Concrete Bag Calculator
Wondering how many bags of concrete you need? This concrete bag calculator turns dimensions into an exact number of bags for every common size — kg bags (20, 25, 30, 40) and lb bags (50, 60, 80, 90) — with waste allowance built in.
Come usare questa calcolatrice
- Inserisci le tue dimensioni — piedi per le lunghezze, pollici per lo spessore.
- Regola le opzioni — percentuale di sfrido, dimensione del sacco e il prezzo locale del calcestruzzo.
- Leggi i risultati — volume, sacchi, peso e costo si aggiornano in tempo reale mentre digiti.
La formula
Number of bags = volume ÷ yield per bag, rounded up. Yields: 80 lb ≈ 0.60 ft³, 60 lb ≈ 0.45 ft³, 50 lb ≈ 0.375 ft³, 25 kg ≈ 12.5 L, 20 kg ≈ 11 L Esempio svolto: A 10 × 10 ft slab at 4 in = 33.3 ft³. In 80 lb bags: 33.3 ÷ 0.60 = 56 bags. In 60 lb bags: 74. With 5% waste: 59 and 78.
The concrete calculator in bags mode answers the checkout-line question directly: results show the number of bags for your selected size, already rounded up. Switch sizes to compare — the price per cubic foot varies more than people expect (larger bags are almost always cheaper per volume).
For a concrete bag calculator kg users trust: metric bag yields are ≈ 11 L per 20 kg, 12.5 L per 25 kg and 15 L per 30 kg — so a cubic meter takes about 91 × 20 kg bags or 80 × 25 kg bags.
Quick benchmarks: one cubic yard = 45 × 80 lb bags = 60 × 60 lb = 72 × 50 lb. One fence post hole (12 in × 24 in) ≈ 3 × 80 lb bags. A 4 × 8 ft pad at 4 in ≈ 18 × 80 lb bags.
Domande frequenti
Domande comuni sulla concrete bag calculator.
How many bags of concrete do I need for a 10×10 slab?
At 4 inches thick: 33.3 ft³ = 56 × 80 lb bags, 74 × 60 lb bags, or 89 × 50 lb bags — add 5–10% waste on top.
How many bags make a cubic yard?
45 × 80 lb, 60 × 60 lb, or 72 × 50 lb bags. In metric: about 91 × 20 kg or 80 × 25 kg bags per cubic meter.
Which bag size is most economical?
Bigger bags cost less per cubic foot — 80 lb bags are usually the best value if you can lift them. 60 lb splits the difference; 50 lb suits smaller batches and mixing by hand.
When should I stop using bags and order ready-mix?
Around 1 cubic yard (45+ bags). Beyond that, a ready-mix truck is typically cheaper, faster and produces more consistent concrete.
Calcolatrici correlate
Altri strumenti della famiglia di calcolatrici per calcestruzzo.