How to use
- Choose the unit you have (pt, px, mm, em or %) and enter the size.
- Every other unit is shown at once, with a preview at that size.
- For em, rem and %, set the base font size — browsers default to 16 px.
Options explained
- Points and pixels
- A point is 1/72 inch and CSS defines a pixel as 1/96 inch, so 1 pt = 4/3 px and 12 pt = 16 px.
- Millimetres
- 1 pt = 25.4 ÷ 72 ≈ 0.353 mm. This is the physical size of the type body and applies when printing.
- em, rem and percent
- A multiple of the base font size. With a 16 px base, 1 em = 1 rem = 100% = 16 px = 12 pt.
- Chinese size (号)
- Chinese word processors name sizes instead of using points, from 初号 (42 pt) down to 八号 (5 pt). You can convert to and from these too.
Common sizes
| pt | px | em (16 px base) |
|---|---|---|
| 9 | 12 | 0.75 |
| 10.5 | 14 | 0.875 |
| 12 | 16 | 1 |
| 14 | 18.67 | 1.1667 |
| 18 | 24 | 1.5 |
| 24 | 32 | 2 |
Web sizes in pixels, points and rem
With the browser default of 16 px as the base size:
| Pixels | Points | rem / em | Typical use |
|---|---|---|---|
| 12 px | 9 pt | 0.75 rem | Captions, footnotes |
| 14 px | 10.5 pt | 0.875 rem | Small text, labels |
| 16 px | 12 pt | 1 rem | Body text |
| 18 px | 13.5 pt | 1.125 rem | Large body text, lead paragraphs |
| 20 px | 15 pt | 1.25 rem | Small headings |
| 24 px | 18 pt | 1.5 rem | Headings |
| 32 px | 24 pt | 2 rem | Page titles |
Which unit to use
pt (points) are for print and word processors: 1 pt is 1/72 of an inch, so 12 pt text is the same physical size on any printer.
px (CSS pixels) are for screens: 1 px is defined as 1/96 inch at normal zoom, which makes 12 pt equal to 16 px.
rem and em are relative. 1 rem is the root font size (usually 16 px); 1 em is the font size of the parent element. Using rem for text lets people who set a larger default font in their browser get bigger text everywhere.
Millimetres help when matching a printed sample: measure the height of a capital letter and the body size is roughly 1.4 times that, depending on the typeface.
Frequently asked questions
How many pixels is 12 pt?
16 px. Multiply points by 4/3 to get CSS pixels, or pixels by 0.75 to get points.
What is the difference between em and rem?
rem is relative to the root (html) font size; em is relative to the font size of the parent element. With no font size set anywhere, both are 16 px.
Why does text measured on screen not match the conversion?
A CSS pixel is a logical unit defined at 96 DPI. The physical size on screen depends on the display's pixel density and the system zoom. Points and millimetres are only exact in print.
Privacy
This tool runs entirely in your browser. Your files and text are processed on your device and are never uploaded to our servers.