Construction calculators that show their working
Free calculators for concrete, roofing and carpentry — every one built on the same verified engine, with its sources on the page.
Trades
Most used calculators
Square Footage
Area of rooms and surfaces
Feet & Inches
Add and subtract tape measurements
Cubic Yard
Volume for ordering material
Area
Multi-shape area with waste
Concrete
Volume for any pour shape
Concrete Slab
Volume, bags and weight for a slab
Concrete Bags
Bag counts by product and size
Footing
Continuous and pad footings
How these numbers are made
- Every figure is labelled: calculated, code reference, manufacturer specification, suggested default or assumption.
- Reference checks name the standard and edition they checked against, and say what they did not check.
- Nothing is hidden inside the number — the sources and assumptions are on the page, not behind a link.