30 mm is about 1.181 inches, or about 1 3/16 inch (slightly less). It is exactly 3 cm. Divide millimeters by 25.4, because 1 inch is defined as exactly 25.4 mm.
30 mm ≈ 1 3/16″
Slightly less than 1 3/16″ (by 0.16 mm) · ≈ 1.181 in
- Inches
- ≈ 1.1811 in
- Nearest 1/16″
- 1 3/16″ 30 mm is 0.16 mm shorter
- Nearest 1/32″
- 1 3/16″ 30 mm is 0.16 mm shorter
- Nearest 1/64″
- 1 3/16″ 30 mm is 0.16 mm shorter
How big is 30 mm?
30 mm = 30 ÷ 25.4 in ≈ 1.18110 in. On a tape measure that is 1 3/16 in (1.1875 in, 30.162 mm), and 30 mm is shorter than that by about 0.16 mm. In other metric units, 30 mm is exactly 3 cm and exactly 0.03 m.
Compared with common fractions: 1 3/16 in is 30.163 mm, so 30 mm is about 0.16 mm less; 1 1/4 in is 31.75 mm, so 30 mm is 1.75 mm less.
Things that are about 30 mm
These are nominal sizes. Real parts vary a little with the maker, so check the part when fit matters.
An M30 bolt or screw
The “M30” label means a thread diameter of 30 mm, about 1.18 inches.
A US quarter
A US 25-cent coin is 24.26 mm across, so it is 5.74 mm narrower than 30 mm.
A US half dollar
A US 50-cent coin is 30.61 mm across, so it is 0.61 mm wider than 30 mm.
One and a quarter inches
1 1/4 in is exactly 31.75 mm, so it is 1.75 mm longer than 30 mm.
3 cm on a ruler
30 mm is exactly 3 cm, three of the numbered gaps on a metric ruler.
Nearby millimeter sizes
Decimals are rounded to 3 places. In the fraction columns, + means the value is slightly longer than the fraction, − slightly shorter, and = exact.
| Millimeters (mm) | Inches (decimal) | Nearest 1/16″ | Nearest 1/32″ |
|---|---|---|---|
| 25 mm | 0.984 | 1″ − | 31/32″ + |
| 26 mm | 1.024 | 1″ + | 1 1/32″ − |
| 27 mm | 1.063 | 1 1/16″ + | 1 1/16″ + |
| 28 mm | 1.102 | 1 1/8″ − | 1 3/32″ + |
| 29 mm | 1.142 | 1 1/8″ + | 1 5/32″ − |
| 30 mm | 1.181 | 1 3/16″ − | 1 3/16″ − |
| 31 mm | 1.22 | 1 1/4″ − | 1 7/32″ + |
| 32 mm | 1.26 | 1 1/4″ + | 1 1/4″ + |
| 33 mm | 1.299 | 1 5/16″ − | 1 5/16″ − |
| 34 mm | 1.339 | 1 5/16″ + | 1 11/32″ − |
| 35 mm | 1.378 | 1 3/8″ + | 1 3/8″ + |
Frequently asked questions
How many inches is 30 mm?
30 mm is about 1.181 inches (1.1811 in), or about 1 3/16 inch, slightly less.
What is 30 mm as a fraction of an inch?
About 1 3/16 inch. 30 mm is 1.1811 in and 1 3/16 in is 1.1875 in, so 30 mm is slightly less.
Is 30 mm the same as 1 1/4 inch?
No. 1 1/4 inch is 31.75 mm, so 30 mm is 1.75 mm smaller.
How many mm is a US half dollar?
A US half dollar is 30.61 mm across, about 0.61 mm more than 30 mm.
How many cm is 30 mm?
30 mm is exactly 3 cm, because 1 cm is 10 mm.
How do I convert mm to inches?
Divide the millimeters by 25.4. For 30 mm, 30 ÷ 25.4 ≈ 1.181 inches.