Concrete Bag Calculator (2026) – Quikrete, Sakrete & All Sizes
Find exactly how many bags of concrete you need — 40, 50, 60, 80, and 90 lb — for slabs, post holes, or any custom volume. Includes Quikrete, Sakrete, and store-brand comparisons.
Always add 5–10% — concrete is unforgiving if you run short mid-pour
Bags Needed
Live calculation active
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40 lb bags
(0.30 ft³ each)
(0.30 ft³ each)
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50 lb bags
(0.375 ft³ each)
(0.375 ft³ each)
Most Common
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60 lb bags(0.45 ft³ each)
Best Value
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80 lb bags(0.60 ft³ each)
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90 lb bags (0.675 ft³ each) — professional/contractor packs
| Brand | Bag Size | Bags Needed | Est. Cost |
|---|---|---|---|
| Quikrete 5000 | 80 lb | — | — |
| Quikrete General | 60 lb | — | — |
| Sakrete 5000+ | 80 lb | — | — |
| Store Brand | 60 lb | — | — |
*Prices based on 2026 Home Depot/Lowe's averages. Varies by region.
Concrete Bag Yield Reference Table
Each bag size yields a different volume. Use this table to quickly estimate bag counts without a calculator:
| Bag Size | Yield (ft³) | Bags per yd³ | Approx. Price | Best For |
|---|---|---|---|---|
| 40 lb | 0.30 ft³ | 90 bags | $5.50–$7.00 | Small repairs, post holes |
| 50 lb | 0.375 ft³ | 72 bags | $6.50–$8.50 | Post holes, steps, repairs |
| 60 lb | 0.45 ft³ | 60 bags | $7.00–$9.50 | Small slabs, patios under 0.5 yd³ |
| 80 lb | 0.60 ft³ | 45 bags | $9.00–$12.00 | Best value — slabs up to 1 yd³ |
| 90 lb | 0.675 ft³ | 40 bags | $10.00–$13.50 | Contractor use — fewer trips to mixer |
💡 Rule of thumb: One 80 lb bag covers about 0.022 cubic yards. Divide your cubic yard volume by 0.022 to get the number of 80 lb bags needed (before waste factor).
Quikrete vs. Sakrete vs. Store Brand — 2026
| Brand | Popular Product | PSI | Set Time | Notes |
|---|---|---|---|---|
| Quikrete | 5000 Concrete Mix | 5,000 PSI | 24–72 hrs | Most widely available in US. High strength — great for structural work. |
| Quikrete | Fast-Setting Concrete | 4,000 PSI | 20–40 min | Pour dry into hole, add water on top. Ideal for fence posts — no mixing required. |
| Sakrete | 5000+ Concrete Mix | 5,000 PSI | 24–72 hrs | Similar to Quikrete 5000. Available at Home Depot and Lowe's. |
| Sakrete | Maximizer | 4,000 PSI | 24–48 hrs | Larger yield per bag — approximately 20% more volume than standard 80 lb bags. |
| Store Brand | Generic Concrete Mix | 3,000–4,000 PSI | 24–72 hrs | Usually 10–20% cheaper. Fine for non-structural work. Check the PSI label. |
When to Use Bags vs. Ready-Mix
For most projects under 0.75 cubic yards (about 20 cubic feet), bags are practical. Above that, ready-mix is cheaper and produces more consistent results.
- Use bags when: project is under 0.75 yd³, no truck access, working at your own pace, or for fence posts and repairs.
- Use ready-mix when: project exceeds 1 yd³, you need consistent high-strength mix, or labor cost of mixing bags would exceed delivery fee.
- Cost comparison: 80 lb bags cost ~$210–$280/yd³. Ready-mix costs $140–$225/yd³. For a 3 yd³ slab, bags cost ~$650–$840 vs. ready-mix at ~$420–$675 — plus you save hours of mixing labor.
Mixing Bagged Concrete: Step-by-Step
Getting the water-to-concrete ratio right is the most important step in working with bagged concrete. Too much water produces a weak, cracked slab; too little makes the mix hard to work and can cause honeycombing.
What You Need
- Wheelbarrow or plastic mortar tub (for small batches) — or a rented electric mixer (for 6+ bags)
- Garden hoe or mixing paddle on a drill
- Measuring container (a 1-gallon jug works well)
- Safety glasses and gloves — Portland cement is caustic
Mixing Procedure
- Add about 2/3 of the required water to the mixing container first.
- Pour in the dry concrete mix while mixing continuously.
- Add remaining water gradually until you reach a thick, oatmeal-like consistency.
- Mix for 3–5 minutes until uniform — no dry pockets, no standing water.
- Use within 30–45 minutes. Do not add more water after this window.
💡 Renting a mixer pays off fast: A drum mixer rents for $40–$80/day and can handle 3 bags at a time. For any project over 20 bags, a mixer saves 2–3 hours of labor and produces more consistent results than hand-mixing in a wheelbarrow.
