How to use the tape measure fraction calculator
Enter a measurement as feet, inches, and a fraction of an inch — the numerator and denominator, exactly as marked on a tape measure — pick Add or Subtract, and tap Add to list. Every entry joins a running total shown in feet-inches-fraction, decimal inches, and millimetres, rounded to whichever precision you choose.
The ruler below the total shows exactly where that measurement falls between two whole inches, the same way you'd read it off a real tape. Tap Go advanced to multiply the running total by a number, or split it into equal parts for evenly spaced marks along a board.
Why fractions, not decimals
A tape measure doesn't show 5.625 inches — it shows 5 5/8", marked between the 5 and 6 inch lines. Converting back and forth from decimals wastes time and invites rounding errors. This calculator works directly in the fractions a tape measure actually uses, and only converts to decimal inches and millimetres as a secondary reference.
Choosing a rounding precision
Most tape measures mark down to 1/16 inch, which is the default here. Rough framing and deck work is usually fine at 1/8 inch. Fine woodworking, cabinetry, and joinery often call for 1/32 or 1/64 inch, where a standard tape can't help and a machinist's rule or digital caliper takes over.
Adding and subtracting a cut list
Add every board or offcut in a project as its own entry — each one keeps its sign, so a subtracted piece reduces the running total instead of adding to it. This is the same running-total approach as working out how much material is left on a stick after several cuts, or how long a run of trim needs to be once a doorway is subtracted out.
Splitting a board into equal parts
Add your total length to the list, tap Go advanced, switch to Divide, and enter how many equal parts you need — for evenly spaced fence pickets, shelf pins, or baluster spacing. The calculator returns the length of each part and a full list of marks to make from one end of the board.
What you get
| Output | Example |
|---|---|
| Running total | 7' 5-3/8" |
| Decimal inches | 89.375" |
| Millimetres | 2270.1 mm |
| Ruler mark | between 5" and 6", at 3/8" |
| Divide into 3 parts | 2' 5-1/8" each, 2 marks |
Common uses
Totaling a cut list of studs or trim, working out an offcut after subtracting a piece, converting a tape reading to decimal for a CNC or CAD program, and evenly spacing marks along a board or wall. For pricing hardwood by the piece once you know the dimensions, use the Board Foot Calculator; for a floor or wall area, the Flooring Calculator.
Common questions
How do I add fractions on a tape measure?
Enter the feet, inches and the fraction of an inch for each measurement, keep Direction on Add, and tap Add to list. Each entry joins a running total shown in feet-inches-fraction, decimal inches and millimetres, rounded to the precision you pick.
How do I subtract a measurement?
Switch Direction to Subtract before tapping Add to list. The entry is subtracted from the running total instead of added, so you can work out an offcut length or the gap left after removing a piece.
What precision should I round to?
Most tape measures mark down to 1/16 inch, which is the default. Use 1/8 for rough framing work, or 1/32 or 1/64 for fine woodworking and joinery where the extra precision matters.
How do I split a board into equal parts?
Add your total length to the list, tap Go advanced, choose Divide into equal parts, and enter how many parts you need. The calculator shows the length of each part and every mark to make along the board.
Why does the ruler show a different mark than my exact fraction?
The ruler always displays the nearest 1/16 inch tick, since that's what a standard tape measure shows. The number above the marker is your exact result at the precision you chose, even if that's finer than 1/16.