Concrete Bag Calculator — 40lb · 60lb · 80lb · Quikrete · Sakrete
80lb Bag of Concrete Cubic Feet — All Bag Sizes, All Project Types
40 lb bag = 0.30 ft³ → 3.33 bags per ft³
50 lb bag = 0.375 ft³ → 2.67 bags per ft³
60 lb bag = 0.45 ft³ → 2.22 bags per ft³
80 lb bag = 0.60 ft³ → 1.67 bags per ft³
1 cubic yard = 27 ft³
80lb bags per cubic yard: 45 bags
An 80lb bag of concrete mix yields 0.60 cubic feet of mixed concrete. A 60lb bag yields 0.45 cubic feet, and a 40lb bag yields 0.30 cubic feet. Use our free concrete bag calculator to find exactly how many bags you need for any project — slabs, footings, fence posts, steps and more. Enter your project dimensions and select your bag size to get an instant bag count with cost estimate. Covers all Quikrete, Sakrete and generic concrete mix bag sizes.
Enter project dimensions, choose a bag size, and get exact bag count, volume, and cost instantly.
Unit: ft
Unit: ft
Unit: in
80lb bags are the most common and usually the best value per cubic foot.
Unit: %
Every bag size, every conversion you need
| Bag Size | ft³/bag | Bags/ft³ | Bags/yd³ | ft³/bag exact | Avg Cost |
|---|---|---|---|---|---|
| 40 lb | 0.30 ft³ | 3.33 | 90 bags | 0.300 | ~$4.48 |
| 50 lb | 0.375 ft³ | 2.67 | 72 bags | 0.375 | ~$5.48 |
| 60 lb | 0.45 ft³ | 2.22 | 60 bags | 0.450 | ~$5.98 |
| 80 lb ⭐ | 0.60 ft³ | 1.67 | 45 bags | 0.600 | ~$6.98 |
Volume: 33.3 ft³ (1.23 yd³)
80lb bags: 62 bags (with 10% waste)
60lb bags: 82 bags
Volume: 66.7 ft³ (2.47 yd³)
80lb bags: 123 bags
→ Consider ready-mix concrete!
10" hole × 24" deep
Volume: 10.9 ft³
80lb bags: 21 bags (≈ 2 per post)
20 ft long
Volume: 20.0 ft³
80lb bags: 37 bags
Volume: ~8.5 ft³
80lb bags: 16 bags
Add 15% waste for complex forms
Volume: 133.3 ft³ (4.94 yd³)
80lb bags: 246 bags
→ STRONGLY recommend ready-mix!
• 40lb bag = 0.30 ft³ = 90 bags/yd³
• 60lb bag = 0.45 ft³ = 60 bags/yd³
• 80lb bag = 0.60 ft³ = 45 bags/yd³
• 1 yd³ = 27 ft³
• 1 ft³ = 1.67 × 80lb bags
Formula: Bags = (L × W × T/12) × 1.10 ÷ ft³/bag
• 2 in: Walkways, thin overlays
• 3 in: Light foot traffic paths
• 4 in: Standard residential slab ⭐
• 6 in: Driveways, heavy loads
• 8 in: Structural/commercial slabs
10×10 slab @ 4\": 62 × 80lb bags. @ 6\": 92 × 80lb bags.
Use bagged for projects under 1 yd³, DIY repairs, and sites with poor truck access.
Use ready-mix for projects at or above 1 yd³, larger slabs, and time-sensitive pours.
Ready-mix: about $150–$200/yd³. 80lb bags: about $315/yd³.
