How much do you really need?

Concrete, gravel, mulch, roofing and more. Enter your measurements and see the amount of material with every step of the math shown.

Concrete & Masonry

Concrete Calculator Find how many cubic yards of concrete or how many bags you need for a slab, footing, wall or column.
Brick Calculator Find how many bricks you need for a wall, minus doors and windows, with mortar joints and waste.
Concrete Block Calculator Count the concrete blocks for a wall by its length and height, minus doors and windows, with mortar and grout.
Paver Calculator Estimate the pavers, base gravel and bedding sand for a patio or walkway.
Retaining Wall Calculator Blocks, caps and base stone for a block retaining wall. Counts pieces, no design.
Cement Calculator Find how many 94 lb bags of portland cement, plus sand and gravel, you need for a slab or any concrete volume.
Concrete Footing Calculator Add strip, pad and round footings to get cubic yards of concrete and the number of 40, 60 and 80 lb bags.
Sonotube Calculator Pick a Sonotube diameter and height to get the concrete in cubic yards and bags, with an optional pad.
Post Hole Concrete Calculator Find the concrete and bags of Fast-Setting or Concrete Mix for post holes, with the post volume subtracted.
Rebar Calculator Count rebar bars, feet and weight for a slab from size, spacing and edge clearance.
Self Leveling Concrete Calculator Bags of self leveling concrete for a floor by area and thickness, using manufacturer coverage.
Mortar Calculator Bags of mortar mix for a brick or block wall, repointing or stone, from maker yields.

Yard & Paving

Roofing & Siding

Decks & Framing

Interior

Measuring & Pool

Electrical & HVAC

Which calculator you need for your project

Calcs24 has 80 free construction and DIY calculators for the jobs people plan most at home: pouring concrete, covering a yard, replacing a roof, building a deck or a fence, finishing a floor or a room, and sizing heating, cooling and electrical work. If you are not sure where to start, find your project below.

Pouring a slab, a footing or a post

Start with the concrete calculator. It turns the size of a slab, a footing, a wall or a column into cubic yards for a ready-mix order, or into 40, 60 or 80 lb bags if you mix it yourself. Most slabs also need a compacted base under them, and the gravel calculator gives you that base in cubic yards and tons. For walls, use the concrete block calculator or the brick calculator, which also estimate the mortar.

For footings there is the concrete footing calculator, which adds strip, pad and round footings in one list, the Sonotube calculator for round forms and the post hole concrete calculator, which takes off the volume of the post. If you mix concrete from scratch, the cement calculator gives bags of portland cement plus the sand and gravel, and the rebar calculator counts the bars for a slab. For brick and block work the mortar calculator counts bags of preblended mortar, and the retaining wall calculator counts the blocks, caps and base stone of a block wall.

Driveways, paths and the yard

Loose materials are sold by the cubic yard or by the ton, so the calculators for gravel, mulch, topsoil and dirt give you both whenever a weight makes sense. If your supplier quotes in tons and you think in yards, the tons to cubic yards calculator converts one into the other for the material you choose. For a new lawn there is the sod calculator, and for hard surfaces the paver and asphalt calculators.

When you already know the material, each one has its own calculator with its own sources: stone, crushed stone (with compaction), pea gravel, river rock, landscape rock, decomposed granite, sand and compost. For the lawn and the garden, the grass seed and lawn fertilizer calculators use rates published by university extension services, and the plant spacing calculator counts how many plants fit a bed. To turn the size of a lot into acres, use the acreage calculator.

Roofing and siding

The roofing calculator takes the footprint of the house and the pitch of the roof and gives you the real roof area in squares and the number of shingle bundles. If you do not know the pitch, measure the rise and the run and use the roof pitch calculator first. The siding calculator works out the wall area, takes off doors and windows and adds the waste you choose.

The shingle calculator adds starter strip and ridge cap bundles, the metal roofing calculator counts panels instead of shingles, and for the frame there are the roof truss and rafter length calculators.

Decks, fences and stairs

The deck calculator counts deck boards and screws from the real board width, the gap and the joist spacing, the fence calculator counts posts, rails and pickets for the length of your fence, and the stair calculator works out the number of steps, the riser height and the tread depth and checks them against the limits of the International Residential Code. To price lumber, the board foot calculator turns your cut list into board feet.

