mm to inches fraction
Convert mm to inches as a fraction. Type millimeters (or an inch value) to get decimal inches plus the nearest 1/64, 1/32, and 1/16 fractional inches. Same engine as the mm to inches hub — this page is the fraction-first view. Going the other way, the inch to mm hub converts fraction inches to millimeters (1 in = 25.4 mm), including 1/2, 5/8, 3/4 and 1 1/4.
- Decimal inches
- 0.1969
- Nearest 1/64
- 13/64 in (+0.159 mm)
- Nearest 1/32
- 3/16 in (−0.238 mm)
- Nearest 1/16
- 3/16 in (−0.238 mm)
- Feet + inches
- 0 ft 0.197 in
Fractions are rounded to the nearest 1/64, 1/32, or 1/16 tick. Decimal inches stay exact.
mm to frac calculator
The calculator above is a mm to frac calculator: millimeters in, fractional inches out. You can also type an inch decimal or mixed fraction (1/16, 3 1/2) and read the matching millimeters. Decimal inches are exact (1 in = 25.4 mm). Each fraction column is the nearest tick at that grid — not a second exact size.
How to convert mm to fractions
Divide by 25.4 for decimal inches, then round the leftover to the grid you need. Shop charts and tapes are usually 64ths; coarser tapes stop at 32nds or 16ths.
Worked example: 5 mm
- 5 ÷ 25.4 = 0.1969 in (exact decimal).
- Fractional part 0.196850 × 64 = 12.5984 → nearest integer 13.
- Nearest 1/64 = 13/64 in (+0.159 mm from exact).
- Same leftover on coarser grids: nearest 1/32 = 3/16 in, nearest 1/16 = 3/16 in.
100 mm works the same way: 3.9370 in, nearest 1/64 3 15/16 in. Full decimal + 1/64 tables through 3000 mm stay on the mm to inches hub.
mm to fractional inches chart
Each row is mm → exact decimal inches, then nearest 1/64, 1/32, and 1/16. Print these tables (or save as PDF) when you need a searchable, interactive-style chart instead of a static vendor PDF.
0–25 mm (every 1 mm)
| mm | inches (decimal) | nearest 1/64 | nearest 1/32 | nearest 1/16 |
|---|---|---|---|---|
| 0 | 0.0000 | 0 | 0 | 0 |
| 1 | 0.0394 | 3/64 | 1/32 | 1/16 |
| 2 | 0.0787 | 5/64 | 3/32 | 1/16 |
| 3 | 0.1181 | 1/8 | 1/8 | 1/8 |
| 4 | 0.1575 | 5/32 | 5/32 | 3/16 |
| 5 | 0.1969 | 13/64 | 3/16 | 3/16 |
| 6 | 0.2362 | 15/64 | 1/4 | 1/4 |
| 7 | 0.2756 | 9/32 | 9/32 | 1/4 |
| 8 | 0.3150 | 5/16 | 5/16 | 5/16 |
| 9 | 0.3543 | 23/64 | 11/32 | 3/8 |
| 10 | 0.3937 | 25/64 | 13/32 | 3/8 |
| 11 | 0.4331 | 7/16 | 7/16 | 7/16 |
| 12 | 0.4724 | 15/32 | 15/32 | 1/2 |
| 13 | 0.5118 | 33/64 | 1/2 | 1/2 |
| 14 | 0.5512 | 35/64 | 9/16 | 9/16 |
| 15 | 0.5906 | 19/32 | 19/32 | 9/16 |
| 16 | 0.6299 | 5/8 | 5/8 | 5/8 |
| 17 | 0.6693 | 43/64 | 21/32 | 11/16 |
| 18 | 0.7087 | 45/64 | 23/32 | 11/16 |
| 19 | 0.7480 | 3/4 | 3/4 | 3/4 |
| 20 | 0.7874 | 25/32 | 25/32 | 13/16 |
| 21 | 0.8268 | 53/64 | 13/16 | 13/16 |
| 22 | 0.8661 | 55/64 | 7/8 | 7/8 |
| 23 | 0.9055 | 29/32 | 29/32 | 7/8 |
