Construction Calculators
Free construction & DIY layout calculators with dimensioned diagrams and cut lists.
- Rafter CalculatorCommon rafter length, cut angles, diagram and cut list.Open calculator
- Roof Pitch CalculatorConvert rise & run to pitch ratio, degrees, percentage and a chart.Open calculator
- Cinder Block CalculatorEstimate blocks, mortar, and core-fill concrete for a wall — with a dimensioned diagram and cut list.Open calculator
Most online calculators give you a single number. These give you the whole job — a dimensioned diagram, the cut angles, and a printable cut list — so you know exactly what to measure, cut, and buy before you pick up a saw.
What every calculator gives you
A dimensioned diagram
Every measurement labeled on a clear, print-friendly drawing. Readable in plain black and white, with no color-coding to squint at.
A printable cut list
Quantities and cut lengths laid out ready for the lumber yard.
Math you can check
Every result comes from standard geometry, with the formula and its source shown, so you can trust the number before you cut.
Built for your phone
Mobile-first and fast. No app to install, no sign-up, completely free.
How it works
- 1
Enter your dimensions
Span, pitch, wall length — whatever the calculator needs.
- 2
Read the diagram and results
The geometry and angles update as you type.
- 3
Print or save the cut list
Take it to the yard or the job site.
Which calculator do you need?
Not sure where to start? Pick by the job in front of you.
Framing or measuring a roof
Use the rafter calculator for common rafter length, the plumb and seat cut angles, and a full cut list from your span and pitch. To convert a roof’s rise and run into a pitch ratio, degrees, a percentage or a 1-in-N gradient, use the roof pitch calculator.
Building a block wall
The cinder block calculator estimates how many blocks you need for a wall, the bags of mortar to lay them, and the concrete to fill the cores — with a dimensioned wall diagram and a course-by-course layout you can build from.
Frequently asked questions
- Are these construction calculators free to use?
- Yes. Every calculator is completely free, runs in your browser, and needs no sign-up and no app to install.
- How accurate are the results?
- Each result comes from standard geometry or published material coverage, and every page shows the formula and its source so you can check the number yourself. They are estimating tools, so always confirm critical dimensions and quantities against your actual materials and local building codes before you cut or buy.
- Do the calculators work in feet-inches and metric?
- Yes. On the calculators that use length units you can switch the display between imperial — feet, inches and fractions — and metric.
- Can I print or save the cut list?
- Yes. The dimensioned diagrams and cut lists are laid out to print cleanly in plain black and white, so you can take a paper copy to the lumber yard or the job site.
- Do these replace an engineer or a building permit?
- No. They help you plan a job and estimate materials, but they are not a substitute for a structural engineer, a licensed contractor, or your local permit and code requirements.
More calculators — roof pitch, concrete, blocks, rebar and stairs — are on the way.