What densities are used for the materials?

The calculator assumes 1440 kg/m^3 for cement, 1536.491 kg/m^3 for sand and 1589.98066 kg/m^3 for gravel, matching common bulk-density references.

Why is the dry-ingredient volume 54 % higher than the finished volume?

Extra volume accounts for air spaces between sand and aggregate particles before compaction. A 1.54 multiplier is standard practice for on-site batching.

Is the water-to-cement ratio entered by weight or volume?

Enter the w/c ratio by weight. For example, 0.50 means 0.50 kg of water for each kilogram of cement.

Can I use non-integer mix ratios (e.g. 1 : 1.5 : 2.8)?

Yes. Enter any positive decimal for each part value; the calculator scales volumes and weights automatically.

Spike's Calculators

Metric Concrete Mix Ratio Calculator

Self Mix Concrete Calculator. AI generated image

The Metric Concrete Mix Ratio Calculator determines the exact amounts of cement, sand, gravel, and water needed to produce a specified volume of concrete when working in metric units and kilograms.

How it works

Mixing ratio - Enter the number of "parts" for cement, sand and gravel (e.g. 1 : 2 : 3)
Water-to-cement ratio (w/c) - Supply the ratio by weight (typical range 0.35-0.65)
Concrete Volume: Provide the finished volume required in cubic meters

The calculator adds a 54 % bulking factor to turn the finished volume into dry-ingredient volume, allocates that volume to each component according to the ratio, and converts each component to weight using standard bulk densities (cement 1440 kg/m³ sand 1536.491 kg/m³ gravel 1589.98066 kg/m³) and finally computes water by multiplying the w/c ratio by the cement weight.

Use the outputs to order materials or check on-site volumes before mixing.

Self-Mix Metric Calculator

Mixing Ratio
Cement # Sand # Gravel #

Cement/Water Ratio

Volume of Concrete Needed

m³

Results:
Dry Volume of the Ingredients	m³
Volume and Weight of Cement	m³ kg
Volume and Weight of Sand	m³ kg
Volume and Weight of Gravel	m³ kg
Water m³ kg litres
Total Weight	kg

Calculator

enter the cement, sand, and gravel ratio for the concrete mix
the cement-to-water ratio
the volume of concrete required in cubic meters

Results

volume of the dry materials in cubic metres
the volume in cubic metres and the weight in kilograms of the cement
the volume in cubic metres and the weight in kilograms of the sand
the volume in cubic metres and the weight in kilograms of the gravel
the water volume in cubic meters, its weight in kilograms, and the volume in litres
the total weight of the concrete mix in kilograms

Self-Mix Concrete - Calculation Formulas

$$P = c + s + g$$ $$V_d = V \times 1.54$$ $$V_c = \dfrac{c}{P}\,V_d \qquad V_s = \dfrac{s}{P}\,V_d \qquad V_g = \dfrac{g}{P}\,V_d$$ $$M_c = V_c \times 1440$$ $$M_s = V_s \times 1536.491$$ $$M_g = V_g \times 1589.98066$$ $$M_w = \left(\dfrac{w}{c}\right) M_c \qquad V_w = \dfrac{M_w}{1000}$$ $$M_{\text{total}} = M_c + M_s + M_g + M_w$$

Worked Example

Mix ratio 1 : 2 : 3 (c : s : g),
water-to-cement ratio w/c = 0.50 (by weight),
required concrete volume V = 1 m³.

Step	Equation	Result
Total parts	$P = 1+2+3$	6
Dry volume	$V_d = 1 \times 1.54$	1.54 m³
Cement volume	$V_c = \frac16 \times 1.54$	0.257 m³
Sand volume	$V_s = \frac26 \times 1.54$	0.513 m³
Gravel volume	$V_g = \frac36 \times 1.54$	0.770 m³
Cement mass	$M_c = 0.257 \times 1440$	369.6 kg
Sand mass	$M_s = 0.513 \times 1536.491$	789.5 kg
Gravel mass	$M_g = 0.770 \times 1589.98066$	1225.1 kg
Water mass	$M_w = 0.50 \times 369.6$	184.8 kg
Water volume	$V_w = 184.8 / 1000$	0.185 m³
Total mix weight	$M_{\text{total}} = 369.6 + 789.5 + 1225.1 + 184.8$	2569 kg

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