In machining, surface speed represents the speed the cutter's outside edge travels. Use surface speed and the the cutter's size to calculate the rotation speed in revolutions per minute (RPM).

## Step 1

Convert surface speed to feet per minute. To convert from meters per second, multiply by 196.85. For instance, if the surface speed is 2 m/s:

2 * 196.85 = 393.7

## Step 2

Multiply your answer by 4.

393.7 * 4 = 1,574.8

## Step 3

Convert your cutter's diameter to feet. For instance, if your cutter measures 6in across:

6 / 12 = 0.5 ft

## Step 4

Divide your answer from Step 2 by you cutter diameter in feet.

1,574.8 / 0.5 = 3,149.6

This is approximately 3,150 RPM.

### Tip

"Surface speed" is also known as "cutting speed."

If you don't have a calculator handy, use your computer's calculator or a Google search bar.