Cement Calculator
List the work, such as slabs, beams, columns, footings, plaster and floor beds, and get the cement bags, sand, aggregate and water for each and in total, with the cost. Or get a quick figure from your built-up area.
1Breakdown
Where the cement goes
Cement, sand and aggregate for each item in your list.
| Work | Mix and volume | Cement bags | Sand cum | Aggregate cum |
|---|---|---|---|---|
| RCC slab | M20 1:1.5:3, 8.71 cum | 70.3 | 3.66 | 7.32 |
| RCC beams | M20 1:1.5:3, 3.47 cum | 28.0 | 1.46 | 2.91 |
| RCC columns | M20 1:1.5:3, 2.52 cum | 20.4 | 1.06 | 2.12 |
| Footings | M20 1:1.5:3, 8.03 cum | 64.8 | 3.37 | 6.74 |
| PCC bed | M7.5 1:4:8, 2.26 cum | 7.7 | 1.07 | 2.14 |
| Brick mortar | 1:6 mortar, 8.01 cum | 43.9 | 9.13 | — |
| Plaster | 1:6 mortar, 4.46 cum | 24.4 | 5.08 | — |
| Plaster | 1:4 mortar, 2.25 cum | 17.2 | 2.39 | — |
| Floor bed | 1:4 mortar, 2.79 cum | 21.4 | 2.97 | — |
| Total with wastage | 304 | 31.70 | 22.29 |
2Grades
M20, M25 and other grades: what they mean
The number after M is the strength the concrete should reach after 28 days of curing, in N/mm² (newton per square millimetre). M20 means 20 N/mm². A higher grade needs more cement per cubic metre, so it costs more but carries more load and lasts longer in harsh conditions.
M7.5
1 : 4 : 8 · 7.5 N/mm²Use for: lean PCC bed below footings and plinth beams, levelling courses.
Not for: anything with steel in it.
M10
1 : 3 : 6 · 10 N/mm²Use for: PCC under floors, base for tiles and pavers, pathways.
Not for: slabs, beams or columns.
M15
1 : 2 : 4 · 15 N/mm²Use for: plain concrete floors, ramps, steps and PCC in wetter conditions.
Not for: structural RCC members.
M20
1 : 1.5 : 3 · 20 N/mm²Use for: RCC slabs, beams, columns and footings of houses in mild conditions. The usual minimum grade for RCC.
Watch: the highest grade normally made by nominal mix on site.
M25
1 : 1 : 2 · 25 N/mm²Use for: RCC exposed to rain, soil or moisture, columns of taller buildings, water tanks.
Watch: better as a lab design mix or ready-mix; the 1:1:2 here is only a guide.
M30 and above
Design mix onlyUse for: coastal and severe exposure, high-rise frames, bridges, heavy industrial floors.
Watch: not calculated here; mix proportions come from a lab design.
3Choose
How to pick the right grade and cement
Answer three questions: does the concrete have steel in it, how wet or harsh is its surrounding, and what do the structural drawings say. The drawings always win.
OPC 53
Ordinary Portland CementGains strength fastest; used for RCC where early formwork removal matters and in precast work. Needs good curing.
OPC 43
Ordinary Portland CementGeneral purpose for RCC, plaster and masonry with steadier strength gain.
PPC
Portland Pozzolana CementWidely used for houses: plaster, masonry, foundations and RCC; slower early strength but good long-term durability.
PSC
Portland Slag CementUsed for marine works, large foundations and mass concrete where resistance to chemical attack matters.
Follow your structural drawings. Indian practice under IS 456 allows nominal mixes only up to M20; for M25 and above, ask for a design mix or ready-mix concrete, and never reduce the grade your engineer specified to save cement.
4Reference
Mix ratios at a glance
Materials for one cubic metre of finished concrete or mortar, and for common plaster and floor jobs, before wastage.
