Calculator + chartEnter your measurements below and it works the answer out.
Between every inch there are 15 marks. The longest is the half, the next longest the quarters, then the eighths, then the tiny sixteenths. Count which mark you are on, pick it below, and the reader gives the exact measurement three ways.
| Mark | Fraction | Decimal | Millimetres | Length of the line |
|---|---|---|---|---|
| 1 | 1/16 | 0.0625 | 1.6 | shortest |
| 2 | 1/8 | 0.125 | 3.2 | short |
| 3 | 3/16 | 0.1875 | 4.8 | shortest |
| 4 | 1/4 | 0.25 | 6.4 | medium |
| 5 | 5/16 | 0.3125 | 7.9 | shortest |
| 6 | 3/8 | 0.375 | 9.5 | short |
| 7 | 7/16 | 0.4375 | 11.1 | shortest |
| 8 | 1/2 | 0.5 | 12.7 | long |
| 9 | 9/16 | 0.5625 | 14.3 | shortest |
| 10 | 5/8 | 0.625 | 15.9 | short |
| 11 | 11/16 | 0.6875 | 17.5 | shortest |
| 12 | 3/4 | 0.75 | 19.1 | medium |
| 13 | 13/16 | 0.8125 | 20.6 | shortest |
| 14 | 7/8 | 0.875 | 22.2 | short |
| 15 | 15/16 | 0.9375 | 23.8 | shortest |
| 16 | 1 in | 1.0 | 25.4 | inch line, numbered |
Some tapes add 32nds in the first foot — a mark between every mark above. Ignore them unless you are doing fine woodwork.
The lines get shorter as the fraction gets smaller. Inch lines are longest and numbered; the half-inch line is next; quarter lines are shorter; eighth lines shorter still; sixteenth lines are the tiny ones. To read a mark, find the inch before it, then count marks — or judge by line length: a medium line just past 5 is 5¼, a long one is 5½.
Reduce the fraction. The 8th mark is 8/16, which is ½; the 4th is 4/16 = ¼; the 12th is 12/16 = ¾. The reader does this for you.
Other marks on the tape. A black diamond or a red number every 16 inches marks stud spacing (16 in on centre); red numbers or arrows every 19.2 inches mark truss spacing (five per 8 ft). The hook at the end slides by exactly its own thickness so that a push measurement and a pull measurement both read true — do not "fix" a loose hook.
Sixteenths of an inch. Between each inch there are 15 lines: the half (longest), two quarters, four eighths and eight sixteenths (shortest). Some tapes also show thirty-seconds in the first foot.
Find the inch, then count six small marks past it — or look for the second short (eighth) line after the quarter line. 3/8 is 0.375 in, about 9.5 mm.
19.2-inch truss spacing: five trusses in 8 feet. The red 16, 32, 48… numbers are 16-inch stud spacing.
On purpose. It slides by the thickness of the hook so a measurement taken by hooking over an edge and one taken by pushing against a wall both read correctly.