Home › Tools › Add fractions › 5/16 + 15/16

5/16" + 15/16"

Adding two fractions of an inch, exactly — the everyday jobsite arithmetic that a decimal calculator gets wrong. Reduced, carried, and shown in millimetres.

5/16" + 15/16" =

=1-1/4"

Sum

1-1/4"

Decimal inch

1.25"

Millimetres

31.75 mm

5/16" − 15/16"

-0-5/8"

The work

Over a common denominator

Put both over 16: 5/16 = 5/16 and 15/16 = 15/16. Add the tops: 5/16 + 15/16 = 20/16, which carries past one inch. Reduced, that's 1-1/4" (1.25 inches). TapeMath tracks it as an exact fraction, so it lands dead on the tape mark.

Keep going

5/16" to decimal 15/16" to decimal All fraction sums Add it on the calculator

The same math, offline

Every calc, on your tape measure — even with no signal.

TapeMath for iPhone runs this exact engine offline, adds rafters, stairs, studs, pitch and a paperless tape, and the key layout your thumbs already know. $9.99 once — no subscription, ever.

See the app

Coming soon — TapeMath is in final App Review. Meanwhile, use the free web calculator →