Concrete Mix Calculator
How much cement, sand, gravel and water for any ratio or strength
Turn these numbers into a build plan.
- 3000 psi strength
- 1:2:4 ratio
- 7 bags cement
Cut list: Concrete Mix Calculator
- Concrete volume (with 10% waste)1.10 cu yd (29.7 cu ft, 0.84 m³)
- Mix ratio1:2:4 (about 3000 psi), w/c 0.50
- Portland cement7 bags of 94 lb (614 lb, or 7 bags of 40 kg)
- Sand0.48 cu yd, 0.65 tons
- Gravel (3/4 in)0.97 cu yd, 1.37 tons
- Water37 gallons (139 L)
- Hand mix or ready-mix?About 10 mixer batches. Ready-mix is usually cheaper above 1 cu yd.
- Total cost$199.88 ($181.71 per cu yd)
- [ ] Portland cement, 94 lb (7)$112.00
- [ ] Concrete sand (0.65 tons)$26.14
- [ ] 3/4 in gravel (1.37 tons)$61.75
- [ ] Same pour in 80 lb premix bags50 bags
- [ ] Portland cement, 94 lb
- [ ] Concrete sand
- [ ] 3/4 in gravel aggregate
- [ ] Clean water
- [ ] Plastic sheeting for curing
- [ ] Tarps for sand and gravel piles
- [ ] Air entraining admixture
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Mix 1.1 yd³ of 3000 psi concrete
Batch 1.1 cubic yards at a 1:2:4 ratio: 7 bags of portland cement, 0.48 yd³ sand, 0.97 yd³ gravel, and about 37 gallons of water (w/c 0.50). Planned as 10 mixer batches for a small pour.
- Materials
- $302
- Time
- 1 day
- Level
- Easy
- 1
Confirm the job and the volume
3000 psi at 1:2:4 suits patios, walks, and small slabs. Anything structural (footings for a house addition, retaining walls) needs a permit and the mix the plans call for.
- Match psi to the job
- Check permit needs for structural pours
- Confirm forms are built and braced
- 2
Stage materials
Have 7 cement bags on pallets under cover and sand and gravel piles near the mixer. Mark your measuring bucket so each part is the same size.
- Cement off the ground and dry
- Sand and gravel within shovel reach
- Measuring bucket marked
- 3
Mix a test batch
With the mixer running, add about half the water, then load the 1:2:4 ratio by bucket: 4 gravel, 2 sand, 1 cement. Add the rest of the water slowly until the mix holds a shape like thick oatmeal.
- Water and gravel first
- Then sand, then cement
- Mix 3 to 5 minutes
- Strength
- 3000 psi
- Ratio
- 1:2:4
- Cement
- 7 bags
- Est. cost
- $302
7 steps · 8 tools · 7 materials
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Concrete mix ratios by strength
| Ratio | Strength | Water-cement | Metric grade | Typical use | Cement per cu yd |
|---|---|---|---|---|---|
| 1:1.5:3 | 4000 psi | 0.45 | M25 | Driveways, garage floors, structural footings (add air entrainment in freeze-thaw areas) | 8 bags |
| 1:2:3 | 3500 psi | 0.48 | M20 to M25 | Patios, sidewalks, steps | 7 bags |
| 1:2:4 | 3000 psi | 0.50 | M15 to M20 | Slabs, footings, fence and deck posts | 6 bags |
| 1:2.5:5 | 2500 psi | 0.55 | M10 to M15 | Light-duty pads, shed bases | 5 bags |
| 1:3:6 | 2000 psi | 0.60 | M10 | Lean fill, mud slabs, under footings | 5 bags |
Ratios are by volume, measured with the same bucket. Strengths are typical for a well-cured hand mix; anything structural should follow the mix your plans or inspector call for.
How to calculate a concrete mix
Worked example: a 10 x 10 ft slab, 4 in thick, at 1:2:4.
- Find the wet volume. Multiply length x width x thickness in feet. A 10 x 10 ft slab 4 in thick is 33.3 cu ft; with 10% waste, 36.7 cu ft.
- Convert to dry volume. Multiply by 1.54, because dry cement, sand and gravel shrink when water fills the voids: 56.5 cu ft.
- Split by the ratio. A 1:2:4 mix has 7 parts. Cement is 1/7 of the dry volume (8.07 cu ft), sand 2/7 (16.1 cu ft) and gravel 4/7 (32.3 cu ft).
- Convert cement to bags. Portland cement weighs 94 lb per cubic foot, and one bag is one cubic foot: 9 bags.
- Work out the water. Water = cement weight x water-cement ratio / 8.34 lb per gallon: 758 x 0.50 / 8.34 = 45 gallons.
Result: 9 bags of cement, 0.60 cu yd (0.81 tons) of sand, 1.20 cu yd (1.69 tons) of gravel and 45 gallons of water. Need the volume for a shape first? Use the concrete volume calculator or the concrete slab calculator, then come back for the mix.
Water, air and curing
Water. Every extra gallon above the water-cement ratio costs strength. Mix to a stiff oatmeal consistency and resist adding more to make it pour easier.
Freeze-thaw areas. Outdoor slabs and driveways in cold climates should use air-entrained concrete (premix bags labeled for it, or an admixture), which survives freeze-thaw cycles much better.
Curing. Keep it damp or covered for 7 days. Concrete reaches about 70% of its strength in 7 days and its rated strength at 28 days. Below the slab, a compacted base matters as much as the mix: size it with the gravel calculator, and add steel with the rebar calculator. Setting posts? Follow the fence building guide, and keep the concrete cheat sheet handy on pour day.
Concrete mix FAQ
What is the mix ratio for 3000 PSI concrete?
How many bags of cement are in a yard of concrete?
How much sand and gravel per bag of cement?
How many 80 lb bags of concrete make a yard?
Can I use 1:2:3 for a driveway?
How much water per 80 lb bag of concrete?
Should I mix by hand or order ready-mix?
Why multiply by 1.54?
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