How do I read a fraction of an inch as a decimal?

Divide the top of the fraction by the bottom. So 3/8 is 3 ÷ 8 = 0.375, and 2 5/16 is 2 + 5 ÷ 16 = 2.3125. This tool reads whole-and-fraction and feet-inches shapes as well, so you can type what is written on the drawing and get the decimal straight back.

How do I go from a decimal back to a tape fraction?

Type the decimal in the second box and the tool snaps it to the nearest sixteenth and thirty-second, the marks a tape actually carries. A reading of 0.4 inch, for instance, comes out as 3/8 to the sixteenth — the nearest line you can cut to.

What input shapes does it understand?

Bare inches like 7, fractions like 5/8, whole-and-fraction like 3 5/8, and feet-inches like 12′ 3 5/8″ or 12′-3-5/8. A dash inside the inches is treated as a separator, not a minus, which is how framing dimensions are usually scribbled.

Why round to sixteenths and thirty-seconds?

Because that is what the tool in your hand is graduated in. A decimal like 0.418 inch means nothing at the saw; 7/16 does. The exact decimal stays on screen for setups that read thousandths, but the fraction is what you mark and cut.

Fractions de pouce en décimales

This reads and rounds the number you type — nothing more. The fraction is snapped to the nearest tape mark, so on a precision setup work from the decimal instead. Measure against the actual part before you cut.

Type a fraction, a whole-and-fraction, or a feet-inches dimension and the decimal appears at once. Type a decimal in the second box and it comes back as the nearest sixteenth and thirty-second — the two marks you are most likely to be cutting to. The millimetre figure rides along for metric tooling; set the site to metric and it becomes the big readout.

Exemple détaillé

A cut list reads 2 5/16″. That is 2 + 5 ÷ 16 = 2.3125 in. Now suppose a CNC setup gives you 2.28 inch and you need a tape mark: to the nearest sixteenth that is 2 5/16″, and to the nearest thirty-second 2 9/32″. For metric tooling, 2 5/16″ is 2.3125 × 25.4 = 58.74 mm.

Exercez-vous

Quick referencefor tape fractions

Sixteenths: 1/16 .0625 · ⅛ .125 · 3/16 .1875 · ¼ .25 · 5/16 .3125 · ⅜ .375 · 7/16 .4375 · ½ .5
: 9/16 .5625 · ⅝ .625 · 11/16 .6875 · ¾ .75 · 13/16 .8125 · ⅞ .875 · 15/16 .9375
Decimal to sixteenths: × 16, round, put it over 16
In millimetres: 1/16 1.59 · ⅛ 3.18 · ¼ 6.35 · ⅜ 9.53 · ½ 12.7 · ¾ 19.05 · 1 in 25.4 (inches × 25.4)
Inches to decimal feet: ÷ 12 · 3 in = 0,25 ft · 6 in = 0,5 · 9 in = 0,75 · 8′ 9″ = 8,75 ft
Surveyor's tenths: 0,1 ft = 1,2 in · 0,5 ft = 6 in · 0,83 ft ≈ 10 in

Mistakes to catchbefore you trust the number

Typing 2 5/16 as 25/16 — the space matters; the second is 1.5625.
Reading a decimal as a fraction of a foot: 9.5 on a plan is nine and a half inches only if the plan is in inches; on a decimal-feet survey it is 9 ft 6 in.
Rounding a rounded number again: convert once to the nearest sixteenth and mark the tape from that, not from a figure already rounded to tenths.

La formule

decimal = whole + numerator ÷ denominator

A fraction is just a division waiting to happen, and feet add twelve inches apiece. Going back the other way, the decimal is multiplied by 16 (or 32), rounded to a whole number of ticks, and reduced — which is exactly how a tape's markings are laid out.

Questions

How do I read a fraction of an inch as a decimal?: Divide the top of the fraction by the bottom. So 3/8 is 3 ÷ 8 = 0.375, and 2 5/16 is 2 + 5 ÷ 16 = 2.3125. This tool reads whole-and-fraction and feet-inches shapes as well, so you can type what is written on the drawing and get the decimal straight back.
How do I go from a decimal back to a tape fraction?: Type the decimal in the second box and the tool snaps it to the nearest sixteenth and thirty-second, the marks a tape actually carries. A reading of 0.4 inch, for instance, comes out as 3/8 to the sixteenth — the nearest line you can cut to.
What input shapes does it understand?: Bare inches like 7, fractions like 5/8, whole-and-fraction like 3 5/8, and feet-inches like 12′ 3 5/8″ or 12′-3-5/8. A dash inside the inches is treated as a separator, not a minus, which is how framing dimensions are usually scribbled.
Why round to sixteenths and thirty-seconds?: Because that is what the tool in your hand is graduated in. A decimal like 0.418 inch means nothing at the saw; 7/16 does. The exact decimal stays on screen for setups that read thousandths, but the fraction is what you mark and cut.

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