How many bags of concrete can you mix per hour?
The rate matters less than whether it beats the clock. Concrete starts setting in 30 to 45 minutes, and that is the real constraint on any pour.
Throughput by method
| Method | 80 lb bags/hr |
|---|---|
| Wheelbarrow and hoe | ~8 |
| Bucket and paddle mixer | ~14 |
| Drum mixer, 3.5 cu ft | ~20 |
| Continuous auger mixer | 45+ |
One cubic yard is about 45 × 80 lb bags or 60 × 60 lb bags.
On this page
The question is usually asked as a scheduling problem — how long will this take? — but the number that actually matters is different. What you need to know is whether your mixing rate beats concrete's set time.
The rates, honestly
Per 80 lb bag, sustained over an hour, one person:
| Method | Bags/hr | Cubic ft/hr | Cubic yd/hr |
|---|---|---|---|
| Wheelbarrow and hoe | 8 | 4.8 | 0.18 |
| Bucket and paddle mixer | 14 | 8.4 | 0.31 |
| Drum mixer, 3.5 cu ft | 20 | 12 | 0.44 |
| Drum mixer, 6 cu ft | 28 | 16.8 | 0.62 |
| Continuous auger mixer | 45 | 27 | 1.0 |
Two caveats on those figures. The continuous mixer's 45 assumes someone is feeding the hopper without pause — working alone, it is nearer 30. And the hand-mixing figure of 8 holds for the first hour and declines after that, because mixing concrete with a hoe is genuinely hard work.
Converting to bags
Yield per bag, mixed:
| Bag size | Yield | Bags per cubic yard |
|---|---|---|
| 40 lb | 0.30 cu ft | 90 |
| 50 lb | 0.375 cu ft | 72 |
| 60 lb | 0.45 cu ft | 60 |
| 80 lb | 0.60 cu ft | 45 |
Volume for a slab: length × width × thickness, all in feet, divided by 27 for cubic yards.
A 10 × 12 ft patio at 4 inches thick: 10 × 12 × 0.333 = 40 cubic feet = 1.48 cubic yards = 67 × 80 lb bags. Add 5 to 10% for waste, spillage and uneven subgrade, so call it 72 bags.
our concrete bag calculator does this for slabs, footings and post holes, and reports mixing time for each method.
The constraint that actually matters
Concrete begins its initial set at 30 to 45 minutes in typical conditions, and faster when it is hot — at 90 °F you may have 20 minutes.
If you place fresh concrete against concrete that has already begun setting, you get a cold joint: a plane through the slab with no aggregate interlock across it. It is a designed-in crack, and it will open.
So the real planning question is not "how long will this take" but "can I place each section before the previous one sets".
Work it out for the 67-bag patio above:
| Method | Total time | Cold joints? |
|---|---|---|
| By hand, 8 bags/hr | 8.4 hr | Guaranteed, many |
| Drum mixer, 20 bags/hr | 3.4 hr | Yes, unless sectioned |
| Continuous mixer, 45 bags/hr | 1.5 hr | Manageable with a helper |
| Ready-mix truck | 30 min | No |
That table is the argument for a faster method, and it is a quality argument rather than a convenience one. A hand-mixed 10 × 12 patio is not a slower slab, it is a worse slab.
How to work within a slow rate
If a machine is not available, you can still get a sound result by planning around the set time rather than fighting it.
Section the pour deliberately. Divide the slab into panels you can complete within 30 minutes each, and form proper construction joints between them with a bulkhead. A deliberate joint is a designed feature; an accidental cold joint is a defect. Panels of about 8 × 8 feet are usually manageable.
Pour in the morning. Cooler temperatures extend working time substantially. A 7 am start in summer is worth two extra machines.
Get a second person. One mixing and one placing roughly doubles effective throughput, because the two tasks stop competing for the same hands.
Use a retarder in hot weather. A set-retarding admixture buys 30 to 60 minutes of working time for a few dollars, and it is what commercial pours use routinely in summer.
Wet the subgrade. Dry ground pulls water out of the mix from below, accelerating set at the bottom of the slab where you cannot see it happening.
