CSS units·50px
50px =
3.125rem
37.5pt

50 px in rem — 3.125 rem, 37.5 pt

50 px is 3.125 rem and 37.5 pt — 0.52083 inches, 13.229 mm, and 312.5% of the root font size.

rem (root 16 px)
3.125rem
pt (points)
37.5pt
pc (picas)
3.125pc
percent of root
312.5%
inches
0.52083in
millimetres
13.229mm
centimetres
1.3229cm

Why rem divides by 16

Because browsers default the root font size to 16 px, and rem is a multiple of it. When a reader enlarges text in their browser settings, only the parts written in rem grow — anything pinned in px stays put.

Nearby sizes

pxrem (root 16 px)pt (points)
47px2.9375rem35.25pt
48px3rem36pt
49px3.0625rem36.75pt
50px3.125rem37.5pt
51px3.1875rem38.25pt
52px3.25rem39pt
53px3.3125rem39.75pt

On screen, pt and inches are still pixels

CSS fixes one inch at 96 px and one point at 1/72 inch. So 16 px is exactly 12 pt — but hold a ruler to the screen and that "inch" will not measure an inch.

Sizes you meet most

Body text at 16, small text at 14, spacing at 8, 24 and 32 — the values that keep coming back.

How to read this

  • rem = px ÷ 16, because browsers default the root font size to 16 px.
  • pt = px × 0.75, since CSS fixes an inch at 96 px and a point at 1/72 inch.
  • One pc is 12 pt, and one inch is both 96 px and 72 pt.
  • Use rem for text and spacing; keep px for hairlines such as borders.

Frequently asked questions

Q. How many rem is 50 px?

3.125 rem — that is 50 divided by 16.

Q. How many points is 50 px?

37.5 pt. A point is 1/72 inch and an inch is 96 px, so you multiply by 0.75.

Q. What length is that?

0.52083 inches, or 13.229 mm — though a ruler on the screen will not agree.

Q. And as a percentage?

312.5% of the root font size.