Ready-mix vs bagged concrete

Bagged premix wins on small pours, ready-mix wins on big ones, and the line between them is a number you can solve. Enter your local prices and this finds the break-even volume — plus the weight you'd move by hand if you went bagged.

01 How the math works

Bagged and ready-mix scale differently, and that difference is the whole comparison. Bagged cost is a straight line through zero: every cubic yard is a fixed number of bags at a fixed price. Ready-mix cost is a line that starts above zero, because most suppliers add a flat short-load fee on small orders.

Bags per yard is set by the bag yield, not the bag weight. A standard 80 lb bag yields 0.60 ft³, so a cubic yard (27 ft³) takes 45 bags. The 60 lb bag takes 60, the 40 lb bag takes 90. Multiply by your bag price to get bagged cost per yard.

The break-even is where the two totals meet. Below it, bagged is cheaper because it dodges the fee. Above it, ready-mix is cheaper because its per-yard rate is lower. If bagged already costs more per yard than ready-mix — which is common — the fee is the only reason to ever choose bags, and the crossover is small.

02 Worked example

Take a backyard patio slab, 10 ft × 12 ft × 4 in (3.05 m × 3.66 m × 100 mm). The raw volume is 40 ft³ = 1.48 yd³ = 1.13 m³. Add a 10% waste factor before ordering either way.

Bagged, at the 80 lb yield of 0.60 ft³: 74 bags with waste, which is 5,920 lb (2,685 kg) of dry mix to open and mix by hand. Ready-mix rounds up to the half-yard step at 2.0 yd³ (1.5 m³), and since that clears the 1 yd³ short-load threshold, no fee applies.

Now the money — and these prices are the example figures in the widget, not quotes from anyone; swap in your own. At $5 a bag, bagged runs $370. At $160/yd³, ready-mix runs $320. Ready-mix is $50 cheaper here, and the break-even those same prices produce is 1.85 yd³ (1.41 m³). This pour sits just past it, which is exactly why the truck edges out the bags.

03 When this calculator is wrong

The cost side is only as good as the two prices you feed it, and concrete pricing is regional and moves with fuel and cement costs. Treat the pre-filled figures as placeholders. Two things bend the answer even after the prices are right:

• The labor ceiling caps bagged before cost does. A cubic yard is 45 × 80 lb bags — 3,600 lb (1,633 kg) of dry product to lift, cut open, hydrate, and mix, batch by batch, before it starts setting in the mixer. Our position (O3) is that bagged stops making sense above about 1 yd³ (0.76 m³) on labor alone, whatever the spreadsheet says. The exception is access: if the truck can't reach the form — a remote backyard, a basement, a second-storey balcony — bagged or pumped is the only option at any volume.
• The short-load threshold and fee vary by supplier. The calculator assumes the fee applies below 1 yd³, which is the common trigger, but some yards set it at 2 yd³ and the fee itself typically runs $50–150. A different threshold shifts the crossover. Call two suppliers before you commit — the second quote is free.
• Bag yield is a spec-sheet figure. Real placed yield from an 80 lb bag runs 0.55–0.60 ft³ depending on how much water went in. The calculator uses the published 0.60; if you're mixing wet, your true bag count is a little higher and bagged looks a little worse.
• It ignores the value of your time. Mixing 74 bags is most of a day for one person. The comparison here is materials only — it doesn't price the hours, the mixer rental, or the cleanup.

04 What to do with the result

Read the break-even against your pour. If the volume you need is comfortably below the crossover and under about 1 yd³, buy bags — the count in the widget is your shopping list, rounded up. If it's above the crossover, or above 1 yd³ regardless of the crossover, order ready-mix at the rounded-up figure and let the truck do the lifting.

When the pour lands near the line, the tiebreaker isn't price. It's the 3,600 lb per yard you'd move by hand versus a 20-minute chute. Order the rounded-up number either way — concrete can't be topped up mid-pour, and finishing a slab short is a mistake you make once.

05 Common questions

Is it cheaper to mix your own concrete or buy ready-mix?

On material cost alone, bagged is usually cheaper on small pours because it avoids the short-load fee, and ready-mix pulls ahead as volume grows. The break-even is the fee divided by the per-yard price gap. Enter both prices above and the calculator solves it — but for anything over about 1 yd³, the 3,600 lb of bags per yard usually settles it before cost does.

How many bags of concrete equal a yard of ready-mix?

A cubic yard is 45 of the 80 lb bags, 60 of the 60 lb bags, or 90 of the 40 lb bags — all standard mix. That's 3,600 lb of dry product any way you slice it, because every standard normal-weight mix yields the same 0.0075 ft³ per pound.

What is a short-load fee?

A flat charge ready-mix suppliers add to orders under a minimum volume — commonly 1 yd³, sometimes 2 — to cover sending a truck out for a partial load. It typically runs $50–150 and is the single biggest reason bagged stays competitive on very small pours.

At what volume should I switch from bags to ready-mix?

Cost break-even depends on your local prices, but the practical answer is about 1 yd³ (0.76 m³). Below that, bags are manageable and often cheaper. Above it, you're hand-mixing more than 45 bags, and ready-mix wins on time, uniformity, and usually cost.

Does the bag size change the cost comparison?

Yes. The 80 lb bag is the cheapest per cubic foot of the three standard sizes, so it gives bagged its best shot against ready-mix. Smaller bags cost more per yard of coverage, which pushes the break-even lower. The bag-size field lets you test each.