Concrete Calculator

Bagged is mixed on site and ordered in bags. Ready-mix is delivered by the yard on a truck, so the order is stated in cubic yards.

LengthftWidthftDepthftWaste percent%Estimated: 5–10% for a simple slab, more for irregular forms. A jobsite allowance for over-excavation, subgrade that is out of level and what stays in the truck — not a published figure.

Cement partsoptionalpartsHow many parts cement, e.g. 1 in a 1:2:4 mix.Sand partsoptionalpartsHow many parts sand, e.g. 2 in a 1:2:4 mix.Gravel partsoptionalpartsHow many parts gravel, e.g. 4 in a 1:2:4 mix.

Reinforcement typeNot assumedA rebar grid and welded wire mesh are different orders entirely. Mesh is the usual choice on a residential slab.Rebar spacingoptionalftRebar bar sizeASTM A615Rebar chair spacingoptionalftSpacing of the chairs holding the grid off the subgrade. 4 ft if left blank — a practice figure, not a code requirement. Tighten it for heavier bar.Ties per intersectionoptionaltiesWire ties where the bars cross. 1 if left blank -- an estimated jobsite practice figure for an average slab, not a code requirement.

Order — cu yd of concrete for this pour — — 80 lb bags.

Order

Concrete estimate

Warnings

ERROR Enter a depth greater than zero.
ERROR Length and width are required for rectangular pours.
INFO Material estimate only. Footing depth, size, reinforcement, frost depth, and bearing capacity must be verified locally.

Detail values

Cubic feet: —
Cubic yards: —
Waste-adjusted cubic yards: —
Effective depth (incl. frost line): — ft

Assumptions

Supply method: Bagged mix, mixed on site
Bag yield: 0.6 cu ft per 80 lb bag (check the bag)
Reinforcement: not entered -- no reinforcement counted

Included: concrete volume, waste allowance.

Not included: labor, delivery, permits, disposal, compaction (enter your intended post-compaction depth/volume — this estimate does not account for compaction itself), reinforcement (no type selected) and forms.

Formula details

Rectangular volume: length x width x depth
Round volume: pi x radius^2 x depth
Cubic yards: cubicFeet / 27

Material List

About this calculator

Switch between rectangular and round pours, add waste, and optionally convert the result into 60 lb or 80 lb bag counts.

FAQ

Can I estimate sonotube piers here?

Yes. Use the round mode, enter diameter and depth, and the calculator returns cubic feet, yards, and optional bag counts.

Why is there a local verification warning?

Concrete quantity alone does not verify footing design, reinforcement, frost depth, or bearing capacity.

Are bag counts based on waste-adjusted volume?

Yes. The bag estimate uses the waste-adjusted cubic-yard total before rounding up to full bags.

Disclaimer

Material estimate only. Footing depth, size, reinforcement, frost depth, and bearing capacity must be verified locally.

Pour shape

Dimensions

Mix ratio

Reinforcement