# Concrete Cost Calculator: Ready-Mix vs Bagged

> Work out how much concrete a slab needs, what it costs delivered by truck, and what the same pour costs in bags. All prices are your own inputs, so the result reflects your area.

**Quick answer:** A 12 × 24 ft slab poured 4 inches thick needs 3.56 cubic yards of concrete, or about 3.9 with 10% waste, so you would order roughly 4 cubic yards. At $165 per yard that is about $660 before delivery and short-load fees. Enter your own local price.

_Last updated: October 3, 2026. Estimates only; confirm quantities with your supplier._

## How concrete is priced

Ready-mix is sold by the cubic yard, and a delivery usually also carries a delivery charge and, for small orders, a short-load fee. Bagged mix is sold by the bag. This calculator turns your slab size into both totals so you can compare them using prices from your own area.

```
cubic yards = length (ft) × width (ft) × thickness (in) ÷ 12 ÷ 27
ready-mix total = ordered yards × price per yard + delivery + short-load fee
bags = cubic feet × (1 + waste) ÷ 0.6, at about 0.60 cu ft per 80-lb bag
```

### Worked example

A 12 × 24 ft slab, 4 inches thick: 12 × 24 × (4 ÷ 12) ÷ 27 = **3.56 cubic yards**. With 10% waste that is 3.91, and rounded up to the next quarter yard you order 4.00 cubic yards. At an example price of $165 per yard the concrete is **$660** before any fees. The same pour in 80-lb bags is about 176 bags.

### Cost by slab size

Volume with 10% waste, rounded up to a quarter yard, and the concrete cost at $165 per yard. Change the price to match your supplier.

| Slab | Yards to order | Concrete at $165/yd³ |
| --- | --- | --- |
| 10 × 10 ft, 4 in | 1.50 | $248 |
| 10 × 20 ft, 4 in | 2.75 | $454 |
| 12 × 24 ft, 4 in | 4.00 | $660 |
| 20 × 20 ft, 4 in | 5.50 | $908 |
| 24 × 24 ft, 4 in | 8.00 | $1320 |

### When are bags cheaper?

For very small jobs, such as a post, a step or a small pad, bags avoid delivery and short-load charges. As volume grows, mixing dozens of bags by hand is slow and the batches vary, so ready-mix usually wins past a cubic yard or two. Compare both totals above and then call two or three local suppliers for the delivered price on your exact volume.

### What this does not include

- Base gravel: use the [gravel calculator](../gravel-calculator/).
- Reinforcement (rebar or mesh), forms and expansion joints.
- Labor, pump truck or wheelbarrow rental, sealing and finishing.
- Permits, where required.

For other shapes such as footings, columns and steps, use the full [concrete calculator](../concrete-calculator/). To convert between volume units, see the [cubic yard calculator](../cubic-yard-calculator/).

## Frequently asked questions

### How much does concrete cost per cubic yard?

Prices vary by region, mix strength and delivery distance, so use a local quote. The calculator starts with $165 per yard purely as an example.

### How much concrete do I need for a 12 x 24 slab?

A 12 × 24 ft slab 4 inches thick needs 3.56 cubic yards, or about 3.9 with 10% waste.

### Is it cheaper to mix concrete from bags?

For small jobs it often is, because you avoid delivery and short-load fees. For larger pours, ready-mix usually saves time and gives a more consistent mix.

### What is a short-load fee?

A charge many ready-mix suppliers add when an order is below their minimum, to cover the truck trip. Ask your supplier for theirs.

### Does the price include labor?

No. The totals cover only the concrete itself. Labor, forms, base, reinforcement and finishing are separate.

## Sources and further reading

- [NIST Special Publication 811: conversion factors](https://www.nist.gov/pml/special-publication-811/nist-guide-si-appendix-b-conversion-factors) — National Institute of Standards and Technology