Common Mistakes to Avoid
- Adding too much water — weakens the concrete by up to 30%. Stick to the label's recommended ratio.
- Mixing too small a batch — the last batch in a project often dries at a different rate, creating a visible color or texture seam.
- Pouring in cold weather — concrete below 50°F cures far slower. Below 40°F, it may not cure properly at all without additives or heating.
- Skipping the waste factor — always order 5–10% extra. Running out mid-pour on a structural project is expensive to fix.
- Not curing properly — cover fresh concrete with plastic sheeting or burlap for 3–7 days to retain moisture during curing. Dry concrete cracks.
Worked Example: How Many Bags for a 12×16 Patio?
Let's walk through a complete calculation for a 12×16 ft patio slab at 4-inch thickness:
- Volume (net): 12 × 16 × (4 / 12) = 12 × 16 × 0.333 = 63.9 ft³
- Add 10% waste: 63.9 × 1.10 = 70.3 ft³
- Convert to cubic yards: 70.3 / 27 = 2.6 yd³
- 80 lb bags needed: 70.3 / 0.60 = 118 bags
- Estimated bag cost: 118 × $10.50 = ~$1,239
- Ready-mix comparison: 2.6 yd³ × $160 + $100 short-load fee = ~$516
For this size project, ready-mix concrete costs roughly half the price of bags and eliminates 3–4 hours of mixing labor. Bags are only competitive for projects under 0.75 yd³.
Concrete Bag FAQ
How many 80 lb bags of Quikrete do I need for a 10×10 slab?
A 10×10 slab at 4 inches thick = 33.3 ft³ + 10% waste = 36.7 ft³. At 0.60 ft³ per 80 lb bag: 62 bags. At current prices (~$10/bag), that's ~$620 in bags alone. A ready-mix truck delivery of 1.36 yd³ would cost ~$220–$300 for material — plus a short-load fee. For a project this size, bags vs. ready-mix is close; ready-mix wins on labor.
How many bags of concrete for a fence post?
A standard 10-inch diameter × 24-inch deep fence post hole = 1.09 ft³. One 80 lb bag (0.60 ft³) is not quite enough — use two 80 lb bags per hole, or one 60 lb + one 40 lb bag. For 4×4 posts, a 6-inch diameter hole with one 50 lb bag per post is sufficient. Quikrete Fast-Setting Concrete is the easiest option — pour dry mix around the post and add water directly into the hole, no mixing required.
How many bags of concrete in a yard?
1 cubic yard = 27 cubic feet. Bags needed per cubic yard: 90 × 40 lb bags, 72 × 50 lb bags, 60 × 60 lb bags, 45 × 80 lb bags, or 40 × 90 lb bags. Add 10% for waste, so multiply each number by 1.10 for your actual order quantity.
Is Quikrete the same as regular concrete?
Quikrete is a pre-mixed bagged concrete that contains Portland cement, sand, and aggregate — the same basic ingredients as ready-mix concrete. The difference is that bagged products are batched in a factory and dried; you add water on site. Quikrete 5000 achieves 5,000 PSI — actually stronger than most standard ready-mix residential orders (3,000–3,500 PSI). The trade-off is cost and mixing labor at scale.
How many bags of concrete for a 12×12 slab?
A 12×12 slab at 4 inches thick = 48 ft³ net. With 10% waste = 52.8 ft³. Using 80 lb bags (0.60 ft³ each): 88 bags. Using 60 lb bags (0.45 ft³ each): 118 bags. At 1.95 yd³ total, this is a borderline case — request a short-load ready-mix quote to compare. If the short-load fee pushes ready-mix above $900, bags may still win.
How much water do I add to a bag of concrete?
An 80 lb bag of Quikrete typically requires about 3 quarts (0.75 gallons) of clean water. Add water slowly while mixing — don't dump it all at once. The goal is a stiff, workable mix that holds its shape when squeezed but isn't dry or crumbly. Over-watering is the most common DIY mistake and can reduce final strength by 20–30%.
How long does bagged concrete take to dry?
Bagged concrete reaches initial set in 2–4 hours and is typically walkable after 24 hours. It reaches about 70% design strength at 7 days and full design strength (100%) at 28 days. In cold weather (below 50°F), curing slows significantly — use insulated curing blankets and never pour below 40°F without cold-weather additives. Keep newly poured concrete moist for at least 3–7 days to prevent surface cracking.
Should I use 60 lb or 80 lb bags of concrete?
For most DIY projects, 80 lb bags offer better value — roughly $10–$12 per bag at ~$0.017/cubic inch vs. $8–$9 for 60 lb bags at ~$0.020/cubic inch. However, 80 lb bags are harder to lift and maneuver, especially in a mixer. If you're working alone or have mobility limitations, 60 lb bags are more manageable. For projects over 1 yd³, consider ready-mix regardless of bag size to save mixing labor.