Concrete and masonry calculators

Which concrete or masonry calculator do I need?

Start from the shape you are filling or building. Anything poured into a flat form, a trench or a tube goes through the concrete volume and bag count tool, which switches between slab, footing and round-column modes. Posts set in fast-setting mix are a different job, because that mix is poured dry into the hole and its makers publish per-hole charts. Walls built from units, rather than poured, need a count of blocks and a count of mortar bags, which are two separate steps.

The table matches common projects to the calculator that answers them and says what you get back. Calculators not yet published appear as plain text; they follow the same method when they go live.

Concrete and masonry pages

What numbers do concrete estimates rest on?

Every concrete estimate is a volume divided by what one bag or one truckload delivers. One cubic yard is 27 cubic feet (National Institute of Standards and Technology and UK Parliament (legislation.gov.uk)). One cubic yard equals about 0.765 cubic metres. US premix bags are sold by weight, but what matters is the yield printed on the bag, and the three common sizes make far less than most people guess. About 45 bags of 80 lb concrete make one cubic yard (before waste).

UK and EU bags differ again. A bag of Blue Circle ready-to-use concrete makes about 0.01 m³, so roughly 100 bags per m³. German dry mixes are quoted per kilogram instead. Because the bag sizes and yields differ by market, the calculators here use each product's published yield rather than converting one bag size into another by weight.

How thick does code say a slab and footing must be?

The US model code sets a lower minimum than most people expect. The IRC requires concrete slab-on-ground floors in homes to be at least 3 1/2 in (89 mm) thick. The widely repeated 4 in rule comes from manufacturers' advice for walks and patios and from the base course, not from the slab minimum (International Code Council / California Building Standards Commission via GoCodebook and UpCodes (Colorado DFPC Residential Code 2021, based on 2021 IRC)). IRC concrete footings must be at least 12 in (305 mm) wide and 6 in (152 mm) deep. Exterior footings must sit at least 12 in below undisturbed ground, and below the local frost line.

Bagged mixes have their own floor. Standard and fast-setting bagged concrete mixes are meant for pours 2 in (50 mm) thick or more. Strength matters as much as thickness for outdoor work. The IRC sets a minimum compressive strength by location and weathering exposure. Where weathering is moderate or severe, exposed concrete must be air-entrained at 5-7% air. The table shows the code's minimums. A standard bagged mix from Quikrete or Sakrete is rated at 4,000 psi (27.5 MPa) at 28 days by its maker, which is above every value in the table. Air entrainment is a separate requirement, so for exposed work in a cold climate check that the mix you buy is air-entrained, or order air-entrained ready-mix.

How are block and mortar quantities worked out?

Block counts come from the face area of the wall, not its thickness. 8 x 16 in blocks need 1.125 blocks per sq ft of wall (112.5 per 100 sq ft) before waste. Block count per wall area depends only on face size, so the same count applies to 6, 8, 10 or 12 in wide blocks. The National Concrete Masonry Association's planning figure already includes breakage: NCMA estimates 119 blocks per 100 sq ft (9.29 m²) of wall, including about 5% for waste and breakage. A nominal block is smaller than its name. A nominal 8 x 8 x 16 in block actually measures 7 5/8 x 7 5/8 x 15 5/8 in, leaving room for a 3/8 in joint. Quikrete describes the standard 8 x 8 x 16 in block as 200 x 200 x 405 mm.

Mortar is the step where published figures disagree most. One 80 lb bag of Quikrete Mortar Mix (Type N) lays up to 37 standard bricks or 13 standard 8 x 8 x 16 blocks. One 80 lb bag of Sakrete Type N Mortar Mix lays about 40 standard bricks or 15 8 in blocks with 3/8 in joints. NCMA estimates one 80 lb bag of preblended mortar lays about 16 conventional blocks or 50 brick-sized units. The spread comes from joint thickness, how fully the joints are filled and how much is dropped, so mortar waste allowances run high. Add 15-25% to net mortar quantities for waste. The mortar calculator shows the manufacturer figure it uses so you can match it to the bag you buy.

