In case you've never gotten along with millimeters, or in case you need to do some conversions and never got along with algebra, this page contains easy conversions back and forth between inches and millimeters.

### Sections on this page:

**Easy estimates,**without a calculator

Inch-to-Millimeter

Millimeter-to-Inch- How to make
**Exact Conversions,**with a calculator

Inch-to-Millimeter

Millimeter-to-Inch - Other miscellaneous conversion units

#### If you have inches, and want to know how many millimeters:

**Step one:**Convert any inch fractions to decimals.*Example:*1/4 inch = 1 divided by 4 = 0.25 inch*Example:*1/16 inch = 1 divided by 16 = 0.0625 inch- For amounts over an inch, you want to first convert the fractional part, then add the whole inches part:

*Example:*2-1/4 inch = 1 divided by 4, then plus 2 = 2.25 inch*Example:*1-5/8 inch = 5 divided by 8, then plus 1 = 1.625 inch**Step two:**Multiply that decimal by 25.4

For each of the above examples, the complete steps would be:*1/4 inch*= 1 divided by 4, x 25.4 =*6.35mm (6mm)**1/16 inch*= 1 divided by 16, x 25.4 =*1.5875 (1.6mm)**2-1/4 inch*= 1 divided by 4, plus 2, x 25.4 =*57.15 (57mm)**1-5/8 inch*= 5 divided by 8, plus 1, x 25.4 =*41.275 (41mm)*

#### If you have millimeters (or centimeters), and you want inches:

**Step one:**Divide your millimeter amount by 25.4

(or divide your centimeter amount by 2.54)*Example 1:*2mm divided by 25.4 = .07874 inches*Example 2:*6mm divided by 25.4 = .2362 inches*Example 3:*30mm divided by 25.4 = 1.1811 inches*Example 4:*4cm divided by 2.54 = 1.5748 inches

*Example 2*above, you know that a 6mm bead = .2362 inches.

So, 20 inches (per necklace) divided by .2362 inches (per bead) = 84.67 beads per necklace.

Since you probably need to reserve a bit of space for your bead tips and a clasp, I would round down to 80 beads. Number of beads per strand

*chart*

If, however, you want fractions of an inch (1/16, 1/4, 1/2), rather than a decimal, try this:

**Step two:**Converting your decimal to a useable fraction:*I prefer to round to the nearest 1/16 of an inch. To round to the nearest 1/16 of an inch, multiply your decimal by 16. The resulting number is how many 1/16's of an inch you have.*Using the numbers from Step 1 above:

*.07874*times 16 = 1.26, which rounds to 1, so about 1/16 inch.*.2362*times 16 = 3.779, which rounds to 4, so about 4/16. 4/16 = 1/4 inch- For amounts over an inch, it is easiest to remove the whole inches, and add them back in after you convert the portion after the decimal point:

*1.1811*Removing the 1 gives you .1811 times 16 = 2.9, which rounds to 3, so about 3/16 inch... don't forget to add the 1 back on, so this is really 1-3/16 inch.*1.5748*Removing the 1 gives you .5748 times 16 = 9.1968, which rounds to 9, so about 9/16 inch... don't forget to add the 1 back on, so this is really 1-9/16 inch.

Using the numbers from step 1, that I also used in step 2, you would get...

*.07874*times 4 = .315, which rounds to 0, so you get 0/4 of an inch (not a very useful number!)

*.2362*times 4 = .9448, which rounds to 1, so you get 1/4 of an inch (which happens to be accurate)

- inches to millimeters, multiply by 25.4
- inches to centimeters, multiply by 2.54
- millimeters to inches, divide by 25.4
- centimeters to inches, divide by 2.54

- meters to feet, multiply by 3.28
- feet to meters, divide by 3.28

- millimeters to centimeters, divide by 10
- centimeters to meters, divide by 100