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Cement Calculator

How many bags of cement a job needs — any concrete mix or mortar, with the working shown.

Construction● Free Formula shown Rates dated
Quick Answer

One cubic metre of M20 concrete (1:1.5:3) takes about 8.1 bags of cement — 8.3 once the 3% wastage allowance is added, so 9 whole bags — while 100 sq ft of 12 mm internal plaster in 1:6 takes 0.61 bags, or 0.63 with the same allowance. At ₹320–415 a bag for OPC 43 (as of Jul 2026) that cubic metre costs ₹2,880–3,735 in cement alone. Bags = volume × dry factor ÷ total parts in the mix ÷ 0.0347 m³ per bag. Enter your job below for the count, the weight and the cost.

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The Formula

Cement bags = volume of the work × dry factor ÷ total parts in the mix ÷ 0.0347 m³ per bag, + 3% wastage

The dry factor is 1.54 for nominal-mix concrete and 1.33 for cement-sand mortar: loose dry ingredients carry air voids that the finished mix does not, so you buy more material than the volume you end up with. Cement is always the 1 in the ratio, so 1:1.5:3 is 5.5 parts and cement is 1/5.5 of the dry volume. One 50 kg bag occupies 0.0347 m³ (about 1.23 cft) at the conventional 1,440 kg/m³ loose bulk density.

Assumptions & Wastage

  • Volume of the work = length × width × thickness. Length and width are in feet; thickness is in inches, millimetres or feet as you choose. For plaster, width is the height of the face and thickness is the plaster thickness in mm
  • Concrete converts wet volume to dry ingredients at 1.54 and cement-sand mortar at 1.33 — the same factors the concrete, brick and plaster calculators on this site use, so the four never disagree about the same pour or the same wall
  • Nominal mix ratios are volumetric site convention: M7.5 = 1:4:8, M10 = 1:3:6, M15 = 1:2:4, M20 = 1:1.5:3, M25 = 1:1:2. IS 456:2000 clause 9.3 permits nominal mixes only up to M20; the M25 option is site practice, not code, and anything M25 or above should be a design mix to IS 10262
  • One cement bag = 50 kg = 0.0347 m³ at 1,440 kg/m³. That density is a trade convention rather than a measured constant — loose cement runs roughly 1,200–1,440 kg/m³ depending on how aerated it is — so the volume figure is nominal. IS 2250 sidesteps the problem entirely by requiring cement to be proportioned in full bags only
  • 3% cement wastage is added on top of the computed base quantity, using the published allowance below. Nothing is pre-included, so do not add wastage again
  • Cement is sold in whole bags, so the 'to buy' figure and the cost line round up. The bag count itself stays fractional so several pours can be totalled before rounding
  • For mortar, enter the volume of the mortar itself. In brickwork the mortar is only about a fifth of the wall volume — use the brick calculator for a wall rather than entering wall dimensions here
  • Costed at the dated national retail band for the cement type you pick. GST on cement was cut from 28% to 18% with effect from 22 September 2025, which is already reflected in the Jul 2026 bands below; note that no dealer price list we could find states its tax basis, so GST-inclusive is inferred rather than quoted. All four types — OPC 43, OPC 53, PPC and PSC — now carry a dated rate, and OPC 43 and OPC 53 deliberately share one band because retail does not price the grade apart
  • Official Indian sources do not agree on cement consumption to better than about 10%. For 1:1.5:3 concrete, CPWD's rate-analysis coefficient of 4.00 quintal per m³ works out to 8.00 bags against the 8.07 this calculator computes, while IS 10067:1982 (Material Constants in Building Works) publishes 7.33. The volumetric route used here sits at the generous end of that spread — it will not under-order
MaterialWastage allowance
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Worked Examples

RCC roof slab, 12 × 10 ft at 5 inches, M20, OPC 43

  1. Volume: 12 × 10 ft × 5 in = 50 cft = 1.416 m³ of finished concrete
  2. Dry volume: 1.416 × 1.54 = 2.18 m³
  3. M20 is 1:1.5:3, so 5.5 parts: 2.18 ÷ 5.5 = 0.3964 m³ of cement
  4. Bags: 0.3964 ÷ 0.0347 = 11.42 bags; +3% wastage = 11.77 bags (588 kg) → buy 12 whole bags
  5. Cement cost: ₹3,840 to ₹4,980 (as of Jul 2026). Sand, aggregate and water are extra — the concrete calculator prices the whole pour

