Around a house, the “bags or truck?” decision usually happens in a driveway, a garage, or the aisle at a home center. A few fence posts feel simple. A patio pad feels less simple once the calculator says 60, 90, or 200 bags. The math matters, but so do your back, your mixer, the weather window, and whether a truck can reach the forms.
The short version
Bagged concrete is usually the practical choice for small pours, scattered post holes, repairs, and jobs where a truck cannot get close. Ready-mix starts to make sense when the bag count gets high enough that mixing, moving, and placing the concrete becomes the real project.
| Job situation | Usually easier route | Why |
|---|---|---|
| Fence posts, mailbox posts, small patch work | Bagged concrete | Small volume, flexible timing, no delivery coordination. |
| Small slab or shed pad | Depends on bag count | Bags can work, but mixing speed and help on site matter. |
| Driveway panel, large patio, thick slab | Ready-mix | Consistent batch, faster placement, less hand mixing. |
| Backyard with tight gate or no truck access | Often bagged or wheelbarrowed ready-mix | Access can override the cheapest material route. |
Start with cubic yards, not vibes
First calculate the volume. For a slab, multiply length by width by thickness in feet, then divide by 27 to get cubic yards. Add a waste allowance for uneven base, slight over-digging, form movement, and spilled material.
A common 10 ft by 10 ft slab at 4 inches thick is about 1.23 cubic yards before waste. With the default 10% waste used in our calculator, it is about 1.36 cubic yards. That is roughly 62 bags of 80 lb concrete mix, using a 0.60 cubic foot per bag planning yield.
Where bagged concrete starts to hurt
A bag count is not just a price number. It is also loading, unloading, staging, mixing, placing, and cleanup. Sixty 80 lb bags is 4,800 lb before water. That is not a casual errand unless you have a trailer, a plan, and help.
- Check whether your vehicle can safely carry the weight.
- Plan where bags will sit so they stay dry and close to the mixer.
- Think about mixer output. A small rental mixer may not keep up with a large slab.
- Keep the pour continuous enough that one batch does not set while the next is still being mixed.
Ready-mix has its own fine print
Ready-mix is not automatically cheaper or easier. Many areas have delivery fees, short-load fees, minimum orders, fuel charges, or limited Saturday slots. The truck also needs access. If the chute cannot reach the forms, you may need wheelbarrows, a concrete buggy, extra labor, or a pump.
For a front driveway panel, ready-mix can be straightforward. For a backyard slab behind a narrow gate, the delivery may be the easy part and the last 60 feet may be the hard part.
A practical cutoff
There is no universal cutoff, but many DIYers start reconsidering bags somewhere around 40 to 60 bags of 80 lb mix. Below that, bags can be manageable with a helper and a mixer. Above that, the labor and timing risk rise fast.
Use the calculator result as a first pass, then call local suppliers. Ask about minimum yardage, short-load fees, delivery windows, and whether they can place the truck where you need it. A local quote often changes the decision more than the national average price.
Use this checklist before buying
- Calculated cubic yards with your own waste allowance.
- 80 lb bag count and total bag weight.
- Vehicle or delivery plan for bagged material.
- Mixer plan, water access, and enough help to keep the pour moving.
- Ready-mix minimum order, delivery charge, and access to forms.
- Backup plan if the weather changes or the job runs late.
Bottom line
Bagged concrete wins when the job is small, spread out, or hard for a truck to reach. Ready-mix wins when the volume is large enough that consistency and placement speed matter more than the bag price. Run the numbers first, then check the local delivery details before you commit.