Concrete Mix Ratio Calculator helps you size cement, sand, aggregate, and water from either part ratios (by volume) or proportion by mass (by weight), with input and results in metric and imperial units.
About units. The calculator works with both metric (m³, kg) and imperial (yd³, lb). Volumes can be entered in cubic meters or cubic yards; masses are returned in kilograms and pounds. Cement bag size is configurable (e.g., 50 kg, 25 kg, or 94 lb).
About ratio (parts). Mixes such as 1:2:3 indicate the proportion of cement : sand : aggregate. In the “By Volume” workflow these parts split the concrete volume into constituent material volumes; in the “By Weight” workflow they split total concrete mass into material masses.
About water–cement ratio (w/c). The water mass is computed as a fraction of cement mass (e.g., w/c = 0.50 → water = 0.5 × cement). Adjusting w/c affects strength, workability, and shrinkage; always align with your specification and trial mixes.
About densities. Typical bulk densities used for “By Volume” are: cement ≈ 1440 kg/m³, sand ≈ 1600 kg/m³, and coarse aggregate ≈ 1500 kg/m³. For “By Weight”, a fresh concrete density (often 2300–2450 kg/m³; default 2400 kg/m³) converts concrete volume to total mass before parting it by proportions. Update these values to match your materials and moisture condition.
About workflows. Use By Volume when batching to buckets, boxes, or site pans (parts applied to volume, then converted to mass with bulk densities). Use By Weight for design/plant batching (parts applied directly to total mix mass from fresh density). Switching workflows immediately recomputes with your inputs preserved.
Calculation. The method allocates either volume or mass to each constituent based on the selected ratio, then derives water from the specified w/c and counts cement bags from the chosen bag size. In the “By Volume” route, parts divide the concrete volume and each material volume is multiplied by its bulk density to obtain mass. In the “By Weight” route, the concrete volume is first converted to total mass using fresh concrete density, which is then distributed to cement, sand, and aggregate according to the ratio. Finally, water mass equals w/c times cement mass, and number of bags equals cement mass divided by bag mass.
Formulas.
- Total parts = pc + ps + pa (parts sum)
- By Volume: Vi = (pi/∑p) · Vconc; mi = ρi · Vi (constituent volumes → masses)
- By Weight: Mtot = ρconc · Vconc; mi = (pi/∑p) · Mtot (total mass → constituent masses)
- mwater = (w/c) · mcement (water mass)
- Bag count = mcement / mbag (cement bags)
Examples.
- By Volume. V = 1.00 m³, parts 1:2:3, ρc=1440, ρs=1600, ρa=1500 kg/m³, w/c = 0.50, bags = 50 kg:
mcement ≈ 240 kg, msand ≈ 533 kg, magg ≈ 750 kg, mwater ≈ 120 kg, bags ≈ 4.8. - By Weight. V = 2.00 m³, ρconc=2400 kg/m³, parts 1:2:3, w/c = 0.50, bags = 25 kg:
Mtot=4800 kg → mcement ≈ 800 kg, msand ≈ 1600 kg, magg ≈ 2400 kg, mwater ≈ 400 kg, bags ≈ 32. - By Volume (imperial volume). V = 10.0 yd³, parts 1:2:4, ρc=1440, ρs=1600, ρa=1500 kg/m³, w/c = 0.45, bag = 94 lb (≈42.64 kg):
V ≈ 7.646 m³ → mcement ≈ 1573 kg, msand ≈ 3495 kg, magg ≈ 6553 kg, mwater ≈ 708 kg, bags ≈ 36.9.
Corresponding tools.
Concrete Volume Calculator,
Cement Bag Calculator,
Mortar Quantity Calculator,
Block Wall Estimator,
Bending Stress Calculator,
Beam Load Calculator.
