To convert picas to millimeters, multiply by 4.233333333. That factor is the whole relationship: both units measure length, so the conversion is a proportion with no offset and no substance-specific constant.
One thousandth of a metre — the finest gradation on a standard ruler. Twelve points, or 1/6 inch — the column-width unit of print layout.
The mil and the millimetre are not the same thing and are out by a factor of about forty. A mil is one thousandth of an inch — 0.0254 mm — and a spec sheet that quotes film thickness in mils means the small unit. British drawings write the same size as "thou". Below the calculator there is a step table for the values people look up most, and a second table putting real length figures into millimeters so the number you get has something to be compared against.
The formula
picas- The amount you are converting, in picas
4.23333333333- The exact number of millimeters in one pica
millimeters- The converted result
How it works, step by step
- Enter the value in picas.
- It is multiplied by 4.23333333333, the exact factor between the two units.
- The answer is shown in millimeters, with the reverse conversion beneath it.
- Check the reference table if you want a figure of comparable size.
Worked examples
An Olympic pool: 1.18e+04 pica in millimeters
An Olympic pool comes to about 1.18e+04 pica. Multiplying by the factor: 1.18e+04 × 4.23333 = 49,953.3 mm. Dividing the answer back by 4.23333 returns the figure you started with, which is the quickest way to check you have the factor the right way up.
A credit card’s long edge: 20.2 pica in millimeters
At 20.2 pica (a credit card’s long edge), the same quantity in millimeters is 20.2 × 4.23333 = 85.5133 mm. One pica is 4.23333 millimeters, so the numbers grow as expected.
How to read your score
Frequently asked questions
How many millimeters are in one pica?
Exactly 4.23333333333. Every figure on this page is that one number multiplied by your input, so the only rounding is at the display step.
What is the formula to convert picas to millimeters?
millimeters = picas × 4.23333333333. Reversed, picas = millimeters ÷ 4.23333333333, which is the same as multiplying by 0.236220472441.
Which is the bigger unit, the pica or the millimeter?
The pica. One pica equals 4.23333 millimeters.
What does this quantity actually measure?
Both units measure length. That is why a single factor is enough: there is no temperature offset and no material property involved, unlike conversions that cross between different quantities.
What is a pica?
Twelve points, or 1/6 inch — the column-width unit of print layout.
What is a millimeter?
One thousandth of a metre — the finest gradation on a standard ruler.
Why does my answer differ from another converter?
Almost always because the other tool rounded the factor before multiplying. This page keeps full double precision through the calculation and rounds only for display, and it prints the factor it used so you can see where any difference came from.
Is there a quick way to do pica to mm in my head?
Plenty of people do this in their head: multiply by 4.2 instead of using the exact factor 4.233333333. At 100 that shortcut gives 420 millimeters, off by 3.333 millimeters or about 0.79%. Fine for a rough estimate, not fine for anything you are cutting to size or dosing.
Picas to millimeters reference tables
| Picas | Millimeters |
|---|---|
| 0.5 pica | 2.11667 mm |
| 1 pica | 4.23333 mm |
| 2 pica | 8.46667 mm |
| 3 pica | 12.7 mm |
| 5 pica | 21.1667 mm |
| 10 pica | 42.3333 mm |
| 20 pica | 84.6667 mm |
| 25 pica | 105.833 mm |
| 50 pica | 211.667 mm |
| 75 pica | 317.5 mm |
| 100 pica | 423.333 mm |
| 250 pica | 1058.33 mm |
| 500 pica | 2116.67 mm |
| 1000 pica | 4233.33 mm |
| 5000 pica | 21,166.7 mm |
Exact factor: 1 pica = 4.23333333333 millimeters.
| Quantity | pica | mm |
|---|---|---|
| A credit card’s long edge | 20.22 pica | 85.6 mm |
| A door height | 480 pica | 2032 mm |
| An Olympic pool | 1.181e+04 pica | 5e+04 mm |
| The Eiffel Tower | 7.795e+04 pica | 3.3e+05 mm |
| A marathon | 9.967e+06 pica | 4.22e+07 mm |
| Earth’s diameter | 3.01e+09 pica | 1.274e+10 mm |
Published reference values, converted with the same factor this page uses.