Concrete Mixer Loads Converter — How Many Mixer Loads Do I Need?

This calculator converts a total concrete volume (in m³) into the number of individual mixer loads based on your mixer type and its usable output capacity.

Mixer Output Capacities

“Mini”, “half-bag” and “full-bag” are informal trade categories rather than standardised sizes, so the figures below are typical approximations — always check your own mixer’s rated mixing capacity.

• Mini Mixer (~90L drum): ~60 litres usable output per load
• Half-Bag Mixer (~130L drum): ~90 litres usable output per load (this matches a real Belle Minimix 130/150)
• Full-Bag Mixer (~180L drum): ~130 litres usable output per load (a larger site mixer, not a Belle Minimix)
• Barrow Mix (hand): ~40 litres per batch

Standard C20 Concrete Mix (1:2:4)

The materials are calculated using a standard C20 general purpose mix ratio of 1 part cement to 2 parts sharp sand to 4 parts coarse aggregate (20mm), by volume. Applying the usual dry-volume factor of ~1.54 to the wet concrete volume, each cubic metre requires approximately:

• ~320 kg of cement = about 13 bags of 25 kg (≈ 6.5 bags of 50 kg)
• 0.45 m³ of sharp sand (~720 kg at ~1,600 kg/m³)
• 0.9 m³ of 20mm aggregate (~1,575 kg at ~1,750 kg/m³)

Time Estimates

Mixing time per load varies by mixer — as a rough rule of thumb, allow ~8 minutes for a mini mixer, ~7 minutes for a half-bag, ~6 minutes for a full-bag and ~5 minutes for a barrow mix. These are approximate mixing-only times — total time per batch including loading, pouring and cleaning will be longer.