How to Calculate Cement for a Footing (Foundation)

Footings are the first structural concrete many house builds order. They are usually simpler than slabs — a rectangle in the ground — but the grade and depth come from the drawing, not guesswork.

What to measure

For each strip footing or pad footing:

1. Length — along the wall line or column grid
2. Width — footing breadth (often 600 mm–900 mm for residential)
3. Depth — thickness from bottom of excavation to top of footing (often 300–500 mm)

Model irregular layouts as several rectangles and add volumes.

Step 1 — Wet volume

Wet volume = length × width × depth

Example: 6 m long strip, 0.6 m wide, 0.45 m deep

6 × 0.6 × 0.45 = 1.62 m³ (~57 cft)

Step 2 — Dry volume × 1.54

Dry volume = 1.62 × 1.54 = 2.49 m³

Same 1.54 factor as slabs — dry materials bulk larger than finished concrete.

Step 3 — Split by grade

Residential RCC footings often specify M20 or M25. For M20 (1:1.5:3, total 5.5 parts):

• Cement: 2.49 × (1/5.5) ≈ 0.45 m³ → ~13 bags (50 kg)
• Sand and aggregate: remainder in cft from the same split

Confirm grade on your structural drawing — footings are not the place to downgrade without engineer sign-off.

Step 4 — Material cost

Cost ≈ (bags × ₹/bag) + ((sand + aggregate) cft × ₹/cft)

For 13 bags @ ₹400 and ~120 cft combined sand/agg @ ₹55 → roughly ₹5,200 + ₹6,600 ≈ ₹11,800 materials only for this footing run.

Steel, shuttering, excavation, and labour are extra.

Multiple footings

Repeat for each run, or add volumes before splitting:

• Pad A: 1.2 m³
• Strip B: 1.62 m³
• Total wet = 2.82 m³ → then × 1.54 and grade ratio once

FAQ

Footing vs plinth beam?

This calculator models a solid rectangular pour. Plinth beams are also often rectangular — enter beam length × width × depth. For complex stepped footings, break into boxes.

M15 for footing?

Some drawings use lean concrete below the RCC footing (PCC bed). That is a separate pour — often M10/M15. See M15 and PCC.

Same as slab calculator?

Same math, different defaults. Use the Footing Calculator for foundation-oriented inputs and grades M10–M30.

---

Skip manual steps — Footing Calculator. Also see cement sand aggregate guide and materials to build a house.