| 24 | 0.9449 | 15/16 | 15/16 | 15/16 |
| 25 | 0.9843 | 63/64 | 31/32 | 1 |
26–50 mm (every 1 mm)
| mm | inches (decimal) | nearest 1/64 | nearest 1/32 | nearest 1/16 |
|---|---|---|---|---|
| 26 | 1.0236 | 1 1/32 | 1 1/32 | 1 |
| 27 | 1.0630 | 1 1/16 | 1 1/16 | 1 1/16 |
| 28 | 1.1024 | 1 7/64 | 1 3/32 | 1 1/8 |
| 29 | 1.1417 | 1 9/64 | 1 5/32 | 1 1/8 |
| 30 | 1.1811 | 1 3/16 | 1 3/16 | 1 3/16 |
| 31 | 1.2205 | 1 7/32 | 1 7/32 | 1 1/4 |
| 32 | 1.2598 | 1 17/64 | 1 1/4 | 1 1/4 |
| 33 | 1.2992 | 1 19/64 | 1 5/16 | 1 5/16 |
| 34 | 1.3386 | 1 11/32 | 1 11/32 | 1 5/16 |
| 35 | 1.3780 | 1 3/8 | 1 3/8 | 1 3/8 |
| 36 | 1.4173 | 1 27/64 | 1 13/32 | 1 7/16 |
| 37 | 1.4567 | 1 29/64 | 1 15/32 | 1 7/16 |
| 38 | 1.4961 | 1 1/2 | 1 1/2 | 1 1/2 |
| 39 | 1.5354 | 1 17/32 | 1 17/32 | 1 9/16 |
| 40 | 1.5748 | 1 37/64 | 1 9/16 | 1 9/16 |
| 41 | 1.6142 | 1 39/64 | 1 5/8 | 1 5/8 |
| 42 | 1.6535 | 1 21/32 | 1 21/32 | 1 5/8 |
| 43 | 1.6929 | 1 11/16 | 1 11/16 | 1 11/16 |
| 44 | 1.7323 | 1 47/64 | 1 23/32 | 1 3/4 |
| 45 | 1.7717 | 1 49/64 | 1 25/32 | 1 3/4 |
| 46 | 1.8110 | 1 13/16 | 1 13/16 | 1 13/16 |
| 47 | 1.8504 | 1 27/32 | 1 27/32 | 1 7/8 |
| 48 | 1.8898 | 1 57/64 | 1 7/8 | 1 7/8 |
| 49 | 1.9291 | 1 59/64 | 1 15/16 | 1 15/16 |
| 50 | 1.9685 | 1 31/32 | 1 31/32 | 1 15/16 |
Does 5 mm equal 1/4 inch?
No. 5 mm = 0.1969 in. 1/4 in = 6.35 mm — 1.35 mm larger. The nearest 1/64 to 5 mm is 13/64 in, not 1/4 in (16/64).
4 mm = 0.1575 in; nearest 1/64 is 5/32 in (same row as the chart). There is no dedicated 4 mm value page yet — use this calculator and table for that size.
Related pages
FAQ
How does rounding mm to 1/32 and 1/16 fractions work?
Divide millimeters by 25.4 to get decimal inches (exact), then round the fractional part to the nearest 1/64 — the tick used on most inch rulers and bit charts. Example: 5 mm ÷ 25.4 = 0.1969 in; the nearest 1/64 is 13/64 in. Coarser charts use the nearest 1/32 or 1/16 instead. The decimal is exact; the fraction is an approximation and can disagree by a fraction of a millimeter.
Why isn't 5 mm 1/4 inch on a fraction chart?
No. 5 mm = 0.1969 in, while 1/4 in = 6.35 mm — a difference of 1.35 mm. On a 1/64 chart the nearest tick to 5 mm is 13/64 in, not 1/4 in (which is 16/64). Use a true 5 mm size when the drawing is metric.
What is 5 mm in fractional inches?
5 mm = 0.1969 in exactly. The nearest 1/64 is 13/64 in — about 0.159 mm larger than exact 5 mm. That is not 1/4 in (6.35 mm). The nearest 1/32 and 1/16 are both 3/16 in. The decimal column is the exact size; the fraction is the nearest ruler tick.
What is 4 mm in fractional inches?
4 mm = 0.1575 in exactly. The nearest 1/64 is 5/32 in (10/64) — about 0.031 mm smaller than exact 4 mm. The nearest 1/32 is also 5/32 in; the nearest 1/16 is 3/16 in. Use a true 4 mm size when the drawing is metric.