Temperature changes every number here
Every figure above assumes a mild day. Concrete does not care about your schedule and it responds strongly to temperature.
| Ambient | Working time | Effect |
|---|---|---|
| 50 °F | 60–90 min | Slow set, slow strength gain |
| 60 °F | 45–60 min | Comfortable |
| 70 °F | 30–45 min | Standard assumption |
| 85 °F | 20–30 min | Rushed; consider a retarder |
| 95 °F+ | 15–20 min | Pour early or not at all |
The chemistry is straightforward: hydration is a chemical reaction and reaction rates roughly double for every 18 °F of temperature rise. A pour that is comfortable at 8 am in July is a different job at 2 pm.
Two practical consequences. Start early in summer — a 7 am start is worth more than any equipment upgrade. And below 50 °F, strength development slows dramatically; below 40 °F it effectively stops, and concrete that freezes before it has reached about 500 psi is permanently damaged.
What to have ready before you mix the first bag
The pour is not the place to discover something is missing, because the clock starts with the first bag.
- Forms built, braced and checked square. Concrete pushes hard and a bowed form is permanent.
- Subgrade compacted and dampened. Dry ground steals water from the bottom of the slab.
- Reinforcement placed and supported off the ground on chairs, not laid on the subgrade and pulled up mid-pour, which never works.
- All tools out and wet: screed board, bull float, edger, groover, trowel, broom.
- A second person confirmed. Placing and mixing compete for the same hands.
- Water for cleaning, separate from the water for mixing.
- A plan for the joint if the volume means you cannot beat the set time.
When to stop mixing altogether
Above about 1.5 cubic yards — 68 bags — the arithmetic favours ready-mix delivery outright.
Bagged concrete runs roughly $250 to $300 per cubic yard in materials. Delivered ready-mix runs $150 to $200 per cubic yard, plus a short-load fee below about 3 yards. So at 1.5 yards you are already paying more for bags, before accounting for eight hours of your own labour and a slab full of cold joints.
The reasons to keep mixing above that volume are access — a truck cannot reach a back garden — and pour geometry that a chute cannot serve. Those are real, and they are why concrete pumps and buggies exist. But price is not one of them.
For the machine end of this, our Mud Mixer MMXR-3225 review covers what 45 bags an hour costs to own, and mixing by machine against by hand covers where the crossover between hand and machine actually falls.
Questions people actually ask
How many 80 lb bags of concrete make a yard?
About 45. Each 80 lb bag yields roughly 0.6 cubic feet of mixed concrete, and a cubic yard is 27 cubic feet. For 60 lb bags the figure is about 60 per yard, and for 50 lb bags about 72.
How long does concrete take to start setting?
Initial set begins at 30 to 45 minutes in typical conditions, and considerably faster in heat. At 90 °F you may have only 20 minutes of working time. That window — not your mixing rate — is what determines whether a pour comes out as one slab or several.
How many bags of concrete can one person mix in a day?
By hand, 40 to 50 sustainably over a working day, with the rate declining through the afternoon. With a drum mixer, 120 to 150. With a continuous mixer and someone feeding the hopper, 250 or more. The limiting factor beyond about 100 bags is usually placing and finishing rather than mixing.
Is it faster to mix two bags at a time?
In a drum mixer, yes — a 3.5 cubic foot drum handles two 80 lb bags per batch, and the mixing time per batch barely changes. In a wheelbarrow, no: two bags is more material than you can work through with a hoe in a reasonable time, and the mix quality suffers.
Does cold weather slow the pour down?
It extends the set time, which gives you more working time, and it slows strength development considerably. Below 40 °F the concrete needs protection and admixtures, and below freezing you should not be pouring at all without proper cold-weather measures.
At what point should I order ready-mix instead?
Around 1.5 cubic yards, or roughly 68 bags. Bagged mix costs $250 to $300 per cubic yard in materials against $150 to $200 delivered, so at that volume ready-mix is cheaper before you value your own labour at all. Short-load fees apply below about 3 yards but rarely change the answer.