CreteGenie — Concrete Calculators

Length (ft)

Width (ft)

Thickness (in)

Waste %

Concrete needed

—

cubic yards (with waste)

80 lb bags

—

or buy ready-mix

60 lb bags

—

smaller, more of them

Length × width × (thickness ÷ 12) ÷ 27 = cubic yards, then waste added. Typical: 4″ patios & walkways, 5″ light driveways, 6″ driveways & garages.

Total length (ft)

Width (in)

Depth (in)

Waste %

Concrete needed

—

cubic yards (with waste)

80 lb bags

—

or order ready-mix

60 lb bags

—

smaller, more of them

Continuous strip footing: total length × width × depth. Typical house footings run 16–20″ wide and 8″+ deep — check your local frost depth and plans.

Tube diameter (in)

Height each (ft)

How many

Waste %

Concrete needed

—

cubic yards, all tubes

80 lb bags

—

total for the job

Per tube

—

cubic yards each

Round form tubes (Sonotube®), piers & columns: π × radius² × height, times the count. Add a little extra at the bottom for belling or overflow.

Number of steps

Rise each (in)

Run each (in)

Width (ft)

Concrete needed

—

cubic yards (solid, +10% waste)

80 lb bags

—

or order ready-mix

60 lb bags

—

smaller, more of them

Solid poured steps, stacked like a staircase. A standard outdoor step is ~7″ rise and ~11″ run. Open or hollow steps use less — this is the solid-fill amount.

Length (ft)

Height (ft)

Thickness (in)

Waste %

Concrete needed

—

cubic yards (with waste)

80 lb bags

—

or order ready-mix

60 lb bags

—

smaller, more of them

Foundation & retaining walls: length × height × thickness. Walls are almost always a ready-mix job once you pass a yard — bags are a lot of mixing.

Length (ft)

Width (ft)

Base depth (in)

Loose volume

—

cubic yards

Weight

—

tons (approx)

Compacted depth

—

after tamping ~15%

Crushed stone base ≈ 1.4 tons per cubic yard. Order a little extra — gravel compacts ~15% when tamped, so loose volume is what you buy.

Length (ft)

Width (ft)

Grid spacing (in)

Edge clearance (in)

Stick length (ft)

Lap splice (in)

Bars lengthwise

—

running the length

Bars widthwise

—

running the width

Lap overlap

—

linear feet

Total rebar

—

linear feet (incl. laps)

A grid both directions at your spacing. 18″ on center is common for slabs & driveways; 12″ for heavier loads. Lap splice overlap is included automatically wherever a run is longer than your stick length (24″ ≈ 40× bar diameter for #4 bar).

Cubic yards needed

Price per 80 lb bag ($)

Ready-mix per yard ($)

Delivery fee ($)

Bags route

—

— × 80 lb bags

Ready-mix route

—

mix + delivery

—

Bags win on small jobs (under ~½ yard); past about a yard, ready-mix is usually cheaper once your time and labor count. Use your real local prices.