Quick answer
- Enter each measurement with the Feet, Inch, and fraction keys.
- Use + or − exactly as you would on a standard calculator.
- Press = and read the simplified feet-inch-fraction result.
Inside the App
The workflow at a glance
This image is from the current Construction Pro project and shows the product interface behind this guide.
Step by Step
Add and Subtract Feet, Inches, and Fractions
Follow the sequence and keep units visible at every handoff.
Step 1
Set the precision first
Open Settings and choose the fraction precision used on the job: 1/8, 1/16, 1/32, or 1/64 inch. The calculator formats the final mark to that increment.
Step 2
Enter the first dimension
For 12 ft 7 3/8 in, enter 12, Feet, 7, Inch, then 3 and / and 8. The unit keys preserve the meaning of every part.
Step 3
Add or subtract the next dimension
Tap + or −, enter the second measurement the same way, and press =. There is no separate conversion to decimal inches.
Step 4
Check the tape-ready answer
For 12 ft 7 3/8 in + 5 ft 11 1/2 in, the result is 18 ft 6 7/8 in. The fraction is carried and simplified automatically.
Field Examples
Three practical checks
Example 1
Adding trim lengths
12 ft 7 3/8 in + 5 ft 11 1/2 in = 18 ft 6 7/8 in.
Example 2
Finding an offcut
16 ft − 9 ft 7 5/8 in = 6 ft 4 3/8 in.
Example 3
Repeating equal spacing
Divide a measured run by the number of equal spaces, then round only at the precision you will mark.
Common mistakes
What to verify
- Do not type 7.375 when you mean 7 3/8 in unless you deliberately chose decimal inches.
- Keep the Feet and Inch keys in each mixed measurement so the units stay unambiguous.
- Choose precision before copying the result to a cut list.
Related guides
Keep working
Can I use this result without checking it?
No. Confirm measurements, units, assumptions, and applicable code before cutting material, ordering supplies, or issuing a quote.
Does Construction Pro guess missing values?
No. Its calculators use explicit formulas and the inputs you provide; missing field conditions still require professional judgment.
Can I keep the calculation with a job?
Yes. Save verified calculations in a project and add a descriptive note so the crew can see what the result means.
Build Faster On Site
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