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Internal plaster, 20 × 10 ft face at 12 mm, 1:6 mortar, PPC

  1. Volume: 20 × 10 ft × 12 mm = 7.87 cft = 0.223 m³ of finished mortar
  2. Dry volume: 0.223 × 1.33 = 0.297 m³
  3. 1:6 mortar is 7 parts: 0.297 ÷ 7 = 0.0424 m³ of cement
  4. Bags: 0.0424 ÷ 0.0347 = 1.22 bags; +3% wastage = 1.26 bags (63 kg) → buy 2 whole bags
  5. Cement cost: ₹560 to ₹800 (as of Jul 2026), because you cannot buy a fraction of a bag — this wall needs 1.26 bags and you must buy two, leaving nearly three-quarters of a bag for the next wall. Total several walls before rounding up

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PCC levelling bed, 20 × 15 ft at 4 inches, M10, OPC 43

  1. Volume: 20 × 15 ft × 4 in = 100 cft = 2.832 m³ of finished concrete
  2. Dry volume: 2.832 × 1.54 = 4.361 m³
  3. M10 is 1:3:6, so 10 parts: 4.361 ÷ 10 = 0.4361 m³ of cement
  4. Bags: 0.4361 ÷ 0.0347 = 12.57 bags; +3% wastage = 12.94 bags (647 kg) → buy 13 whole bags
  5. Cement cost: ₹4,160 to ₹5,395 (as of Jul 2026). At 222 kg of cement per m³ this is a plain-concrete grade — fine under a floor or a footing, never for reinforced work

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Rates & Model Data Used

Every number below is a range with a date — material prices in India move quickly, so always check the "as of" month before relying on a figure.