Pre-calculated bag counts for all common project sizes
| Slab Size | Area ft² | Volume ft³ | Volume yd³ | 80lb Bags | 60lb Bags | 40lb Bags |
|---|---|---|---|---|---|---|
| 4 × 4 ft | 16 ft² | 5.3 ft³ | 0.20 yd³ | 10 bags | 14 bags | 20 bags |
| 4 × 8 ft | 32 ft² | 10.7 ft³ | 0.40 yd³ | 20 bags | 27 bags | 40 bags |
| 10 × 10 ft | 100 ft² | 33.3 ft³ | 1.23 yd³ | 62 bags | 82 bags | 123 bags |
| 10 × 20 ft | 200 ft² | 66.7 ft³ | 2.47 yd³ | 123 bags | 163 bags | 245 bags |
| 12 × 12 ft | 144 ft² | 48.0 ft³ | 1.78 yd³ | 89 bags | 118 bags | 177 bags |
| 12 × 20 ft | 240 ft² | 80.0 ft³ | 2.96 yd³ | 148 bags | 197 bags | 296 bags |
| 20 × 20 ft | 400 ft² | 133.3 ft³ | 4.94 yd³ | 246 bags | 328 bags | 493 bags |
| 20 × 30 ft | 600 ft² | 200.0 ft³ | 7.41 yd³ | 370 bags | 493 bags | 740 bags |
| Slab Size | Area ft² | Volume ft³ | Volume yd³ | 80lb Bags | 60lb Bags |
|---|---|---|---|---|---|
| 10 × 10 ft | 100 ft² | 50.0 ft³ | 1.85 yd³ | 92 bags | 123 bags |
| 10 × 20 ft | 200 ft² | 100.0 ft³ | 3.70 yd³ | 184 bags | 245 bags |
| 12 × 12 ft | 144 ft² | 72.0 ft³ | 2.67 yd³ | 133 bags | 177 bags |
| 20 × 20 ft | 400 ft² | 200.0 ft³ | 7.41 yd³ | 370 bags | 493 bags |
| Post Hole | Depth | 1 Post | 5 Posts | 10 Posts | 20 Posts |
|---|---|---|---|---|---|
| 8" diameter | 24" deep | 0.58 ft³ / 1 bag | 6 bags | 11 bags | 22 bags |
| 10" diameter | 24" deep | 0.91 ft³ / 2 bags | 9 bags | 17 bags | 34 bags |
| 10" diameter | 36" deep | 1.36 ft³ / 3 bags | 13 bags | 26 bags | 51 bags |
| 12" diameter | 24" deep | 1.31 ft³ / 3 bags | 13 bags | 25 bags | 49 bags |
| 12" diameter | 36" deep | 1.96 ft³ / 4 bags | 19 bags | 37 bags | 73 bags |
| Footing Size | Length | Volume ft³ | Volume yd³ | 80lb Bags |
|---|---|---|---|---|
| 12"W × 12"D | 10 ft | 10.0 ft³ | 0.37 yd³ | 19 bags |
| 12"W × 12"D | 20 ft | 20.0 ft³ | 0.74 yd³ | 37 bags |
| 16"W × 12"D | 20 ft | 26.7 ft³ | 0.99 yd³ | 49 bags |
| 24"W × 12"D | 20 ft | 40.0 ft³ | 1.48 yd³ | 74 bags |
| 24"W × 18"D | 20 ft | 60.0 ft³ | 2.22 yd³ | 110 bags |
The right concrete mix and thickness for every project type
Walkways 3–4 inches, patios 4 inches, driveways 6 inches, heavy slabs 8+ inches. A 12×12 patio at 4 inches is 48 ft³ and needs about 89 bags of 80lb concrete with 10% waste. Use standard Quikrete Concrete Mix or Quikrete 5000 for higher strength.
Deck footings often start at 12"W × 12"D. A 20 ft footing at 12" × 12" is 20 ft³ and needs about 37 x 80lb bags with waste. Use Quikrete 5000 or Sakrete 5000 Plus for structural work and always check frost depth.
A 4×4 post usually uses a 10–12 inch hole at 24–36 inches deep. 8" × 24" uses about 1 bag, 10" × 24" about 2 bags, 12" × 36" about 4 bags. Quikrete Fast-Setting Concrete is the easiest choice for posts.
Standard residential steps are about 7 inches rise and 11 inches run. A 3-step, 48-inch-wide staircase needs roughly 8.5 ft³, or about 17 x 80lb bags with 15% waste. Quikrete 5000 works well for steps and takes a broom finish for traction.
Mailbox posts, deck posts, basketball hoops, and flagpoles all use the same cylinder-hole logic. A 12" × 36" basketball hoop hole is about 2.36 ft³ raw and roughly 5 x 80lb bags with waste.
For projects under about 1 ft³, 40lb bags often make more sense because you reduce waste. Use patchers, self-leveling underlayment, or hydraulic cement where standard concrete mix is not the right product.
Quikrete and Sakrete product guide by project type
Quikrete Concrete Mix and Sakrete standard mix come in 40lb, 60lb, and 80lb bags. An 80lb bag yields 0.60 ft³ and usually reaches about 4,000 psi. Best for general slabs, posts, steps, and most DIY concrete jobs.
Quikrete 5000 and Sakrete 5000 Plus are better for colder weather, structural footings, and projects that need faster return to use. An 80lb bag still yields about 0.60 ft³ but with higher early strength and about 5,000 psi at 28 days.
Quikrete Fast-Setting and Sakrete Fast-Set are ideal for fence posts and anchor applications. A 50lb bag yields about 0.375 ft³ and can be poured dry into a post hole before adding water. Set time is often 20–40 minutes.
Fiber-reinforced mixes help outdoor slabs resist cracking. They are especially useful for driveways, patios in freeze-thaw climates, and slabs with higher movement risk. Yield stays close to standard mixes for the same bag size.
