M20 Concrete for a 1000 sq ft Slab in India
A 1000 sq ft roof slab at 5 inches thick in M20 grade (1:1.5:3) needs about 90 fifty-kg cement bags, 170 CFT sand and 340 CFT aggregate. Select M20 in the Concrete Calculator grade dropdown and it computes all three instantly โ this guide shows the hand math so you can check any estimate.
Step-by-Step Takeoff
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1
Volume: 1000 sq ft x 0.416 ft = 416 CFT wet volume.
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2
Dry volume: 416 x 1.54 = 641 CFT of dry material.
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3
M20 split 1:1.5:3 over 5.5 parts: cement 117 CFT, sand 175 CFT, aggregate 350 CFT.
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4
Cement: 117 CFT x 1440 kg/m3 / 50 kg = about 90 bags; sand 175 CFT; aggregate 350 CFT.
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5
Add 5% wastage on cement, 7% on sand and aggregate for handling losses.
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6
Order water for curing too: ponding a 1000 sq ft slab needs roughly 2000 litres over 7 days.
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7
Price it with your local 50 kg bag rate in the calculator and export the quote.
Guide FAQ
M20 or M25 for a roof slab?
M20 is standard for residential roof slabs; use M25 for heavy loads or commercial spans.
Why 50 kg bags?
Indian cement sells in 50 kg bags; one bag is about 1.24 CFT.
How much sand for 1000 sq ft slab?
About 175 CFT (roughly 6 brass) for M20 at 5 inches.
What is one brass in CFT?
100 CFT โ sand and aggregate are commonly quoted per brass.
How many days to cure a roof slab?
Keep it wet 14 days minimum for roof slabs; props stay 14โ21 days.
Related Guides
How Many Bags of Concrete for a 10ร10 Slab?
Bag count, cubic yards, and cost for the classic 10x10 patio slab at 4 inches thick. Includes ready-mix breakpoint and curing plan.
How Much Steel per Sq Ft for a House in India?
TMT thumb rules per element โ footing, column, beam, slab and staircase rates for Indian homes.
Why Multiply Concrete Volume by 1.54?
The dry-volume factor explained with a worked M20 example, US equivalents, and limits.