Construction calculators
that actually work.
Accurate material estimates for concrete, framing, roofing, excavation, masonry, and more. Built for contractors and serious DIYers.
Popular calculators
Most-used tools by contractors and DIYers
Concrete Slab Calculator
Calculate exactly how much concrete you need for any slab. Enter length, width, and thickness to get cubic yards, cubic feet, and cubic meters instantly.
Open calculatorGravel Calculator
Calculate how much gravel you need for driveways, paths, and landscaping. Get cubic yards, cubic feet, cubic meters, and tons of gravel instantly.
Open calculatorMulch Calculator
Calculate how much mulch you need for garden beds and landscaping. Get cubic yards, cubic feet, cubic meters, and bags of mulch for any area.
Open calculatorSand Calculator
Calculate how much sand you need for leveling, paver bases, sandboxes, and construction. Get cubic yards, cubic feet, cubic meters, and tons of sand instantly.
Open calculatorFence Post Calculator
Calculate how many fence posts you need, post hole count, recommended post depth, and number of fence sections. Supports any fence length and post spacing.
Open calculatorDeck Footing Calculator
Calculate how many deck footings you need, concrete volume per hole, total cubic yards, and bags of concrete. Supports any deck size, footing spacing, diameter, and depth.
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Every trade, every material
Construction formula reference
The six most common calculations — click any to open the full calculator
Why professionals use ConstructCalc
Built for the job site, not the classroom
Contractor-grade formulas
Industry-standard calculations with built-in waste factors. Same math used by professionals on every project.
Imperial & metric, one click
Switch unit systems without re-entering a single number. Results update instantly.
No account, no waiting
Open a calculator, enter dimensions, get your answer. No email, no signup, no friction.
Cost estimates built in
Enter your local material price to get a budget estimate alongside every volume calculation.
Step-by-step formulas
Every calculator shows exactly how the math works — verify any result against your own calculations.
Formulas explained
Common project questions answered alongside each calculator — standards, bag counts, and code requirements.
Construction guides & articles
How-to guides, cost breakdowns, and formula walkthroughs
Asphalt vs. Concrete Driveway: Cost, Pros, and Cons
Full comparison of asphalt vs. concrete driveways — upfront cost, lifespan, maintenance, climate performance, and resale value.
Read → deckingDeck Footing Calculator Guide: How Many Footings and How Deep
How to calculate deck footing sizes, spacing, depth, and concrete volume. Includes IRC tables and soil bearing capacity basics.
Read → framingDrywall Calculator Guide: How Many Sheets Do You Need?
Calculate drywall sheets for any room — walls, ceilings, and odd shapes. Includes waste factors, panel sizes, and ordering tips.
Read → fencingFence Post Calculator: Spacing, Depth, and Concrete Guide
How to calculate fence post count, spacing, hole depth, and concrete volume for any fence project. IRC guidelines included.
Read → landscapingHow to Calculate How Much Mulch You Need
Calculate mulch quantity for garden beds and landscaping. Coverage charts, depth recommendations, and buying tips.
Read → masonryPaver Base Calculator: How to Build a Stable Paver Patio
How much gravel and sand for a paver patio or walkway. Calculator guide, base depth requirements, and installation tips.
Read →Built on industry standards
Our formulas follow the same references used by engineers and contractors
American Concrete Institute — concrete volume and mix design
International Residential Code — footing depth, stud spacing, rafter spans
National Roofing Contractors Association — roofing material estimating
Portland Cement Association — concrete mix ratios and curing standards
ASTM International — material weight and density standards
Western Wood Products Association — lumber sizing and span tables
Frequently asked questions
How much concrete do I need for a 10×10 slab at 4 inches thick?
A 10×10 slab at 4 inches thick requires about 1.23 cubic yards before waste. With a 10% waste allowance, that is about 1.35 cubic yards, or roughly 62 bags of 80 lb concrete mix. Use the concrete slab calculator to adjust for any dimensions.
How many bags of concrete do I need per post hole?
A standard 10-inch diameter hole 3 feet deep takes about half an 80 lb bag. For a 6-inch diameter hole at 2 feet deep, one 40 lb bag per hole is usually sufficient. Hole diameter and depth are the main variables — the post hole calculator handles both.
What waste factor should I use for roofing shingles?
Use 10% for simple gable roofs and 15% for hip roofs, multi-valley roofs, or pitches above 8:12. Always round up to whole squares when ordering — a partial square costs the same to deliver.
How do I calculate the number of studs for a wall?
Divide wall length in inches by stud spacing (16 or 24 inches) and add 1 for the end stud. Add 3 studs per corner assembly and 4 studs per opening (2 king + 2 jack studs). The stud calculator handles all of this automatically.
Are these calculators accurate enough for contractor use?
Yes. Our formulas follow ACI, IRC, and NRCA industry standards — the same references used by engineers and estimators. Results are material estimates; always verify critical quantities with your supplier and add appropriate waste factors for your specific conditions.
Start calculating your project today.
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