Concrete Calculator: Beam Volume

Quickly estimate concrete for rectangular beams. Enter beam length, width, and depth, add a waste allowance, and include optional deductions for through-holes or rectangular pockets. You will get per-beam and total volumes in m³, yd³, and ft³, plus approximate bag counts. Notes, formulas, and FAQs are included.

Units Metric (m, mm) US Customary (ft, in)

Beam length

Beam width

Beam depth

Number of beams

pcs

Waste allowance

Covers spillage and dimensional variation. Many projects add 4 to 10 percent.

Subtract common voids and block-outs (optional)

Through-hole diameter

Assumes a circular opening that passes fully across the beam width.

Number of through-holes per beam

pcs

Rectangular pocket length

Length along the beam axis.

Rectangular pocket width

Rectangular pocket depth

Number of pockets per beam

pcs

Results

Per-beam net volume

0.000 m³

0.000 yd³

0.00 ft³

Total net volume

0.000 m³

0.000 yd³

0.00 ft³

Total with waste

0.000 m³

0.000 yd³

0.00 ft³

Approximate bag counts (total with waste)

US bag sizes (QUIKRETE® yield)

40 lb bag00.30 ft³ per bag

50 lb bag00.375 ft³ per bag

60 lb bag00.45 ft³ per bag

80 lb bag00.60 ft³ per bag

90 lb bag00.675 ft³ per bag

Yields per bag from QUIKRETE data sheet. Actual yield varies with placement and compaction. Source

Metric bag sizes

Edit yields to match your local supplier data.

20 kg bag yield m³ 25 kg bag yield m³ 40 kg bag yield m³

20 kg bag0

25 kg bag0

40 kg bag0

How to use this concrete calculator

Select metric or US units.
Enter beam length in m or ft, width and depth in mm or in.
Set the number of identical beams to calculate a total.
Add a waste allowance. Many jobs add 4 to 10 percent.
Optionally subtract circular through-holes and rectangular pockets per beam.
Read per-beam and total volumes, then review bag counts for ordering.

Formulas and assumptions

Per-beam gross volume: V = L × B × H, where L is length, B is width, and H is depth. All are converted to meters internally, so volume is in m³.
Through-hole deduction (per hole): V_hole = π × (d/2)² × B, assuming a circular hole passing fully across the beam width.
Rectangular pocket deduction (per pocket): V_pocket = L_p × W_p × H_p.
Total net volume: V_total = (V − n_holeV_hole − n_pocketV_pocket) × n_beams, clipped at zero.
Waste: V_{with waste} = V_total × (1 + waste%).
Bag counts: bags = Required volume ÷ bag yield. US yields use ft³ per bag. Metric yields use m³ per bag and can be edited.
Scope: This calculator estimates concrete only. It does not size reinforcement, cover, or formwork.

References

Waste allowance of about 4 to 10 percent is common in practice (NRMCA CIP 8, NRMCA CIP 31).
US bag yields: QUIKRETE® Concrete Mix 1101 (data sheet).

FAQs

Does this account for rebar and cover?

No. It calculates concrete volume only. Reinforcement design, cover, and formwork should follow your engineer and local code.

Where should I place through-holes in beams?

Hole placement affects strength and deflection. Always follow your structural engineer. Avoid large holes near supports or at high shear zones.

Can I enter different beams at once?

This version assumes identical beams. For mixed sizes, run separate calculations or ask for a multi-line version.