10 free calculators

Construction calculators that show their work.

Concrete, gravel, mulch, drywall, paint and more — instant material estimates with the formulas, conversion tables and answers behind every number.

Concrete & Masonry

Slabs, footings, columns and bag counts. The biggest cluster in the trades.

Concrete

Calculate how many cubic yards of concrete and how many 60 lb or 80 lb bags you need for a slab, patio or driveway.

Concrete Bags

Find out how many bags of pre-mixed concrete you need for a given volume, by bag size (40, 60 or 80 lb).

Square footage, cubic yards and the unit math behind every job.

Cubic Yards

Convert length, width and depth into cubic yards for concrete, soil, gravel, mulch or any bulk material.

Square Footage

Calculate the square footage of a room or area from its length and width, with optional quantity for multiple rooms.

Gravel, mulch, stone and topsoil by the yard or ton.

Gravel

Estimate how many cubic yards and tons of gravel you need for a driveway, path or drainage bed.

Mulch

Calculate how many cubic yards of bulk mulch or how many 2 ft³ bags you need to cover a garden bed.

Drywall, paint and lumber for interior work.

Board Feet

Calculate board feet of lumber from thickness, width and length, and price out a hardwood order.

Paint

Work out how many gallons of paint you need for a room based on wall area and number of coats.

Drywall

Estimate the number of drywall sheets, plus joint compound and screws, for a room's walls and ceiling.

Framing and exterior structures by the board, panel or square.

Fence

Estimate fence posts, rails and pickets from total fence length and post spacing.

How to Convert Cubic Feet to Cubic Yards

Divide cubic feet by 27 to get cubic yards. Here's why, with a conversion table for common volumes.

What Is a Cubic Yard?

A cubic yard is a volume 3 feet wide, 3 feet long and 3 feet tall — 27 cubic feet. Here's how to picture it.

How Many 80 lb Bags of Concrete Are in a Yard?

You need 45 × 80 lb bags to make one cubic yard of concrete. Here's the math and the counts for 60 and 40 lb bags too.

How Much Does a Bag of Concrete Weigh?

Concrete comes in 40, 50, 60 and 80 lb bags. The number on the bag is its dry weight before you add water.

How Thick Should a Concrete Slab Be?

4 inches is standard for patios and walkways; driveways need 5–6 inches. A thickness chart by application.

How Much Does Concrete Cost Per Yard?

Ready-mix concrete runs about $125–$165 per cubic yard delivered, before short-load and other fees.