About

When standing at the builder's merchant or on a job site, you rarely need a full chemical breakdown of concrete; you just need to know how many bags of cement to load onto the truck. This "Quick Check" tool isolates the binder component of the mix. It specifically addresses the Rounding Problem: calculating 4.2 bags is useless because you cannot buy partial bags. This tool forces a round-up logic to ensure you never halt a pour due to a lack of material.

It incorporates a standard M15/M20 mix assumption where cement typically constitutes 14.3% to 18% of the total dry volume, adjusted for the selected bag weight standard (European, US, or Asian markets).

Formulas

We utilize the M20 (1:1.5:3) volumetric ratio as the standard default for durable concrete.

Vol_cement = 1.54 × V1 + 1.5 + 3

Bags = ceilVol_cement × 1440BagWeight

If "Add Waste" is checked, we multiply the final bag count by 1.05 before rounding up.

Reference Data

Bag Standard	Weight	Volume Coverage (M20)
Europe / Global	25 kg	≈ 0.08 m³ concrete
Legacy / Industrial	50 kg	≈ 0.16 m³ concrete
USA Standard	42.6 kg (94 lb)	≈ 0.14 m³ concrete
Small / DIY	20 kg	≈ 0.06 m³ concrete

Frequently Asked Questions

Yes. The calculator assumes a standard M20 mix (1 part cement : 1.5 sand : 3 aggregate), which is the industry standard for domestic foundations and slabs. If you are doing structural columns, consult a structural engineer.

Cement bags break, powder blows away in the wind, and some concrete always sticks to the mixer or wheelbarrow. Professional estimators always add 5-10% to account for these unavoidable site losses.

Do not use this tool for "Premix" (Just add water) bags. This tool calculates pure cement bags assuming you are adding your own sand and gravel. For Premix, typically 108 x 20kg bags are needed for 1 cubic meter.