Calculated result
15ft
Diagonal
Formula
UTIL-345-001diagonal = √(A² + B²)
12 ft
Side A
9 ft
Side B
1 yes=1
3-4-5 scaled
Utilities calculator
3-4-5 square calculator
3-4-5 square calculator publishes formula UTIL-345-001 version 1.0.0.
By Feroz Shiekh · Formula UTIL-345-001 v1.0.0 · Internal QA complete · Planning only — not a supplier quote
Formula
UTIL-345-001v1.0.0Project inputs
Enter field measurements. Imperial lengths take feet and inches. Unit conversion happens before the reviewed formula is applied.
All values can be refined when you edit the estimate. This tool does not replace field verification or local requirements.
3-4-5 square calculator publishes formula UTIL-345-001 version 1.0.0. 3-4-5 check square calculator for the diagonal of a rectangle so a layout can be squared in the field. Waste, rounding and the rate you type stay on the sheet so a quote letter can still explain the number. Add the line to an estimate. Planning takeoff only — not a code approval and not a live supplier price.
- Formula UTIL-345-001 version 1.0.0 is the arithmetic on this 3-4-5 square calculator page and on the quote letter.
- Utilities takeoff: Diagonal of a rectangle so a layout can be squared in the field. Planning geometry only. Waste and purchase rounding stay visible inputs, not hidden constants.
- Add the 3-4-5 square calculator result to an estimate, then send a quote letter — an old letter still explains itself.
- You type the unit rate. Construclytic does not fetch supplier prices for this utilities tool.
- Planning takeoff only. The 3-4-5 square calculator is not a code approval, mix design, or PE stamp.
Transparent cost view
Geometry pages start at zero. Add a planning rate only if you are pricing a related line. Pick a currency — badges, inputs, and totals follow.
This page is geometry, not a material takeoff. Leave rates at zero unless you are pricing a related line. Construclytic does not fetch supplier prices.
How this calculator works
A transparent 3-4-5 check square takeoff.
Feroz ShiekhWritten by Feroz Shiekh · founder
Diagonal equals √(A² + B²). A 3-4-5 layout is the same triangle scaled. Planning geometry only — not a survey.
UTIL-345-001 is the diagonal of a rectangle: √(A² + B²). A 12 and 9 layout is a 3-4-5 scaled by 3, so the diagonal is 15. Both diagonals of a rectangle must match before you pour or frame. Planning geometry only — not a survey.
Worked example. Example: sides 12 ft and 9 ft return a 15 ft diagonal, which is a 3-4-5 scaled by 3.
- 1. Pull A and B along the two walls or form boards.
- 2. The diagonal must match before you pour or frame.
- 3. Split odd rooms into rectangles and check each one.
Field notes that change the number
- Pull A and B along the two walls or form boards.
- The diagonal must match before you pour or frame.
- Split odd rooms into rectangles and check each one.
Common mistakes
- Treating a short diagonal as close enough and pouring anyway.
- Calling this a survey or a property-line check.
- Mixing metres and feet on the two sides.
Need the broader workflow? Read the utilities planning guide.
Questions
Questions about 3-4-5 check square
What if the diagonal is short?
The corner is not square. Kick a wall until both diagonals of a rectangle match.
Is this a survey?
No. Tape and a calculator. Hire a survey when the property line matters.
What is the formula ID?
This 3-4-5 square calculator publishes formula UTIL-345-001, version 1.0.0. The ID stays on the result and on the estimate line.
Is this engineering advice?
No. The 3-4-5 square calculator is a planning takeoff. Construclytic is not a registered engineering or contracting firm. Field checks, codes and product data still sit with you.
Does Construclytic fetch live supplier prices?
No. Costs on the 3-4-5 square calculator use the rate you enter. Construclytic does not fetch live supplier prices.