Concrete Mixer Ratio Calculator

Calculate precise amounts of cement, sand, gravel, and water for your project. Choose a standard mix ratio or enter your own.

Project Details

Material Estimate

Enter your volume and ratio, then click Calculate.

How to use this concrete mix calculator

  1. Enter the volume you need (yards, feet, or meters).
  2. Pick a preset ratio or choose Custom for specialty mixes.
  3. Review the estimated weights and bag count. Water is shown at ~0.5x cement weight.
  4. Round up bags to cover handling loss and site conditions.

Tip: If your aggregates are very wet, slightly reduce the added water to maintain the desired slump.

Popular concrete mix ratios & where they’re used

1:2:3 (Cement:Sand:Aggregate)

General purpose slabs, patios, walkways.

1:1.5:3

Columns, beams, and structural members needing higher strength.

1:3:5

Footings and mass concrete where strength is moderate and volume is large.

1:4:8

Lean concrete for bedding, sub-base layers, and blinding.

5 Fun Facts About Concrete

Ancient Tech

Romans used volcanic ash (pozzolana) to make concrete that set underwater and lasted millennia.

Roman recipe

Still Curing

Concrete never truly stops curing; it keeps gaining strength for years. The Hoover Dam is still slowly curing.

Long game

Weak in Tension

Concrete is strong in compression but weak in tension—steel reinforcement handles the pull forces.

Rebar needed

Sugar Retarder

A little sugar can delay setting; enough sugar can halt it entirely. Don’t spill your coffee in the drum.

Chemistry

Most Used

Concrete is the most widely used man-made material on Earth—second only to water as a global resource.

Everywhere

Concrete mix basics: a quick field guide

Concrete is just four ingredients—cement, water, sand, and coarse aggregate—but small tweaks change strength, finish, and workability. Use this guide to dial in the right mix, reduce cracking, and waste less material on-site.

Pick the right water-cement ratio

Most everyday mixes land between 0.45 and 0.55 water-to-cement ratio by weight. Lower water gives higher strength but is harder to place; higher water is easier to pour but reduces strength and increases shrinkage. The calculator assumes ~0.50 for a workable slump—adjust slightly based on your aggregate moisture and desired consistency.

Know your aggregates

  • Sand (fine aggregate): Damp, well-graded sand helps packing density. Very dry sand will absorb water after mixing; saturated sand will add water you didn’t plan for.
  • Gravel/crushed stone (coarse): Rounded river gravel improves workability; angular crushed stone interlocks for strength but needs more paste to coat surfaces.
  • Maximum size: A larger top size lowers water demand but must still flow around rebar and into corners. If you see honeycombing, reduce size or add vibration.

Adjusting slump and finish

For flatwork like patios, a medium slump (3–5 in / 75–125 mm) is common. For walls or congested rebar, slightly higher slump or a plasticizer can improve placement without over-watering. Avoid “souping up” on-site with extra water—it weakens the surface and increases dusting.

Curing matters as much as the mix

Keep fresh concrete damp and shaded for at least 7 days for typical Portland cement mixes; 14 days is better for structural strength. Rapid drying causes shrinkage cracks and weaker surfaces. Use curing blankets, plastic sheeting, or a curing compound to trap moisture—especially in hot, windy, or very cold weather.

Safety and handling tips

  • Wear gloves and eye protection—cement is caustic and can burn skin.
  • Use dust masks when handling dry cement to avoid inhalation.
  • Clean tools promptly; cement paste gets harder to remove every minute it sits.

When to choose a different ratio

Use 1:1.5:3 for higher-strength columns and beams, 1:2:3 for general slabs and paths, 1:3:5 for footings and mass pours, and lean 1:4:8 mixes for bedding or blinding layers. If you need higher early strength, consider Type III cement or a commercial accelerator rather than adding extra cement indiscriminately.

On-site conditions always win: if the mix feels too stiff, add water in very small increments and remix thoroughly; if it’s too loose, add a bit of cement and sand in the same ratio to restore balance.

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