20 calculatorsMaterials, area, and energy
Home & Construction
Home and construction calculators estimate how much material a project needs before you buy: concrete, gravel, mulch, mortar, and bricks; paint, wallpaper, tile, flooring, and drywall; roofing, fences, and stairs. Others size an air conditioner in BTU, estimate pool volume, solar panels, or an appliance's electricity cost. Each explains its formula and assumptions. Add a margin for waste and check local codes for larger jobs.
- Roofing Calculator Free roofing calculator: enter the footprint in feet, the pitch (x/12) and overhang to get roof area in sq ft, roofing squares and shingle bundles to buy.
- Concrete Calculator Concrete calculator for slabs, footings and posts: get cubic yards and how many 40, 60 or 80-lb bags to buy, or the cement, sand and gravel to mix by hand.
- Electricity Cost Calculator Electricity cost calculator: see what any appliance costs per day, month and year from its watts and hours of use, or price your monthly kWh at your rate.
- Paint Calculator Paint calculator: enter room size, doors, windows and coats to see how many gallons of wall paint to buy, with ceiling option and your can's coverage rate.
- Tile Calculator Tile calculator: enter the floor or wall size, tile size, grout joint and waste to see how many tiles and boxes you need, plus the square footage to order.
- Wallpaper Calculator Wallpaper calculator: enter room size, doors, windows, roll size and pattern repeat to see how many strips and double rolls of wallpaper you need to order.
- Flooring Calculator Flooring calculator: enter room size, waste and box coverage to see how many boxes of laminate, vinyl plank or engineered wood to buy and the cost.
- Square Footage Calculator Square footage calculator for rectangles, L-shaped rooms, circles, triangles and trapezoids: get sq ft, sq yd and m², the perimeter and the cost per sq ft.
- Air Conditioner BTU Calculator Air conditioner BTU calculator: enter square footage, sun exposure and occupants to see the BTU/h a window or portable AC needs, per the ENERGY STAR chart.
- Mortar Calculator Mortar calculator: enter area, thickness and cement-to-sand ratio to see how many 94-lb bags of cement and how much sand you need for stucco or masonry.
- Brick Calculator Brick calculator: find how many bricks you need for a wall from its size, door and window openings, brick dimensions and mortar joint, with waste and cost.
- Solar Panel Calculator Solar panel calculator: estimate the system size in kW, number of panels, roof area, yearly production, savings and simple payback from your electric bill.
- Gravel Calculator Gravel calculator: enter length, width or diameter and depth to estimate cubic yards, tons and bags of gravel, crushed stone, sand or topsoil.
- Fence Calculator Fence calculator: enter up to four sides, post spacing, height and gates to estimate posts, rails, boards or panels and concrete bags for the posts.
- Drywall Calculator Drywall calculator: enter room size, doors and windows to estimate 4×8, 4×10 or 4×12 sheets, joint compound, tape and screws, with waste and ceiling.
- Mulch Calculator Mulch calculator: enter bed size and depth to see how many cubic yards of bulk mulch or 2 or 3 cu ft bags to buy, with a recommended-depth check.
- Stair Calculator Stair calculator: enter total rise and tread depth to get risers, riser height to 1/16 in, total run, stringer length and the IRC limits checked.
- Pool Volume Calculator Pool volume calculator: enter shape and depth for rectangle, round, oval or kidney pools to get gallons, liters and how long a hose takes to fill it.
- Ohm's Law Calculator Ohm's law calculator: enter any two of voltage, current, resistance and power to get the other two, with mV to kV, mA, kΩ and MΩ units and all 12 formulas.
- How Much Rent Can I Afford? How much rent can I afford? Compare the 30% rule, the 40× rent landlord test and 50/30/20 with your income, utilities and debts; check a candidate rent.