 65 mph | 29.06 m/s | Interstate (many US states) |
| 102.67 ft/s | 70 mph | 31.29 m/s | Highway / motorway |
| 146.67 ft/s | 100 mph | 44.70 m/s | Performance driving |
| 1,125 ft/s | 767.0 mph | 342.9 m/s | Speed of sound (approx., sea level) |
| 2,800 ft/s | 1,909 mph | 853.4 m/s | Rifle muzzle velocity (typical) |
When Do You Need to Convert ft/s to mph?
Feet per second is used in US engineering, ballistics, and athletics alongside miles per hour for road speeds. The two units coexist in American technical practice — a firearms specification might give muzzle velocity in ft/s while a related wind speed is reported in mph. According to NIST (2023), ft/s remains a common unit in US legal and engineering contexts where the foot is the standard length unit.
Common situations:
- Ballistics — SAAMI and US ammunition manufacturers publish muzzle velocities in ft/s. Converting to mph gives context: a 2,900 ft/s rifle round travels at 1,977 mph (about 2.6× the speed of sound).
- Athletics and biomechanics — US sports science often uses ft/s for sprint speed and throwing velocity; coaches convert to mph for media reporting.
- Structural engineering — wind load calculations in US codes (ASCE 7) reference wind speed in mph; structural dynamic analysis uses ft/s.
- Aviation (US) — approach and stall speeds are in knots in modern aviation, but older US documents and some military specs use ft/s alongside mph.
Frequently Asked Questions
How do you convert ft/s to mph?
Multiply ft/s by 15/22 (≈ 0.681818). One mile = 5,280 feet; one hour = 3,600 seconds. So 1 ft/s = 3,600/5,280 = 15/22 mph. This fraction is exact. Example: 88 ft/s × 15/22 = 60 mph exactly.
How many ft/s is 60 mph?
60 mph = 88 ft/s exactly. Multiply mph by 22/15 = 1.4̄6̄ to get ft/s. The result 88 is exact because 60 × 22 = 1,320 and 1,320 ÷ 15 = 88. This is one of the best-known exact unit conversion benchmarks in US engineering.
How fast is 1,000 ft/s in mph?
1,000 ft/s = 681.82 mph (1,097.3 km/h, about Mach 0.89 at sea level). Subsonic jet aircraft at cruise typically fly around 490 knots (564 mph / 826 ft/s). A 1,000 ft/s wind would be a hypersonic event — significantly faster than any naturally occurring surface wind.
Why is ft/s used in ballistics?
US ballistics and ammunition standards (SAAMI) use feet as the primary length unit, so muzzle velocity in ft/s is the natural choice. Internationally, m/s is used. Many ballistic tables give both: a 9mm handgun cartridge might be rated at 1,150 ft/s (351 m/s). Converting between them uses the exact factor 0.3048 m per foot.
How fast is the speed of sound in ft/s?
At sea level and 15°C, the speed of sound is approximately 1,125 ft/s (767 mph, 340.3 m/s). US aviation and ballistics sources commonly cite 1,116 ft/s at standard sea-level conditions (ICAO standard atmosphere: 15°C, 101.325 kPa). The value decreases with altitude as air temperature drops.