How much concrete and cement do the US, UK and EU use?

US cement use has held roughly level in the US Geological Survey's 2026 summary. USGS estimates US apparent cement consumption at 110 million metric tons in 2025, unchanged from 2024 and down from 114 million in 2022 (Mineral Commodity Summaries 2026). Domestic plants supply most of it: US portland, blended and masonry cement production was an estimated 84 million metric tons in 2025 from 97 plants in 34 states and Puerto Rico, down from 91 million in 2021 (USGS MCS 2026). Nearly all of that cement leaves the plant as ready-mix rather than in bags. An estimated 70% to 75% of US cement sales in 2025 went to ready-mixed concrete producers (USGS), and NRMCA's production model assumes 75% of shipped cement goes to ready mix.

The ready-mix industry's own count is in cubic yards. NRMCA estimates US ready-mixed concrete production at 379,149,000 cubic yards (289.9 million cubic meters) in 2024, down about 5% from 400,024,000 cubic yards in 2023. US ready-mixed concrete production for January-June 2025 was 172.8 million cubic yards, 5.3% below the same period of 2024, per NRMCA's monthly production sheet. Great Britain ready-mixed concrete deliveries were 11.03 million cubic meters (about 14.4 million cubic yards at 1.308 yd3 per m3) in 2025, down from 15.33 million in 2021, per DBT's September 2026 building materials bulletin. UK housebuilding accounted for 29% of ready-mixed concrete demand and 23% of aggregates demand in 2024, per the MPA Profile 2025. EU27 cement production was 160.8 million tonnes in 2024 (down 0.2%) while EU27 consumption fell to 148.1 million tonnes, per Cement Europe's 2025 Activity Report.

Concrete is also the largest item in demolition waste, and most of it is crushed for reuse. Concrete made up 405.2 million US tons (67.5%) of the 600 million tons of US construction and demolition debris in 2018, with 381 million tons from demolition; 2018 is still EPA's latest C&D estimate. In 2018, 301.2 million US tons of C&D concrete were sent to aggregate reuse and 71.2 million tons to landfill, per EPA's latest C&D estimate. Prices have risen sharply since 2020: US producer prices for ready-mix concrete were 38.6% above the 2020 average in September 2026 and 2.3% up on a year earlier (BLS PPI).

The data pages hold the full series behind these figures: cement production and consumption data, C&D debris figures by material and construction material price changes.

Where do these calculators stop?

They count material; they do not design structures. The concrete calculator gives the volume of a footing you have already sized, but it cannot tell you how wide that footing must be for your soil and load. Code footing tables by load and soil bearing were not part of the sourced data, so no calculator here claims to size a footing. Frost depth is set locally. Posts carrying structures such as decks should go at least 6 in (150 mm) below the frost line.

Reinforcement is another gap. Rebar weights and cover rules are sourced, but published guidance on rebar spacing in a residential slab was not found in a primary document, so the site does not suggest a bar spacing. If your plans or your building department specify rebar or mesh, follow them.

Finally, every figure assumes the product named in the sources. A bag from another maker can yield more or less, so check the printed yield and the calculator's assumptions list before you buy a large quantity.

How are the figures on these pages checked?

Each number on this page and in the calculators comes from a code, a standard, a government dataset or a manufacturer's data sheet, and each one is listed in the sources at the foot of the page. Where two sources disagree, as UK bag yields and mortar coverage do, both figures are shown and the calculator says which one it uses. Nothing was measured or tested by us. The full rules are on the formulas and data sources page, and the long-hand concrete calculation method shows every formula step by step. For choosing a mix, see the concrete mix ratio chart.

Brick walls and render sit with the wall and paint calculators, and decks, stairs and fence posts with the outdoor structure calculators.

Concrete and masonry questions