Concrete bag calculator
Volume and bag size: you get bags of premixed concrete, total weight and mixing water.
Purchase quantity
44 bag
Net measurement: 0.5 m³ · Waste 5 %
- Bags of dry concrete mix44 bag
- Total weight1100 kg
- Mixing water (≈ 0.12 l/kg)132 l
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How it's calculated (visible formula)
bags = ceil(volume × (1 + waste) ÷ yield per bag); 80 lb ≈ 0.6 cu ft, 60 lb ≈ 0.45 cu ft
- Net geometric measurement, no waste.
- Adjustable waste % for cuts and breakage.
- Purchase rounded up to sellable units (boxes, bags, buckets, boards).
How to calculate it, step by step
- Work out the concrete volume (use the concrete calculator if needed).
- Pick the bag size.
- Add 5% waste.
- Divide by yield per bag.
- Work out total mixing water.
Worked example: 17.7 cu ft (0.5 m³) with 55 lb (25 kg) bags
- 0.5 × 1.05 = 0.525 m³
- ÷ 0.012 m³ per bag ≈ 43.8
→ 44 bags (about 2,400 lb) — or about 31 bags of 80 lb.
Common mistakes
- Buying bags for more than a yard — ready-mix is cheaper.
- Too much water, which weakens the mix.
- Ignoring the weight for hauling.
Pro tips
- Use a mixer above 10–15 bags.
- Add water gradually — extra water weakens concrete.
- Rod or vibrate to remove voids.
- Keep it moist for the first days to cure.
From calculation to quote
Add labour, overhead and your margin, and generate the professional PDF.
FAQs
- How much does an 80 lb bag of concrete make?
- About 0.6 cu ft.
- How many 80 lb bags in a cubic yard?
- About 45.
- When should I order ready-mix?
- From about 1–1.5 yd³.
- How many 80 lb bags per cubic yard?
- About 45.
- What strength is bagged concrete?
- Typically 4,000 psi at 28 days for general-purpose mix.
- How much water per 80 lb bag?
- About 3 quarts; follow the bag.
Sources and standards
Maintained by Srikanta M · Formula v1.0.0 · Verified 2026-09-10 · Updated 2026-09-10 · Limits: quantity estimation, not structural design or site supervision.