Curb
A 100 ft run of curb-and-gutter: a 6 in × 18 in curb with a 12 in × 4 in gutter pan. Both cross-sections are added before multiplying by the run. That is 108.33 cubic feet, or 4.01 cubic yards: 181 bags of 80 lb premix or 241 bags of 60 lb, before any waste.
Concrete needed
| Bag size | Bags needed |
|---|---|
| 40 lb | 362 |
| 60 lb | 241 |
| 80 lb | 181 |
| 25 kg | 263 |
| 30 kg | 219 |
Same job, other sizes
Each foot of this curb and gutter holds 1.08 ft³, so one cubic yard pours about 24.9 ft of it.
One 80 lb bag fills about 7 in of run.
Change the dimensions in the curb calculator. Why every count rounds up: how many bags of concrete you need.
At this size
181 × 80 lb bags is 4.01 yd³ - about 91 mixer batches. At this size the bag count is a costing reference rather than a plan: mixing 181 bags on site cannot keep ahead of the setting edge, so the pour ends up full of cold joints. Ordered by the yard it is part of a single load. Have the crew, the access and the discharge points sorted before anything arrives.
| Run | 100 ft |
|---|---|
| Curb | 6×18 in |
| Gutter | 12×4 in |
A curb is a long prism: its cross-section (width × height) times the run. For curb-and-gutter, the flat gutter pan (width × thickness) is added to the cross-section before multiplying by the length.
That volume - 108.33 ft³ - is divided by 27 to give 4.01 cubic yards, and by each bag's yield to give the bag count. An 80 lb bag of premix yields about 0.60 cubic feet, so this job takes 181 of them; bag counts always round up, because you cannot buy part of a bag.
Ordering ready-mix instead? Suppliers sell by the cubic yard (or cubic metre) and usually have a minimum load and a short-load surcharge - worth a call before you choose between bags and a truck.
Formwork
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