| Mix | Use | Cement bags | Sand cum | Aggregate cum |
|---|---|---|---|---|
| M7.5 (1:4:8) | PCC under footings, per cum | 3.4 | 0.47 | 0.95 |
| M10 (1:3:6) | PCC, floor base, per cum | 4.4 | 0.46 | 0.92 |
| M15 (1:2:4) | Light RCC, pathways, per cum | 6.3 | 0.44 | 0.88 |
| M20 (1:1.5:3) | Slabs, beams, columns, per cum | 8.1 | 0.42 | 0.84 |
| M25 (1:1:2) | Heavier RCC, per cum | 11.1 | 0.39 | 0.77 |
| Mortar 1:3 | Per cum of mortar | 9.6 | 1.00 | — |
| Mortar 1:4 | Per cum of mortar | 7.7 | 1.06 | — |
| Mortar 1:5 | Per cum of mortar | 6.4 | 1.11 | — |
| Mortar 1:6 | Per cum of mortar | 5.5 | 1.14 | — |
| Plaster 12 mm, 1:6 | Per 100 sq.ft. | 0.61 | 0.127 | — |
| Plaster 20 mm, 1:4 | Per 100 sq.ft. | 1.42 | 0.198 | — |
| Floor bed 40 mm, 1:4 | Per 100 sq.ft. | 2.85 | 0.395 | — |
5Method
How the quantities are worked out
The dry volume method used on Indian sites, applied to each row and added up.
- Nominal mixes. M7.5 to M25 use nominal proportions by volume. For M25 and above, a lab design mix usually uses less cement for the same strength.
- Brick mortar. About a quarter of a traditional brick wall is mortar; the brick row uses that share. The brick quantity calculator works it out exactly.
- Plaster. Area × thickness, with the 1.33 factor covering joints and uneven walls.
- Steel is not deducted. Reinforcement takes 1 to 2% of concrete volume, which is within wastage.
6Scope
What this calculator does and does not do
Knowing the limits helps you add the right margin before you place an order.
✓It does
- Work out cement, sand, aggregate and water for each item
- Cover slabs, beams, columns, footings, PCC, brick mortar, plaster and floor beds
- Use nominal mixes M7.5 to M25 and mortar mixes 1:3 to 1:6
- Add wastage and price the materials
- Give a quick figure from built-up area
- Give an order list, CSV, shareable link and print
✕It does not
- Design a concrete mix or account for admixtures
- Replace the grade on your structural drawings
- Include steel, shuttering, labour or curing
- Price ready-mix concrete, pumping or transport
- Know your local prices; change the rates to match your supplier
7FAQ
Questions
How many cement bags are needed for 1 cubic metre of concrete?
Using nominal mixes and a dry volume factor of 1.54, about 3.4 bags for M7.5 (1:4:8), 4.4 bags for M10 (1:3:6), 6.3 bags for M15 (1:2:4), 8.1 bags for M20 (1:1.5:3) and 11.1 bags for M25 (1:1:2). The table on this page lists sand and aggregate too.
How is cement quantity calculated?
Find the wet volume of the work: length × width × thickness. Convert it to dry volume by multiplying by 1.54 for concrete or 1.33 for mortar, because dry materials shrink when water is added and voids fill up. Cement volume = dry volume × cement parts ÷ total parts, and one 50 kg bag is about 0.0347 cum (cement weighs about 1,440 kg per cum).
How much cement is needed for plastering?
For 12 mm plaster in 1:6, about 0.6 bags per 100 sq.ft. (0.07 bags per sq.m). For 20 mm external plaster in 1:4, about 1.4 bags per 100 sq.ft. (0.15 bags per sq.m). Add a plaster row in the calculator with your wall area and thickness.
How many bags of cement are needed for a 1,000 sq.ft. house?
A common thumb rule for a complete RCC house is about 0.4 bags per sq.ft. of built-up area, so about 400 bags for 1,000 sq.ft. The From built-up area tab uses 0.35, 0.40 or 0.45 bags per sq.ft. by quality. For a firm order, list the actual work items in the Work by work tab.
What is the difference between M15, M20 and M25?
The number is the strength in N/mm² after 28 days. Nominal mixes give approximate proportions: M15 is 1:2:4, M20 is 1:1.5:3 and M25 is 1:1:2. Slabs, beams and columns in houses are usually M20 or higher; PCC under footings is often M7.5 or M10. For M25 and above, a design mix from a lab is recommended.
How much water is needed?
The calculator uses a water-cement ratio of 0.5 for concrete, which is about 25 litres per 50 kg bag. Your engineer may specify a lower ratio for stronger concrete. Mortar water is not shown because masons add it by workability.
What is a brass?
A brass is 100 cubic feet, about 2.83 cubic metres. Sand and aggregate are shown in cum, cft and brass so you can order in the unit your supplier uses.
Is my data stored?
No. The calculator runs in your browser and loads no third-party scripts. Inputs leave the page only if you copy the link, share on WhatsApp or download the list.
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