A quick guide to converting feet per second to miles per hour or meters per second

Most airsoft replicas are measured in the feet per second (fps) that they propel a projectile, but a lot of people may not know exactly how fast that really is. We are pretty used to being in cars moving at miles per hour, so this article will give you a quick and dirty way to get rough conversions from one to the other, along with a “gustimate” on meters per second as well.

For some the math might be a little hairy, so a table of common fps numbers are listed below and you can guess the in between numbers as needed or dump the conversion into a search engine to get an exact number.

For converting MPH to FPS, take half the number and add it in. For example, 200 mph plus half, 100 mph gives you 300 fps. This is not quite exact, but is close. Just a bit under half (40 to 45%ish) gives you a guesstimate number of 90 meters per second (this is very not exact but is easy to remember on the fly in the field).

Feet per second to MPH is a little trickier, being about 2/3. So if you can do the math in your head, if you have fps, multiply it by 0.66 to get your MPH numbers. The same sort of iffy math works for meters per second too... just multiply by .3 to get a pretty close approximation.

Meters per second are where things get useful; some springs are rated as “Mxxx” (example M120 springs). This is how many meters per second the given spring would push a .20 gram bb from an otherwise stock TM replica. Multiplying the mps by .33 will give you a ball park fps, but if you are aiming for a specific fps do the real math and take into consideration other factors like your cylinder, piston, barrel bore and any other mods you may have made to the power system. Of course, do your research and educate yourself on any possible mods you might want to undertake well before you attempt them!

That about covers our quick and dirty conversion formulas, and the chart below can be used as a reference if needed. We may post a more extensive chart for use here in the future in 5 fps increments that can be printed out and kept in your gear case.

The chart below is rounded to the nearest whole number, with the exception of 330 fps, which is exactly 225 mph.

Feet/second Miles/hour Meters/second

100 68 30
150 102 46
200 136 61
250 170 76
300 205 91
330 225* 101
350 239 107
400 273 122

Hmm. Post posting it seems the table did not post in quite as planned, so you will have to eyeball it and see if you can figure it out until we re-update with the extended table. Sorry guys!