Isolated footing quantity calculation: excavation, PCC, RCC and steel (worked example)
Published 5 Oct 2026
To measure an isolated footing, work from the bottom up: excavation, PCC bed, RCC footing, column stub up to ground level, formwork, reinforcement, then backfilling. Each is length x breadth x depth. This guide works one example through for 12 footings and shows the totals you would carry into a BOQ.
The example
These dimensions are illustrative. Take real ones from your foundation plan and structural schedule.
| Item | Value |
|---|---|
| Number of footings | 12 |
| Footing size | 1.5 m x 1.5 m |
| Footing thickness (uniform) | 0.45 m |
| PCC bed | 1.7 m x 1.7 m x 0.10 m (100 mm projection each side) |
| Depth of excavation below ground level | 1.5 m |
| Column stub from footing top to ground level | 0.30 m x 0.30 m x 0.95 m |
| Footing steel | 12 mm bars at 150 mm c/c both ways, 50 mm cover |
Column stub length = 1.50 - 0.10 (PCC) - 0.45 (footing) = 0.95 m.
Step 1: Excavation
Volume = length x breadth x depth. Measure to the plan size of the PCC bed down to its underside.
Per footing: 1.7 x 1.7 x 1.5 = 4.335 m3. For 12: 52.02 m3.
Unless your specification or contract provides for working space or side slopes, do not add extra width. If it does, state that assumption on the measurement sheet.
Step 2: PCC bed
Per footing: 1.7 x 1.7 x 0.10 = 0.289 m3. For 12: 3.468 m3.
Step 3: RCC footing
For a uniform-thickness footing: 1.5 x 1.5 x 0.45 = 1.0125 m3 each. For 12: 12.15 m3.
If the footing is sloped or stepped, add a base slab and a frustum:
V = (L x B x H1) + (h / 3) x (A1 + A2 + sqrt(A1 x A2))
Here A1 is the area at the bottom of the sloped part, A2 the area at its top, and h its height. For a 1.6 m x 1.6 m base tapering to 0.8 m x 0.8 m over 0.3 m: 0.3 / 3 x (2.56 + 0.64 + 1.28) = 0.448 m3.
Step 4: Column stub to ground level
Per footing: 0.30 x 0.30 x 0.95 = 0.0855 m3. For 12: 1.026 m3. Above ground level, column concrete is measured with the superstructure.
Step 5: Formwork (shuttering)
Only the sides need formwork; the base sits on the PCC. Per footing: perimeter 4 x 1.5 = 6.0 m x 0.45 m = 2.7 sqm. For 12: 32.4 sqm. Add column stub sides if your item measures them here.
Step 6: Reinforcement
Bars each way: (1.5 - 2 x 0.05) / 0.15 + 1 = 10.3, so 10 bars per direction (round down to whole bars). Bar length: 1.5 - 2 x 0.05 = 1.4 m. Unit weight of 12 mm bar: d squared / 162 = 144 / 162 = 0.889 kg per m.
Per footing: 20 bars x 1.4 m x 0.889 = 24.9 kg. For 12: about 299 kg.
This counts straight bottom bars only. Add bends, hooks, any top steel and column starter bars from the drawing. Use the bar bending schedule calculator and see how to calculate steel quantity and the bar bending schedule format.
Step 7: Backfilling
Backfill = excavation minus everything placed in the pit.
52.02 - 3.468 (PCC) - 12.15 (footing) - 1.026 (stub) = 35.376 m3
Measurement sheet
| Item | Nos | L (m) | B (m) | D (m) | Quantity | Unit |
|---|---|---|---|---|---|---|
| Excavation | 12 | 1.70 | 1.70 | 1.50 | 52.02 | m3 |
| PCC bed | 12 | 1.70 | 1.70 | 0.10 | 3.468 | m3 |
| RCC footing | 12 | 1.50 | 1.50 | 0.45 | 12.15 | m3 |
| Column stub | 12 | 0.30 | 0.30 | 0.95 | 1.026 | m3 |
| Formwork to footing sides | 12 | 6.00 (perimeter) | - | 0.45 | 32.4 | sqm |
| Reinforcement (bottom mat) | 12 | - | - | - | 298.7 | kg |
| Backfilling | - | - | - | - | 35.376 | m3 |
Step 8: Convert concrete volume to materials
Wet concrete volume is converted to dry volume with a factor of about 1.54, then split by the mix ratio.
Assumed mixes: M20 nominal (1 : 1.5 : 3) for the footing and stub, and 1 : 4 : 8 for the PCC.
| Part | Wet volume | Dry volume | Cement | Sand | Aggregate |
|---|---|---|---|---|---|
| RCC footing + stub (1 : 1.5 : 3) | 13.176 m3 | 20.29 m3 | about 106 bags | about 195 cft | about 391 cft |
| PCC (1 : 4 : 8) | 3.468 m3 | 5.34 m3 | about 12 bags | about 58 cft | about 116 cft |
Cement bags use 1,440 kg per m3 and 50 kg per bag. Sand and aggregate use 35.31 cft per m3. These are net quantities, before wastage.
How the quantities become BOQ items
In a DSR-based BOQ, each line becomes a separate item with its own unit: earthwork in excavation (cum), PCC (cum), RCC (cum), formwork (sqm), reinforcement (kg or quintal) and backfilling (cum). Concrete, formwork and steel are separate items. Do not assume the concrete rate covers steel or formwork. See DSR 2023 explained and units of measurement in an Indian BOQ.
Skip the hand calculation
The Detailed Estimate reads footing schedules from your structural drawings and calculates excavation, PCC, footing concrete and footing steel for you to check. It does not calculate footing formwork; take that from Step 5. For the full method, see how to make a BOQ from drawings.
Frequently asked questions
How do you calculate the concrete quantity of an isolated footing?
Multiply length x breadth x thickness for each footing, then multiply by the number of footings. Add a frustum term if the footing is sloped.
What is the excavation depth for a footing?
It is the depth from ground level to the underside of the PCC bed, as shown on the foundation drawing.
Is PCC measured to the footing size?
No. The PCC bed usually projects beyond the footing, commonly by 75 to 100 mm on each side. Use the size on the drawing.
Why is backfill less than excavation?
Because the PCC, footing and column stub occupy part of the excavated pit.
Do I add wastage to these quantities?
Measure net quantities in the BOQ. Add wastage when you convert to purchase quantities.