About Pour & Pave

Who We Are

Pour & Pave is a small independent site. We build the calculators, look up the numbers and fix them when they’re wrong. We don’t sell concrete, stone or mulch, and no brand or store pays us to mention them.

The calculators are free, with no sign-up.

Questions, or found a mistake? Email hello@pourandpave.com.

How the Calculators Work

Each calculator works in three steps. It turns your measurements into a volume, adds any extra you ask for, then converts that volume into what you actually order: cubic yards, tons, bags and a rough cost.

1. Volume

Every size is converted to feet first, so each size can be in its own unit: inches, feet or yards, or centimeters and meters in metric. Then:

Slab, footing, wall
  L × W × T
Column, circle
  π × r² × H
Ring
  π × (R² − r²) × H
Post hole
  (π × r² − post) × depth
Steps
  W × rise × run ×
  (1 + 2 + … + n)
By area
  area × depth

Here r is the radius (half the diameter) and R is the outer radius of a ring. For a post hole we subtract the part of the post that sits below grade, using actual lumber sizes: a 4×4 is really 3 1/2″ square, a 6×6 is 5 1/2″. Steps are figured as solid stairs, each step one rise taller than the one below. If you enter a top step depth, the top step uses it instead of the run.

2. Extra for waste

The concrete calculator adds 10% by default. The National Ready Mixed Concrete Association recommends 4% to 10% over plan for spills, over-excavation and uneven grade. The gravel and mulch calculators add nothing by default. If you want a cushion, type your own percentage.

3. What you buy

Cubic yards = cu ft ÷ 27
Tons = cu yd × tons/cu yd
Bags = cu ft ÷ bag yield,
  rounded up
Cost = quantity × price

Tons are US short tons of 2,000 lb. Metric results use exact factors: 1 ft = 0.3048 m, 1 lb = 0.45359237 kg.

Ready-mix plants charge a short-load fee when you order less than a full truck. Under 10 cubic yards, the calculator adds $53 per yard to your price (HomeGuide’s national figure, Jan 6, 2026).

The post hole tips follow Quikrete’s rule: dig the hole 3 times as wide as the post and one third as deep as the post is long, then add 6″ of gravel in the bottom.

The Numbers and Their Sources

Where we can, we take each number from the people who make or test the material: manufacturer data sheets, quarries, state and federal agencies and university extension services. Prices come from national cost guides and store listings, each with its date. These tables are built from the same data file the calculators use, so the two always match. Last reviewed Oct 27, 2026.

Concrete bag yields

Quikrete Concrete Mix No. 1101 and Sakrete High-Strength. Yield is how much mixed concrete one bag makes, per the maker’s data sheet. “Per cu yd” is how many bags make one cubic yard, rounded up. Sources: Quikrete Concrete Mix data sheet, Sakrete High-Strength data sheet.

For the weight line we take normal-weight concrete at 145 lb per cubic foot. Federal highway engineers put it at about 140⁠–⁠155 lb, a little heavier as the mix gets stronger (Federal Highway Administration).

Weight of stone, sand and soil

Crusher run is listed compacted. Topsoil is moist, the way it’s delivered. Stone varies from quarry to quarry, so on a big order ask your supplier what a yard of their material weighs. Mulch is sold by volume, so the calculator doesn’t weigh it. For reference, wood chips run about 500 lb per cubic yard (US EPA, Washington Dept. of Ecology). Sources: Vulcan Materials, Heidelberg Materials, Stoneco, HomeGuide (gravel), Graniterock, Illinois DOT, Quikrete Mason Sand, HomeGuide (sand).

Bag sizes

Sources: Home Depot (Earthgro mulch), Lowe’s (Sta-Green mulch), Ace Hardware (topsoil), Quikrete Mason Sand, Lowe’s (play sand), Lowe’s (all-purpose sand), Home Depot (pea gravel), Ace Hardware (paver base).

Default prices

National figures, before delivery and tax. Priced per cubic yard, gravel costs the same as per ton: price per ton × tons per yard. Cost guides update a few times a year, so some figures are more than a year old. Your local price may be far off, so type it in and the cost updates. Sources: Lowe’s (80-lb Quikrete), Lowe’s (60-lb Quikrete), Lowe’s (50-lb Quikrete), HomeGuide (concrete), HomeGuide (gravel), HomeGuide (sand), HomeGuide (mulch), Lowe’s (Sta-Green mulch), HomeGuide (topsoil), Ace Hardware (topsoil).

Typical depths

Sources: Quikrete sidewalk guide, Concrete Network, Penn State Extension (mulch), Clemson Extension, Morton Arboretum, Penn State Extension (lawns), NC State Extension, Belgard, Unilock.

What the Results Are and Aren’t

The results are estimates for ordering material, not an engineering design. Slab thickness, footing size and rebar depend on your soil, loads and local code, so check those with your building department or an engineer.

We left lava rock out because we couldn’t find a weight we trust. No producer publishes a weight for decomposed granite either, so that one is our estimate and the calculator says “about.”

Report a Wrong Number

If a number doesn’t match your data sheet, your yard’s scale ticket or a newer source, email hello@pourandpave.com. Tell us the page, the number and where yours comes from. We read every report, and when we change a number, the “Last reviewed” date above changes with it.

The Calculators

• Concrete calculatorCubic yards, 40- to 90-lb bags and cost for slabs, footings, post holes and steps.
• Gravel calculatorTons and cubic yards of gravel, crushed stone or sand for a base, driveway or path.
• Mulch & topsoil calculatorMulch or topsoil in cubic yards or bags for beds, lawns and raised beds.