3 concrete steps 4 ft wide with a 36 in landing take 27.4 cu ft (1.02 yd³) — 51 × 80-lb bags with 10% extra.
Volume = width × [rise × tread × (n−1)·n ÷ 2 + n × rise × landing] with n = 3 step-ups: 4 ft × 987 sq in ÷ 144 = 27.42 ft³.
| Bag | Bags | Est. cost |
|---|---|---|
| 40 lb · 0.3 ft³ | 101 | — |
| 50 lb · 0.375 ft³ | 81 | — |
| 60 lb · 0.45 ft³ | 68 | $330 |
| 80 lb · 0.6 ft³ | 51 | $302 |
At these prices a truck becomes cheaper from about 3.25 yd³ (147 bags). Over 1–2 yd³, a truck also saves hours of mixing: plan on 3–4 minutes per bag in a mixer.
Typical U.S. big-box prices checked October 2026. Tap any price to enter your store's.
| Steps | Cubic yards | 80-lb bags | 60-lb bags | Bag cost | Ready-mix |
|---|---|---|---|---|---|
| 2 | 0.6 | 30 | 40 | $194 | $485 |
| 3 ← | 1.02 | 51 | 68 | $302 | $528 |
| 4 | 1.51 | 75 | 100 | $445 | $613 |
| 5 | 2.09 | 104 | 138 | $617 | $740 |
| 6 | 2.74 | 136 | 182 | $806 | $868 |
Treat each step as a solid block sitting on the ground: step 1 is one riser tall, step 2 two risers, and so on. Their side profiles add up to rise × tread × (n − 1)·n ÷ 2 = 7 × 11 × 6 ÷ 2 = 231 sq in. The landing is a full-height block: 3 × 7 × 36 = 756 sq in.
Profile 987 sq in ÷ 144 = 6.854 sq ft × 4 ft wide = 27.42 cu ft. With 10% extra, 30.16 ÷ 0.6 = 50.3 → 51 bags.
At 1.12 yd³ bags are cheaper than a truck at the default prices, but plan the crew: 51 bags (4,080 lb) have to be mixed and placed in one session so the steps bond.
The full method, material data and tips are on the main concrete steps calculator page.