ItemRate / valueAs ofNote
Cement (OPC 43 grade)₹320–415 / bag (50 kg)Jul 2026Per 50 kg bag as listed by retail sources; no dealer page in the set states a tax basis, so GST-inclusive at 18% is inferred, not quoted — a strong inference, but an inference, and the reason this is medium rather than high. Re-baselined 2026-07-24: the band was ₹340–410 at high confidence, resting on two content farms plus official anchors that turn out to be estimating conventions rather than market evidence. Grade does not move the retail price. On the only dated price list found that quotes both grades (Bangalore, 6 Jul 2026, seven brands), five of seven price OPC 43 and OPC 53 identically to the rupee, the mean difference is −₹1.79/bag and the median is exactly zero — so OPC 53 carries this same band. No Indian government schedule prices the grades apart either: CPWD DAR 2023 carries a single grey-cement rate of ₹5,156/t and lets estimators substitute ordinary, pozzolana or slag against it, and WPI has no OPC 53 series. That is an accounting convention rather than proof about the market, but not one official source in the country supports paying more for 53. What does move the price: brand ₹75/bag (Maha ₹335 against UltraTech ₹410, same list, same day — 22%) and city ₹35/bag (ACC OPC 53 ₹395 Bangalore against ₹360 Hyderabad, 570 km apart). Against those, grade at zero is a rounding error. Bulk orders of 100+ bags take another ₹10–20/bag off. GST moved 28% → 18% on 22-09-2025 (CBIC Notification 9/2025, heading 2523, which names slag cement expressly); any bag price published before Oct 2025 is on the old regime — multiply by 1.18/1.28 = 0.9219, a 7.8% fall, before comparing. Cost check: ₹320 incl. = ₹5,424/t ex-GST against CPWD's ₹5,156/t ex-GST ex-carriage bulk Delhi (Apr 2023) = +5.2%, which leaves about 5% for carriage plus the whole dealer chain — thin, and only plausible near a plant, which is what a value brand in a southern clinker market is. Cement WPI has moved between −3% and +2% since Apr 2023, so no inflation adjustment to that anchor is warranted. Declared weaknesses: the ₹400–415 ceiling is two lines on one Bangalore page (verbatim-confirmed by three independent readers, uncorroborated elsewhere — the one corroborator refused connection), first-hand retail evidence is two southern cities plus one Delhi single-brand list, and July is near the seasonal trough since cement softens through the monsoon and firms in the Jan–Mar infrastructure season. Treat as a national indicative band and check your own market.
Cement (OPC 53 grade)₹320–415 / bag (50 kg)Jul 2026Deliberately the same band as OPC 43, because nothing we can read shows a retail premium to justify a different one. On the only dated list found quoting both grades (Bangalore, 6 Jul 2026, seven brands, read independently by three people), five of seven price the two grades identically to the rupee; the mean difference is −₹1.79/bag and the median is zero. It is one dealer, one city, one day, seven pairs — not a national measurement, and it is not dressed up as one. What supports it is the absence on the official side: no Indian government schedule prices the grades apart, and WPI has no OPC 53 series to sample. Publishing a higher band for OPC 53 would assert a premium the evidence does not support, so an identical band is also the conservative choice. Buy OPC 53 for what IS 269:2015 actually requires of it — 27 MPa at 3 days against 43 grade's 23 — when formwork has to come off fast, not because it costs more. Same tax basis, same GST history and the same declared weaknesses as the OPC 43 entry.
Cement (PPC)₹280–400 / bag (50 kg)Jul 2026Re-baselined 2026-07-24 from ₹330–400. The discount over ordinary Portland is roughly double what this entry used to publish: PPC runs ₹30–40/bag below the SAME brand's OPC, not ₹10–30. Eight same-brand pairs in Bangalore average −₹33.75 (median −₹35) and seven in Hyderabad average −₹35.00 (median −₹30); both hold up after dropping the one wild pair and any duplicated line, and CPWD's Clause 10CA Dec 2025 base prices give −₹33.90/bag ex-GST (−₹40 grossed at 18%) as corroboration. Note the wide top: premium blended products such as ACC Suraksha Power and UltraTech Weather Plus sell at ₹375–400 and are priced as premium goods, not as the cheap alternative to their own maker's OPC — so the ₹30–40 saving is a same-brand, same-shop comparison, and the band ceiling sitting only ₹15 below OPC's is not a contradiction of it. The ₹280 floor is a value-brand observation, not an ordinary counter price: stripped of GST it sits about 6% above CPWD's 2023 bulk ex-carriage Delhi base once the measured PPC differential is applied, which leaves almost nothing for freight and margin and is only possible near a plant. Preferred for masonry and plaster, and code-legal for RCC — IS 456:2000 cl. 5.1 lists PPC among the cements permitted for plain and reinforced concrete — but cl. 13.5.1 asks for at least 10 days of wet curing where blended cements are used, against 7 for ordinary Portland. Same inferred GST-inclusive basis, same 28% → 18% history and the same geographic thinness as the OPC entry; medium for those reasons.
Cement (PSC — Portland slag)₹290–400 / bag (50 kg)Jul 2026The widest of the four cement bands, and the width IS the finding: the sign of the slag differential is unresolved. In Bangalore, same brand and same day, Maha's PSC costs ₹30/bag less than Maha's OPC 43 — −8.96%. The only official Indian schedule that prices slag cement separately says the opposite: Maharashtra PWD's 2022-23 SoR puts PSC at ₹6,385/t against PPC's ₹6,000/t, so slag is 6.4% DEARER. CPWD sidesteps it entirely with one rate for all three. The differential therefore runs from −9% to +6.4% with no national centre, which is why this band overlaps both its siblings. Do not choose PSC to save money — choose it for sulphate and chloride resistance (IS 455:2015), and check the price on the day, where you are buying. Evidence is fourteen listings across eleven cities and three independent B2B platforms: the ₹290 floor is four listings in three cities on two platforms (and includes a 17% promotional discount off a ₹350 list — the normal PSC counter floor observed is ₹300–310), and the ₹400 ceiling is three listings at ₹385–400 across three cities and two platforms. Declared outlier above the band: Bangur, Gurugram, ₹425, single quote. Heading 2523 of CBIC Notification 9/2025 names slag cement expressly, so PSC is at 18% GST by name rather than by inference; the same inferred GST-inclusive retail basis as the other three applies to the listings themselves.

