Calculate the concrete volume required for one or more RCC beams from their width, depth, and length.
How to Use the Beam Calculator
Enter the beam cross-section width and depth in inches, and its length in feet.
Enter the number of identical beams.
Click "Calculate" to see the concrete volume per beam and in total.
Worked Example with the Default Values
The calculator opens with five beams of 9 × 12 inches, each 20 ft long. Width and depth are converted to feet first: 9 ÷ 12 = 0.75 ft and 12 ÷ 12 = 1 ft. One beam is 0.75 × 1 × 20 = 15.00 cu.ft, and five beams total 75.00 cu.ft.
Ready-mix suppliers in India usually quote and deliver in cubic metres. Divide cubic feet by 35.315: 75 cu.ft is about 2.12 m³.
Concrete per Running Foot for Common Beam Sizes
Width × depth (inches)
cu.ft per foot of length
cu.ft for 10 ft
m³ for 10 ft
9 × 12
0.75
7.50
0.21
9 × 15
0.94
9.38
0.27
9 × 18
1.13
11.25
0.32
12 × 18
1.50
15.00
0.42
12 × 24
2.00
20.00
0.57
A 9-inch width is common in houses because it matches a standard brick wall. These sizes are for quantity estimates only; the actual size of each beam must come from the structural drawings.
Measuring Beams Correctly
Length: take the clear length between the faces of the supporting columns if you are also calculating column concrete up to the beam soffit and above. Counting the junction in both places overstates the total.
Depth: when a beam is cast together with the roof slab, its top part is inside the slab. Estimators often take only the depth projecting below the slab for the beam and count the slab separately. Follow one convention consistently.
Group beams of the same size together. Run the calculator once for each size, such as plinth beams, lintel beams and roof beams, and add the totals.
From Volume to Cement, Sand and Aggregate
The volume shown is wet, compacted concrete. For site mixing, a common Indian estimating practice multiplies it by about 1.54 to get the dry volume of materials, then splits that dry volume by the mix ratio. For a nominal M20 mix of 1 : 1.5 : 3, the parts add to 5.5.
For the 2.12 m³ example: dry volume = 2.12 × 1.54 ≈ 3.27 m³. Cement = 3.27 ÷ 5.5 ≈ 0.59 m³, which at 1,440 kg per m³ is about 856 kg, or roughly 17 bags of 50 kg. Sand ≈ 0.89 m³ and 20 mm aggregate ≈ 1.78 m³. Add a small wastage allowance, and treat this as a budgeting figure; the mix used on site should follow the engineer's specification.
Frequently Asked Questions
Volume per beam (cu.ft) = (Width ÷ 12) × (Depth ÷ 12) × Length, since width and depth are entered in inches and length in feet. Multiply by the number of beams for the total.
No. This only estimates concrete volume. Reinforcement steel quantity depends entirely on structural design, so it must come from a qualified engineer's drawings, not a generic calculator.
Divide the cubic feet figure by 35.315, since one cubic metre is about 35.315 cu.ft. For example, 75 cu.ft is about 2.12 m³. Ready-mix concrete is normally ordered in cubic metres.
Only if you are not counting that part in the slab volume. For beams cast with the slab, a common approach is to measure the beam depth below the slab and calculate the full slab area separately, so no concrete is counted twice.
Group the beams that share the same width and depth, and enter the average length and count for each group. Calculate each group separately and add the totals together.