Feet-inch construction calculator
The pocket calculator a framer carries, on screen. Type 12 Feet 6 Inch 1/2 and add it to another length, multiply two lengths into square feet, convert to metric, or give it any two of pitch, rise, run and diagonal and read off the other two.
Diag
Keyboard works too: ' for feet, " for inches, a space before a fraction.
Fractions to the nearest
The same length in
- Feet and inches
- 15' 7 13/16"
- Inches
- 187 13/16"
- Decimal feet
- 15.6525 ft
- Yards
- 5.2175 yd
- Meters
- 4.7709 m
- Centimeters
- 477.09 cm
- Millimeters
- 4770.9 mm
The right triangle
Type a measurement and press a side to enter it. Any two solve the other two; press a side with nothing typed to read it back.
- Pitchentered
- 6 in 12 · 26.57°
- Rise
- 7' 0"
- Runentered
- 14' 0"
- Diagonal
- 15' 7 13/16"
Tape
- 12' 6 1/2" + 7' 9 3/4" = 20' 4 1/4"
- Pitch = 6 in 12
- Run = 14' 0"
- Diag → 15' 7 13/16"
Stairs, hips and compound miters
This keypad does the arithmetic and the one triangle. The jobs that need more than that have their own calculators, with the checks built in: stair stringers, rafters, hips and jacks, crown and compound miters and arcs and circles.
Using the keypad
- How do I add feet and inches on this calculator?
- Type the feet and press Feet, type the inches and press Inch, then the fraction with the / key: 12 Feet 6 Inch 1/2, then +, then 7 Feet 9 Inch 3/4, then =. The display reads 20' 4 1/4". A number after Feet with no unit of its own is taken as inches, so 12 Feet 6 is twelve-six, the way it is said out loud.
- How do I find the length of a rafter from the pitch and the run?
- Enter the two you know and press the side you want. 6 Pitch, 14 Feet Run, then Diag with nothing typed reads 15' 7 13/16", and Rise reads 7' 0". Any two of pitch, rise, run and diagonal solve the other two. The diagonal is the line length from the plate to the ridge, before the ridge deduction or the tail, which the rafter calculator adds.
- What happens if I add a number with no unit to a length?
- It takes the unit the length is showing in, the way a pocket construction calculator does. 5 Feet + 3 reads 8' 0", because the display was in feet; 12 Inch + 3 reads 15", because it was in inches. If you meant three inches on a length shown in feet, say so: 5 Feet + 3 Inch reads 5' 3". Multiplying two lengths is different: it gives an area, not a longer length.
- Can it work out square feet and cubic yards?
- Yes. Every value carries its dimension, so 12 Feet × 10 Feet reads 120 sq ft, and multiplying by a third length gives a volume: a 10' by 10' slab 4" thick is 33.333 cu ft, and pressing Yds then reads 1.235 cu yd. That is the slab before any allowance for waste or an uneven subgrade.
- How do I work out the circumference, area or an arc of a circle?
- Type the diameter with its unit and press Circ: 10 Feet Circ reads 31' 5" around, and Circ again reads the area, 78.54 sq ft. With that circle stored, an angle and Arc gives the length of edge it covers: 90 Arc is a quarter of the way around, 7' 10 1/4". For an arc you know only by its chord and how high it rises, the circle and arc layout calculator works the radius out first.
- How do I convert inches to millimeters or meters?
- Type the length with its unit and press the unit you want: 1 Inch, then mm, reads 25.4 mm, and 1 Yds, then m, reads 0.9144 m. Both are exact, because an inch is defined as 25.4 mm. Feet toggles between feet and inches and decimal feet, and the table under the keypad shows the display in every unit at once.
You might also need
- Inch fraction calculatorAdd or subtract two measurements written the way a tape shows them, read to the nearest sixteenth, thirty-second or sixty-fourth.
- RaftersCommon, hip and jack rafters for any pitch, with the birdsmouth laid out and the cut angles alongside.
- Stair stringersDivide the rise into even risers, lay out the notches, and check the result against the code.
- Concrete footings and slabsCubic yards for a run of post footings or a slab, and the bags of ready-mix that buys.