One hub, four material calculators
Running short on material mid-job costs you a supply run; over-ordering eats your margin. Our free construction calculators hub puts four job-ready calculators in one place — concrete, drywall, paint and gravel — each with a waste factor built in. No signup, no paywall, imperial and metric.
How many sheets of drywall do I need?
Add up your wall and ceiling square footage, then divide by the sheet size: a 4×8 sheet covers 32 ft², a 4×10 covers 40 ft², a 4×12 covers 48 ft². A 12×12 room with 8 ft ceilings is about 384 ft² of wall plus 144 ft² of ceiling — roughly 17 sheets of 4×8 before openings. Pros add 10–15% waste for cuts around windows, doors and outlets.
The drywall calculator also counts what finishers forget to buy: about 1 lb of screws per 300 ft², one 4.5-gal bucket of joint compound per ~450 ft², and a 500 ft roll of tape per ~1,400 ft².
How much paint for a room?
One gallon of paint covers roughly 350 ft² per coat. Measure the wall perimeter, multiply by ceiling height, subtract about 20 ft² per door and 15 ft² per window, then multiply by your number of coats — two coats is the standard for a color change. A 12×12 room with 8 ft ceilings needs around 2 gallons for two coats.
The paint calculator handles doors, windows, ceilings and coats, and tells you the cheapest way to buy it — like "2 gallons + 1 quart" instead of a third gallon you'll never open.
How many tons of gravel?
Gravel is quoted by the cubic yard or by the ton. Length × width × depth (in feet) ÷ 27 gives cubic yards; most crushed stone weighs about 1.4 tons per yard. A 10×20 ft driveway topped at 3 in deep is ~1.9 yd³ ≈ 2.6 tons. Standard dump trucks haul 10–14 yd³, so the gravel calculator also estimates truck loads — and 0.5 ft³ bag counts for small jobs.
Concrete: yards and bag counts
For slabs, footings, columns and steps, the concrete calculator converts your pour to cubic yards and meters and tells you exactly how many 40, 60 or 80 lb bags to buy — about 45 × 80 lb bags per cubic yard. Over ~1 yd³, order ready-mix. Full breakdown in our concrete guide.
From material counts to a priced bid
Calculators tell you what to buy. If you're a contractor, ConstructHelp's AI Pricing tool takes it further — describe the job (or upload photos and blueprints) and get a Good/Better/Best estimate calibrated to your local market, with a material takeoff you can export as a branded PDF and send to your client as a one-tap proposal. The calculators are free forever; the pricing tool is where the bids get won.
