To convert points to chains, multiply by 1.753647587e-05. That factor is the whole relationship: both units measure length, so the conversion is a proportion with no offset and no substance-specific constant.
The DTP point: exactly 1/72 inch, the unit type size is set in. Sixty-six feet — the length of a cricket pitch, and the unit the US Public Land Survey was laid out in.
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". Two tables follow: rounded steps for quick lookup, and a set of real reference quantities converted into chains, which is usually more useful than the bare number.
The formula
points- The amount you are converting, in points
1.75364758698e-05- The exact number of chains in one point
chains- The converted result
How it works, step by step
- Enter the value in points.
- It is multiplied by 1.75364758698e-05, the exact factor between the two units.
- The answer is shown in chains, with the reverse conversion beneath it.
- Check the reference table if you want a figure of comparable size.
Worked examples
An Olympic pool: 1.42e+05 pt in chains
Take an olympic pool, roughly 1.42e+05 pt. The conversion is a single multiplication — 1.42e+05 × 1.75365e-05 — giving 2.49018 ch. Because the relationship is proportional, doubling the input doubles the answer to 4.98036 ch.
A credit card’s long edge: 243 pt in chains
Take a credit card’s long edge, roughly 243 pt. The conversion is a single multiplication — 243 × 1.75365e-05 — giving 0.00426136 ch. Because the relationship is proportional, doubling the input doubles the answer to 0.00852273 ch.
How to read your score
Frequently asked questions
How many chains are in one point?
Exactly 1.75364758698e-05. 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 points to chains?
chains = points × 1.75364758698e-05. Reversed, points = chains ÷ 1.75364758698e-05, which is the same as multiplying by 57,024.
Which is the bigger unit, the point or the chain?
The chain. One point is only 1.75365e-05 of a chain, so it takes 57,024 points to make one chain.
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 point?
The DTP point: exactly 1/72 inch, the unit type size is set in.
What is a chain?
Sixty-six feet — the length of a cricket pitch, and the unit the US Public Land Survey was laid out in.
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 pt to ch in my head?
Plenty of people do this in their head: divide by 57,000 instead of using the exact factor 0.000018. At 100 that shortcut gives 0.001754386 chains, off by 0.000001 chains or about 0.04%. Fine for a rough estimate, not fine for anything you are cutting to size or dosing.
Points to chains reference tables
| Points | Chains |
|---|---|
| 0.5 pt | 8.76824e-06 ch |
| 1 pt | 1.75365e-05 ch |
| 2 pt | 3.5073e-05 ch |
| 3 pt | 5.26094e-05 ch |
| 5 pt | 8.76824e-05 ch |
| 10 pt | 0.000175365 ch |
| 20 pt | 0.00035073 ch |
| 25 pt | 0.000438412 ch |
| 50 pt | 0.000876824 ch |
| 75 pt | 0.00131524 ch |
| 100 pt | 0.00175365 ch |
| 250 pt | 0.00438412 ch |
| 500 pt | 0.00876824 ch |
| 1000 pt | 0.0175365 ch |
| 5000 pt | 0.0876824 ch |
Exact factor: 1 point = 1.75364758698e-05 chains.
| Quantity | pt | ch |
|---|---|---|
| A credit card’s long edge | 242.6 pt | 0.004255 ch |
| A door height | 5760 pt | 0.101 ch |
| An Olympic pool | 1.417e+05 pt | 2.485 ch |
| The Eiffel Tower | 9.354e+05 pt | 16.4 ch |
| A marathon | 1.196e+08 pt | 2098 ch |
| Earth’s diameter | 3.612e+10 pt | 6.334e+05 ch |
Published reference values, converted with the same factor this page uses.