以下のガイドはまだ日本語に翻訳されていないため、英語で表示しています。計算機自体はすべて日本語に対応しています。
この計算機の使い方
- Choose US or metric units and the shape (slab/footing or round column).
- Enter the dimensions. Slab thickness is in inches or centimeters; a typical patio or walkway slab is 4 in (10 cm).
- Enter how many identical pours you need and a waste allowance (5–10% is common for spillage and uneven ground).
計算式
Volume is length × width × thickness for slabs, and π × radius² × height for columns. Bag counts divide the total by the typical yield of each bag size.
Slab: V = L × W × T
Column: V = π × (D/2)² × H
1 yd³ = 27 ft³ = 0.7646 m³
80 lb bag ≈ 0.6 ft³; 60 lb ≈ 0.45 ft³; 40 lb ≈ 0.3 ft³
Example
- 10 ft × 10 ft slab, 4 in (0.333 ft) thick: 33.3 ft³.
- ÷ 27 = 1.23 yd³; with 10% waste ≈ 1.36 yd³.
- That's about 62 bags of 80 lb premix, so ordering ready-mix may be more practical.
よくある質問
When should I order ready-mix instead of bags?
For more than about 1 cubic yard (0.75 m³), a ready-mix truck is usually cheaper and easier than mixing dozens of bags. Ask suppliers about minimum orders.
How thick should a slab be?
Patios and walkways are often 4 in (10 cm). Driveways typically use 5–6 in (12–15 cm). Follow local codes and engineer requirements for structural slabs.
Why add a waste allowance?
Subgrades are rarely perfectly flat, forms flex, and some concrete is always lost. Running short mid-pour can create a weak cold joint.