Enter the size of your slab and your local prices to compare ready-mix delivery with bags mixed on site. Add base, reinforcement and labor to see the full cost of the job.
Other costs (both options)
| Ready-mix | Bags |
|---|
Prices vary a lot by area and season. Use quotes from your local suppliers for an accurate estimate.
What the calculator compares
- Ready-mix: cubic yards × price per cubic yard, plus delivery and any short-load fee.
- Bags: number of bags × price per bag, plus mixer rental.
- Costs for both: gravel base and forms, rebar or mesh, and labor per square foot.
The calculator doesn’t fill in prices, because they vary a lot from place to place. Call your local ready-mix plant and check bag prices at your store.
Worked example
A 12 ft × 12 ft slab, 4 inches thick, with 10 percent extra, needs 1.96 cubic yards, or 88 bags of 80 lb. Using example prices:
| Ready-mix | Bags | |
|---|---|---|
| Concrete | $313 (at $160 per yard) | $572 (at $6.50 per bag) |
| Delivery, fees or mixer | $150 | $60 |
| Total | $463 | $632 |
In this example, ready-mix comes out $169 cheaper, and it saves lifting and mixing 88 heavy bags. These prices are only for illustration.
When bags make sense
- Small pours, such as a few post holes, a step or a small pad.
- Places a concrete truck can’t reach.
- Jobs you want to do in stages over several days.
For anything over about a cubic yard, ready-mix is usually easier and often cheaper. A cubic yard takes 45 bags of 80 lb, which is about 3,600 pounds to lift and mix.
Short-load fees
Many ready-mix suppliers charge an extra fee when an order is smaller than their minimum load. Ask about it when you get a quote, and enter it under “Delivery and short-load fees” so the comparison is fair.
Other costs to plan for
- A compacted gravel base. The crushed stone calculator works out how much you need.
- Forms, stakes and screeds.
- Reinforcement. The rebar calculator works out the bars.
- Finishing labor, if you hire someone.
- Removing an old slab, and permits where needed.
Frequently asked questions
How much does a yard of concrete cost?
It varies by region, mix and season. Call one or two local ready-mix plants for a price per cubic yard and enter it above.
How much concrete do I need for a 12 × 12 slab?
At 4 inches thick, about 1.78 cubic yards, or 1.96 cubic yards with 10 percent extra. That’s 88 bags of 80 lb if you mix it yourself.
Is it cheaper to mix my own concrete?
For small jobs, often yes, because you avoid delivery fees. For larger slabs, ready-mix is usually cheaper per cubic yard and far less work.
What is a short-load fee?
An extra charge some ready-mix suppliers add when you order less than their minimum load.
Does the estimate include labor?
Only if you enter a labor price per square foot under “Other costs”. Leave it at zero if you’re doing the work yourself.
Results are estimates for planning. Prices vary by area, so use local quotes. See How We Calculate for the formulas and values we use.