20 inches at a glance
- Centimeters
- 50.8 cm
- Millimeters
- 508 mm
- Meters
- 0.508 m
- Feet & inches
- 1 ft 8 in
- Feet (decimal)
- 1.6667 ft
- Nearest whole cm
- 51 cm
How to convert 20 inches to cm
cm = inches × 2.54
20 × 2.54 = 50.8 cm
20 × 2.54 = 50.8 cm
Because the inch is defined as exactly 2.54 cm, 50.8 cm is exact — no rounding involved. To do it in your head, split 2.54 into 2.5 + 0.04: 20 × 2.5 = 50 and 20 × 0.04 = 0.8, which add up to 50.8.
Fractions of an inch around 20 in
Tape measures between 20 and 21 in are marked in eighths. Each eighth adds 3.175 mm:
| Inches | Centimeters | Millimeters |
|---|---|---|
| 20 | 50.8 | 508 |
| 20 1/8 | 51.1175 | 511.175 |
| 20 1/4 | 51.435 | 514.35 |
| 20 3/8 | 51.7525 | 517.525 |
| 20 1/2 | 52.07 | 520.7 |
| 20 5/8 | 52.3875 | 523.875 |
| 20 3/4 | 52.705 | 527.05 |
| 20 7/8 | 53.0225 | 530.225 |
20 inches in real life
- Bike wheels. 20-inch wheels are named for the approximate outside diameter of the tire, about 50.8 cm.
- Screens. A 20-inch 16:9 screen (measured diagonally) is 50.8 cm across the diagonal, about 17.4 × 9.8 in (44.3 × 24.9 cm) for the picture itself.
Objects of a similar size
- About the same as the length of a typical newborn baby, 50 cm (19.69 in).
- 9% shorter than the 22-inch carry-on length limit on most US airlines, 55.88 cm (22 in).
- 33% longer than the height of a bowling pin, 38.1 cm (15 in).
Inches near 20 in
| Inches | Centimeters | Feet & inches / mm |
|---|---|---|
| 15 in | 38.1 cm | 1 ft 3 in |
| 16 in | 40.64 cm | 1 ft 4 in |
| 17 in | 43.18 cm | 1 ft 5 in |
| 18 in | 45.72 cm | 1 ft 6 in |
| 19 in | 48.26 cm | 1 ft 7 in |
| 20 in | 50.8 cm | 1 ft 8 in |
| 21 in | 53.34 cm | 1 ft 9 in |
| 22 in | 55.88 cm | 1 ft 10 in |
| 23 in | 58.42 cm | 1 ft 11 in |
| 24 in | 60.96 cm | 2 ft |
| 25 in | 63.5 cm | 2 ft 1 in |
Going the other way: 51 cm to inches is 20.08 in.
Frequently asked questions
How many cm is 20 inches?
20 inches is exactly 50.8 cm, because one inch is defined as 2.54 cm.
What is 20 inches in mm?
20 in = 508 mm (multiply by 25.4).
How many feet is 20 inches?
20 in is 1.6667 feet, or 1 ft 8 in.
Is 20 inches the same as 51 cm?
Not quite: 20 in is 50.8 cm, so 51 cm is 2 mm too long — close enough for most everyday measuring.