Acceleration Converter

Most acceleration converters make you pick a "from" unit AND a "to" unit before they'll tell you a single thing, which is backwards for what people actually do. You're usually staring at one number, a g-force off a spec sheet, a 0-to-60 time, an old gravimeter reading, and you haven't even decided yet which unit you want it in. So this one throws out the "to" picker. Type your value, tell it what unit that value is already in, and all seven units fill in at once, live: m/s², ft/s², g, gal, in/s², km/h/s, and mph/s. Copy whichever row you need, or grab a link that reopens the page with your exact number already converted. It runs entirely in your browser, nothing you type is uploaded, and once the page has loaded it keeps working with no connection at all.

Acceleration is awkward to convert because it's a rate of a rate. Speed is how fast you're going. Acceleration is how fast that speed is changing, so the units read "meters per second, per second," which is where m/s² comes from. That extra layer is why a physics set says m/s², a car magazine says g, a European gravimeter reads out in gal, and a drag strip talks in mph/s, all different labels for the same quantity.

1. Type your number in the Value box. Decimals are fine, and if it gets very large or very small the output switches to scientific notation so you're never reading a wall of zeros.
2. Set the From dropdown to the unit your number is already in. That's the only unit you choose.
3. Read the table. Each row is your value expressed in that unit, and the row matching your From unit is shaded, so you always know which one is the input and which are the conversions.
4. Hit copy on any row to drop that value straight onto your clipboard.
5. Need to hand the exact conversion to someone? Copy shareable link builds a URL with your number and unit baked in. Open that link and the page comes up already filled out.

Every factor is the standard one. One g is exactly 9.80665 m/s², one foot per second² is exactly 0.3048, one gal is 0.01. Values carry enough significant figures to stay honest for engineering or homework, and you round to whatever your task actually needs.

Of the seven, g is the one that pulls people to a converter, and it's the one that gets misread the most. One g is the acceleration Earth's gravity gives a falling object near the surface, fixed by international agreement at exactly 9.80665 m/s². Drop something (ignore the air) and each second its downward speed grows by about 9.8 m/s. That's 1 g.

When a pilot "pulls 5 g" in a hard turn, nobody's falling. The g is just being used as a yardstick for any acceleration, gravity or not. 5 g means five times 9.80665, roughly 49 m/s². It caught on because humans have a gut feel for one g, it's the pull we live in every second we're awake, so multiples of it map onto something you can feel. 2 g and you feel twice your weight. Push past 4 to 6 g and blood stops reaching the brain, which is why fighter pilots wear pressurized suits. That felt-ness is exactly why aerospace, motorsport, and roller-coaster specs all quote g instead of raw m/s².

Sitting still in your chair, are you "at 1 g"? Your acceleration is zero, you aren't going anywhere. But you feel 1 g, because the seat pushes up to hold you against gravity, and that's the force an accelerometer measures. It reports the push needed to keep an object in place, not motion through space. A phone lying flat on a table reads about 9.8 m/s² on its vertical axis, not zero. So when you convert a g reading here, you're converting that acceleration magnitude, and the tool doesn't care whether it came from gravity, a corner, or a rocket. Quick sanity check: 2 g is 19.6133 m/s². If your other number disagrees, one of you is wrong.

km/h/s and mph/s look bizarre until you decode them, and then they're the friendliest units on the list. km/h/s means "kilometers per hour, added every second." mph/s means "miles per hour, added every second." They describe acceleration the way a driver feels it, how fast the speedometer needle climbs.

Take a car doing 0 to 60 mph in 6 seconds. Its average acceleration is 60 ÷ 6 = 10 mph/s, ten miles per hour gained each second. That's a number your gut understands. The same thing in m/s² is about 4.47, correct but meaningless to your body. That's the whole appeal of these two units.

The conversion is where people slip. To turn mph/s into m/s² you only fix the speed part. The "per second" of the acceleration is already in seconds, leave it alone. One mile per hour is 0.44704 m/s, so 1 mph/s = 0.44704 m/s². Same for km/h/s: one km/h is 0.27778 m/s, so 1 km/h/s is about 0.27778 m/s². The classic mistake is converting the hours-to-seconds a second time, effectively squaring it, and the answer comes out wildly off. The tool applies it once, correctly, and doing it by hand is the one place to slow down.

The other five units are less dramatic. m/s² is the SI base and the safe default for anything scientific. ft/s² and in/s² are the imperial physics units, only the length differs so the factors are just 0.3048 and 0.0254. And gal is the tiny geophysics unit, a hundredth of a m/s², built for measuring how Earth's gravity shifts from place to place. You'll rarely touch those last three unless the field hands them to you, which is exactly why having all seven on screen beats hunting for the right factor.