How to Use This Calculator

  1. Pick the mix. M20 for house slabs, beams and columns; M10 or M7.5 for levelling beds and mass fill; 1:6 mortar for internal plaster and brick masonry; 1:4 for external faces; 1:3 for repairs and waterproof pointing.
  2. Measure the element. Length and width in feet, thickness in inches for concrete or millimetres for plaster. Run it once per element and add the fractional bag figures before rounding up.
  3. Choose the cement type. OPC 43 for structural concrete, PPC for masonry and plaster, OPC 53 where formwork must come off fast, PSC for sulphate or chloride exposure. It changes the price, not the quantity — and it changes how long you must cure.
  4. Read the working. Every step is shown under the result and the rates used are dated in the table below. Take the whole-bag figure to the supplier and the working to your contractor.

Frequently Asked Questions

How many bags of cement are needed for 1 m³ of concrete?
On the volumetric mixes used across Indian sites, and before wastage: about 3.4 bags for M7.5 (1:4:8), 4.4 for M10 (1:3:6), 6.3 for M15 (1:2:4) and 8.1 for M20 (1:1.5:3) — roughly 170, 220, 315 and 400 kg of cement per m³. IS 456:2000 Table 9 lists five nominal-mix grades — M5, M7.5, M10, M15 and M20 — of which these four are the ones actually used, and it specifies them by mass of dry aggregate per 50 kg bag rather than by the volumetric ratios above. The familiar 1:1:2 'M25' is not in that table at all: it is trade convention, works out to about 11.1 bags (554 kg) and should really be a design mix. Official Indian sources bracket these rather than confirm them: CPWD's rate-analysis coefficients give 3.40, 4.40, 6.40 and 8.00 bags, while IS 10067:1982 publishes 3.20, 4.05, 5.84 and 7.33. Expect about 10% spread between honest methods.
How many cement bags does a 1,000 sq ft slab need?
At 5 inches thick in M20 a 1,000 sq ft slab is 11.8 m³ of concrete and needs about 95 bags before wastage, 98 with the 3% allowance, so 99 whole bags. At 4 inches it drops to about 79 bags and at 6 inches it rises to about 118. Per 100 sq ft of slab that is 7.8, 9.8 and 11.8 bags. All of that is the slab alone — a whole 1,000 sq ft house, counting footings, columns, slab, brickwork, plaster and flooring, runs 350 to 500 bags on this site's thumb rule of 0.35–0.50 bags per sq ft of built-up area. Single-storey builds sit near the bottom of that band and G+1 and above near the top, so estimate element by element for anything you are ordering against.
How do I convert cement bags to kg, cubic feet and cubic metres?
One bag is 50 kg declared and 0.0347 m³ by convention, which is 1.23 cft or about 34.7 litres — so a cubic metre of loose cement is roughly 28.8 bags. The volume follows from taking loose cement at 1,440 kg/m³, a trade convention rather than a measured constant: real loose density varies with how aerated the cement is, which is why IS 2250 requires cement to be proportioned in full bags rather than by volume. Two practical footnotes. The traditional 12 × 12 × 15 inch site gauge box holds 1.25 cft, about 2% more than a bag. And 50 kg is a declared quantity, not a guarantee per bag: the Legal Metrology (Packaged Commodities) Rules allow a 1% (500 g) maximum permissible error on an individual bag, while requiring the lot average to be at least 50 kg.
OPC 43, OPC 53, PPC or PSC — which should I buy?
Under IS 269:2015, which merged all three ordinary Portland grades into one standard, OPC 43 must reach 43 MPa at 28 days and OPC 53 must reach 53 MPa; PPC under IS 1489 (Part 1):2015 is a single class with the same 33 MPa floor as OPC 33; PSC is Portland slag cement to IS 455:2015. For a house, OPC 43 is the normal structural choice and PPC the normal choice for masonry and plaster — PPC is ground finer (minimum 300 m²/kg against 225 for OPC), so it holds water better and works more smoothly under a trowel. OPC 53 is worth choosing where formwork has to be struck fast, since it must reach 27 MPa at 3 days against PPC's 16 MPa; it is not the better cement for plaster, where its quicker set makes it harder to finish. PSC is the choice for sulphate or chloride exposure — coastal work, aggressive groundwater. What OPC 53 is <em>not</em> is dearer: on the only dated Indian price list we could find that quotes both grades, five of seven brands price OPC 43 and OPC 53 identically to the rupee, and no Indian government schedule prices the grades apart at all, so this site publishes one band for both. Pick the grade on what the concrete has to do, not on price.
