What speed of sound is used for the conversion?

The converter uses 1,116 ft/s (approximately 761 mph or 340 m/s), which is the International Standard Atmosphere (ISA) speed of sound at sea level and 15 °C (59 °F). Speed of sound varies with altitude and temperature; this value is the widely accepted standard for sea-level calculations.

What is Mach 1 in feet per second?

Mach 1 equals exactly 1,116 ft/s under standard sea-level ISA conditions. This is approximately 340 m/s, 1,235 km/h, or 761 mph.

What are the speed classifications shown?

Subsonic: below Mach 0.8. Transonic: Mach 0.8–1.2. Supersonic: Mach 1.2–5. Hypersonic: Mach 5 and above. These are standard aerospace engineering ranges.

Does altitude affect the Mach number conversion?

Yes — at higher altitudes the air is colder, so the speed of sound decreases. This tool uses the sea-level standard (1,116 ft/s). For high-altitude calculations, the actual Mach number will be higher than what this tool shows for the same ft/s value.

How fast is Mach 2 in feet per second?

Mach 2 is 2 × 1,116 = 2,232 ft/s at standard sea-level conditions, which is roughly 1,522 mph or 2,450 km/h.

Feet per Second to Mach Converter

Name: Feet per Second to Mach Converter
Availability: InStock
Author: Nham Vu

Convert feet per second (ft/s) to Mach number using the standard speed of sound at sea level (1,116 ft/s).

Speed Input

Speed (feet per second)

ft/s

Based on ISA sea-level speed of sound: 1,116 ft/s (≈ 340 m/s, 761 mph).

Result

Enter a value on the left to see the result.

Quick Reference — Common Speeds

Object / Vehicle	ft/s	Mach

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Summary

Convert feet per second (ft/s) to Mach number using the standard speed of sound at sea level (1,116 ft/s).

How it works

Enter a speed value in feet per second (ft/s) in the input field.
The tool divides your value by 1,116 ft/s (standard speed of sound at sea level, ISA conditions).
The Mach number is displayed instantly along with the speed in km/h, mph, and m/s.
A classification badge shows whether the speed is subsonic, transonic, supersonic, or hypersonic.
Use the swap button to reverse the conversion from Mach to ft/s.

Use cases

Calculating the Mach number of an aircraft or projectile given its speed in ft/s.
Converting wind tunnel test speeds from ft/s to Mach for reporting.
Checking whether a vehicle crosses the sound barrier (Mach 1).
Educational exercises involving supersonic and hypersonic speed ranges.
Comparing the speed of bullets, rockets, or jets against the speed of sound.
Aerospace engineering coursework and reference lookups.

Frequently Asked Questions

Last updated: 2026-07-23 · Reviewed by Nham Vu