For a wall, the framing calculator counts studs, plates and headers, and the lumber calculator turns a list of pieces into the boards to buy. The stair stringer calculator gives the shortest board for a stringer, and the stain calculator works out the gallons for a deck or a fence. The linear feet calculator adds up lengths of any trim or board.

Painting, floors, tile and insulation

For a room, measure the walls once and use the paint calculator for gallons, the drywall calculator for sheets, the tile calculator for tiles and boxes and the wallpaper calculator for rolls. The paint, drywall and wallpaper calculators let you take off doors and windows, so you do not pay for material that would cover an opening.

For floors there are the flooring, laminate, hardwood, vinyl plank and carpet calculators, and for tile work the thinset and grout calculators. The self leveling concrete and epoxy calculators cover floor preparation and coatings, the baseboard and wainscoting calculators the trim, and the insulation and spray foam insulation calculators the walls and the attic.

Measuring and pools

When you just need the size of something, the square footage, cubic yard and cubic feet calculators add up rooms and shapes in any mix of feet and inches. The pool volume calculator gives you the gallons in a pool, and the pool salt and pool chlorine calculators use that volume with figures from the equipment makers and state health departments.

Electrical, heating and cooling

The Ohm’s law, watts to amps, kVA and power factor calculators cover the basic electrical math. The voltage drop, breaker size and electrical load calculators name the published sources they follow. All of them give estimates, and a licensed electrician and your local code have the last word. For heating and cooling, the BTU and AC size calculators follow the ENERGY STAR room air conditioner chart, and the generator size and water heater size calculators add up what your home needs.

Why these calculators and not others

Many online calculators give you one number and nothing else. These show every step of the math: what was measured, what was multiplied by what and where each figure comes from. You can follow it and check it yourself.

When a calculator uses data that depends on a product, such as how much one bag of concrete fills or how many bundles of shingles cover a square, it says which manufacturer or standard the figure comes from and when it was checked. Those values are always editable, because another brand may be different. Write in the number on your own bag or box and the result changes with it.

How we check that the math is right

A calculator that gets it wrong is worse than none, because you trust it. This is what every calculator goes through before it is published:

Every figure comes from a source we opened. If a number could not be checked in a manufacturer document, a published standard or an official source, it was left out.
The formulas are tested with worked cases. The expected results are worked out separately and compared with what the calculator returns, including small values and mixed units.
A second, independent review. Each calculator is checked again, figure by figure and sentence by sentence, before it goes live.

Each calculator page also includes a worked example taken from the calculator itself, so you can enter the same numbers and see the same result.

Key numbers at a glance

These are some of the figures the calculators use. The definitions are exact. The product figures are the ones published by the source next to them, checked in October 2026.

Figure	Value	Source
One cubic yard	27 cubic feet	Definition
One short ton, the ton used in the US	2,000 lb	Definition
Yield of an 80 lb bag of concrete mix	About 0.60 cu ft	Quikrete 1101 data sheet
Yield of a 40 lb bag of concrete mix	About 0.30 cu ft	Quikrete 1101 data sheet
One roofing square	100 sq ft of roof	GAF
Bundles of standard asphalt shingles per square	Usually 3	GAF
Coverage of one gallon of paint, one coat	About 350 to 400 sq ft	Sherwin-Williams
One 4 × 8 ft sheet of drywall	32 sq ft	Gypsum Association GA-223

Always plan for a little extra

A calculator gives you the amount that fills the space you measured. Real jobs lose some material to cuts, breakage, uneven ground and spills, which is why many of the calculators let you add a waste percentage. When in doubt, check the quantity with your supplier before you order.

Your numbers stay in your browser

All the math runs on your own device. The measurements you type are not sent to our server, saved or recorded anywhere. You do not have to take our word for it: once a page has loaded, you can disconnect from the internet and the calculator keeps working.

Frequently asked questions

Are these calculators free?

Yes, all of them. There is nothing to sign up for, no email to give and nothing to install. You open a calculator and use it.

Where do the numbers come from?

Material data, such as bag yields, coverage rates and standard sizes, comes from manufacturers and published standards. Each calculator that relies on such data names its source, so you can check it yourself.

Is what I type saved anywhere?

No. The math runs in your own browser, so the measurements you enter are never sent to a server.

Can I use the result to order materials?

Use it as an estimate. Real needs vary by product, site conditions and waste, so confirm quantities with your supplier or a qualified professional before you buy.

Do the calculators work on a phone?

Yes. They are built to be used with a thumb and fit the phone screen without zooming or side scrolling.