Is PPC acceptable for an RCC slab, or do I need OPC?
PPC is code-legal for reinforced concrete. IS 456:2000 clause 5.1 lists ten cements permitted for plain and reinforced concrete, PPC to IS 1489 (Part 1) among them, and there is no clause anywhere requiring OPC 53 for columns — that is trade custom. The real trade-off is time, not strength: PPC gains strength more slowly, so IS 456 clause 13.5.1 requires at least 10 days of wet curing where blended cements are used against 7 days for ordinary Portland cement, and recommends extending that to 14. If nobody on site will keep a slab wet for two weeks, the ₹30–40 a bag you save on PPC is a false economy.
How long can cement be stored before it goes bad?
Indian bags are marked with a best-before date three months from packing and the wording 'Cement to be tested before use if more than 3 months old'. That is a retest trigger, not an expiry: IS 1489 (Part 1):2015 clause 14.2 says bagged cement held longer than three months shall be retested and rejected only if it then fails. Cement degrades on humidity rather than on the calendar — it absorbs moisture, sets partially in the bag and loses strength. IS 456 hands storage to IS 4082:1996, which asks for a dry, leakproof shed, bags stacked 150–200 mm off the floor and 600 mm clear of walls, no more than ten bags high, each stack date-labelled and used oldest first. A bag whose lumps will not crush between your fingers has already reacted — send it back rather than putting it in a slab.
Why does my mason use more cement than this calculator says?
Four reasons, all real. Cement is sold in whole bags, so a job needing 11.8 buys 12. Damp sand bulks 20–30% in loose volume, so a gauge box of site sand delivers less dry sand than intended and the mix comes out cement-rich — IS 456 clause 10.2.4 requires that bulking be corrected for, and almost nobody does the five-minute jar test in IS 2386 Part 3. Site mixes are routinely made richer than specified because nobody wants to be blamed for a weak slab. And spillage, part-used bags and an uneven substrate that eats extra plaster all cost bags that no formula predicts.
Does this include sand, aggregate, water and labour?
No — this is the cement question only, deliberately. For the sand, aggregate and water in a pour use the concrete calculator; for the sand in plaster use the plaster calculator; for bricks and the mortar between them use the brick calculator, because mortar is only about a fifth of a wall's volume and entering wall dimensions here would badly over-order. Labour, shuttering, reinforcement, admixtures, waterproofing and curing are all separate line items in a real estimate.
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Sources & Limitations

What this calculator does not model

  • Cement only — sand, aggregate, water, admixtures, reinforcement and labour are not included
  • One rectangular element per run; total several runs for a floor or a whole house
  • Volumetric nominal mixes over-order cement at the richer grades. IS 456 clause 9.1.1 concedes that a nominal mix is 'likely to involve a higher cement content' than a design mix, and at 1:1:2 the implied 554 kg/m³ exceeds the 450 kg/m³ that clause 8.2.4.2 advises against. Treat the answer as a procurement figure with slack in it, not a mix design
  • Assumes dry, unbulked sand. Damp sand bulks 20–30% and shifts the real proportions on any volume-batched site, which this calculator does not model
  • Does not model brickwork wall volume, ready-mix concrete ordered by the cubic metre, or bagged dry-mix products
  • Retail cement prices vary by state, brand and order size, and bulk orders of 100 bags or more typically save ₹10–20 a bag — the cost band uses the dated national range below