An 8 in Sonotube 4 ft long holds 1.4 cu ft of concrete — 3 × 80-lb bags or 4 × 60-lb bags.
| Per column | 60-lb | 80-lb |
|---|---|---|
| This calculator (geometry) | 4 | 3 |
| Quik-Tube data sheet | 4 | 3 |
| Sonoco Sonotube table | 4 | 3 |
| Bag | Bags | Est. cost |
|---|---|---|
| 40 lb · 0.3 ft³ | 6 | — |
| 50 lb · 0.375 ft³ | 5 | — |
| 60 lb · 0.45 ft³ | 4 | $19.40 |
| 80 lb · 0.6 ft³ | 3 | $19.41 |
Typical U.S. big-box prices checked 2026. Tap any price to enter your store's.
| Length | Cu ft per tube | 80-lb per tube | 60-lb per tube |
|---|---|---|---|
| 2 ft | 0.7 | 2 | 2 |
| 3 ft | 1.05 | 2 | 3 |
| 4 ft ← | 1.4 | 3 | 4 |
| 5 ft | 1.75 | 3 | 4 |
| 6 ft | 2.09 | 4 | 5 |
| 8 ft | 2.79 | 5 | 7 |
Round forms are cylinders: area = π × radius². An 8 in tube has a 4 in radius, so π × 4² = 50.3 sq in ÷ 144 = 0.349 sq ft. Multiply by the length in feet for cubic feet.
1.4 cu ft ÷ 0.6 cu ft per 80-lb bag = 2.33, and ÷ 0.45 per 60-lb bag = 3.1. Tube tables round each tube up — here that leaves most of a bag over, so on several tubes round the total instead.
At 0.06 yd³ this is a bag job: a truck's 1 yd minimum plus fees would cost about $485.
The full method, material data and tips are on the main sonotube & column concrete calculator page.