Construction
Calculatrice vérifiée avec une formule transparente
Concrete Patio Calculator.
Estimates the volume of concrete needed for a rectangular patio slab and the number of 80 lb bags required.
Vos entrées
Comment ça marche
- 1
Measure the length and width of the patio in feet.
- 2
Decide on the slab thickness in inches (typically 4 inches).
- 3
Multiply length × width × (thickness ÷ 12) to get cubic feet.
- 4
Divide by 0.6 (cubic feet per 80 lb bag) and round up for bags.
length * width * (thickness / 12)Questions fréquentes
How many cubic feet does an 80 lb bag of concrete cover?
An 80 lb bag of concrete mix yields about 0.6 cubic feet when mixed.
What thickness should I use for a patio?
A standard patio slab is 4 inches thick. For heavier loads, consider 5-6 inches.
Should I order extra concrete?
It's wise to add 5-10% extra to account for waste, spillage, or uneven subgrade.
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Résultats
Formule vérifiéeEstimation à titre indicatif uniquement — vérifiez les décisions importantes avec un professionnel approprié.
Comment ça marche
Estimates the volume of concrete needed for a rectangular patio slab and the number of 80 lb bags required.
- Measure the length and width of the patio in feet.
- Decide on the slab thickness in inches (typically 4 inches).
- Multiply length × width × (thickness ÷ 12) to get cubic feet.
- Divide by 0.6 (cubic feet per 80 lb bag) and round up for bags.
Formules
Les mathématiques derrière cette calculatrice, écrites pour que vous puissiez vérifier le résultat.
Volume of a rectangular slab
Multiply length, width, and thickness (converted to feet) to get cubic feet.
Example:
Input: L=12 ft, W=10 ft, T=4 in
Calculation: 12 × 10 × (4/12) = 40 cu ft
Result: 40 cubic feet
Bags of concrete
Each 80 lb bag yields about 0.6 cubic feet, so divide volume by 0.6 and round up.
Example:
Input: V=40 cu ft
Calculation: 40 / 0.6 = 66.67 → 67 bags
Result: 67 bags
Cas d'utilisation réels
Où ce calcul apparaît dans la vie quotidienne.
Planning a new patio
Estimate concrete volume and bag count before purchasing materials.
Example: A 12×10 ft patio at 4 inches thick needs 40 cu ft, about 67 bags.
Comparing ready-mix vs bagged
Use the volume to get quotes from ready-mix suppliers or calculate bag costs.
Example: For 150 cu ft, ready-mix might be more economical than 250 bags.
Budgeting for a DIY project
Know exactly how many bags to buy and the total cost.
Example: At $5 per bag, 67 bags cost about $335.
Conseils et erreurs courantes
Tips
- Add 5-10% extra volume for waste and spillage.
- Check local building codes for minimum thickness requirements.
- Prepare a level, compacted subgrade to avoid uneven settling.
- Use a concrete calculator for irregular shapes by breaking them into rectangles.
Common Mistakes to Avoid
- Forgetting to convert thickness from inches to feet.
- Not rounding up bag count, leading to a shortage.
- Ignoring waste and ordering exactly the calculated amount.
Hypothèses et limites
- Use the stated inputs and units.
- Results are estimates for planning and education.
- Check measurements and source data before making an important decision.