How to calculate it yourself
Cubic yards = (length × width × thickness in feet) ÷ 27. For thickness in inches, divide by 12 first to convert to feet. 80 lb bags yield 0.6 ft³ each; 60 lb bags yield 0.45 ft³. Always add 10% for waste and form-pour spillage.
Common scenarios
Bagged DIY (no truck access)
Buy 60 bags of 80 lb pre-mix ($310-360 in 2026). Rent a mortar mixer ($60/day) — hand-mixing 60 bags takes 8+ hours and the joints between batches are weak. Plan a full Saturday with one helper.
Short-load ready-mix delivery
Order 1.5 yd³ to allow for waste. Total: $190-260 concrete + $80-150 short-load fee = $270-410. Half a day of work, single continuous pour, smoother finish than bagged.
Combined order with neighbor
If a neighbor is also pouring (driveway, patio), combine orders to clear the 3 yd³ minimum and skip the short-load fee. Two 1.5 yd³ slabs = 3 yd³ = no surcharge, saves $80-150.