Self-leveling concrete is for interior floor prep, not general slab work. A 50lb bag often covers around 40 ft² at 1/8 inch. It is much more expensive per ft³ and should only be used when leveling is the goal.
Hydraulic cement is a specialized repair product for active water leaks, wet cracks, and pipe penetrations. It sets in minutes and is not a substitute for general concrete mix when pouring slabs or posts.
Six detailed calculations for common DIY concrete projects
A 10×10 slab at 4 inches thick is 33.3 ft³ raw. Add 10% waste to reach 36.7 ft³. That needs 62 x 80lb bags or 82 x 60lb bags. At 1.36 yd³ with waste, ready-mix may save money if a truck can reach the site.
Ten post holes at 10 inches diameter and 30 inches deep total about 13.6 ft³ raw. With 10% waste that becomes 15.0 ft³, or about 25 x 80lb bags. Fast-setting 50lb concrete is often preferred for easier post installation.
An 8×4 section at 6 inches thick is 16.0 ft³ raw and 17.6 ft³ with waste. That works out to about 30 x 80lb bags. High-early-strength concrete is a smart choice if you need faster traffic return.
Six deck footings at 12 inches diameter and 42 inches deep total about 16.5 ft³ raw. Add 10% waste and plan on 31 x 80lb bags. Structural footings should extend below frost depth and follow local code.
A 3-step set 48 inches wide with 7 inch rise and 11 inch run needs about 8.5 ft³ raw. With 15% waste, plan for about 17 x 80lb bags. Quikrete 5000 is a strong choice for steps and stairs.
A 12 inch diameter, 36 inch deep hoop base is about 2.36 ft³ raw and 2.60 ft³ with waste. That means about 5 x 80lb bags or 7 x 50lb fast-setting bags, depending on how quickly you want it set.
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Common questions about concrete bag cubic feet.
An 80lb bag of concrete mix yields: 0.60 cubic feet of mixed concrete This means: 1 ft³ requires 1.67 × 80lb bags 1 yd³ (27 ft³) requires 45 × 80lb bags The 80lb bag is the most popular size for DIY projects because it offers the best balance of yield and manageability. Quikrete 80lb and Sakrete 80lb bags both commonly list 0.60 ft³ yield.
A 60lb bag of concrete mix yields: 0.45 cubic feet of mixed concrete This means: 1 ft³ requires 2.22 × 60lb bags 1 yd³ (27 ft³) requires 60 × 60lb bags Choose 60lb bags when you need easier lifting, but note that 80lb bags are usually cheaper per cubic foot.
A 40lb bag of concrete mix yields: 0.30 cubic feet of mixed concrete This means: 1 ft³ requires 3.33 × 40lb bags 1 yd³ (27 ft³) requires 90 × 40lb bags 40lb bags are best for small repairs, patches, and projects under about 2 ft³.
You need 45 bags of 80lb concrete mix to make one cubic yard of concrete. Calculation: 1 cubic yard = 27 cubic feet 1 × 80lb bag = 0.60 ft³ 27 ÷ 0.60 = 45 bags That also makes the 80lb bag the cheapest bagged option per cubic yard in most stores.
For a 10×10 ft slab at 4 inches thick: Step 1: Calculate volume ft³ = 10 × 10 × (4 ÷ 12) = 33.3 ft³ Step 2: Add 10% waste 33.3 × 1.10 = 36.7 ft³ Step 3: Divide by ft³ per bag 80lb bags: 36.7 ÷ 0.60 = 61.2 → 62 bags 60lb bags: 36.7 ÷ 0.45 = 81.6 → 82 bags 40lb bags: 36.7 ÷ 0.30 = 122.3 → 123 bags At 1.36 yd³ with waste, compare ready-mix pricing too.
For fence posts, bag count depends on hole diameter and depth. Typical 80lb bag counts per post: 8" diameter × 24" deep: ~1 bag 10" diameter × 24" deep: ~2 bags 10" diameter × 30" deep: ~2–3 bags 12" diameter × 24" deep: ~3 bags 12" diameter × 36" deep: ~4 bags Fast-setting concrete is ideal for posts because you can pour dry mix into the hole and add water on top.
Use bagged concrete when the project is under about 1 cubic yard, truck access is poor, or you need flexibility. Use ready-mix when the project is 1 cubic yard or more, time is critical, or you want to reduce labor. Bagged 80lb concrete is often about $315 per cubic yard, while ready-mix is often about $150–$200 per cubic yard delivered. For larger pours, ready-mix usually wins on both cost and labor.
From cubic meters to cubic feet, compare volumes quickly with clear formulas and fast results.