Concrete Bag Calculator
Shopping list for bagged mix (Quikrete, Sakrete and similar). Enter the pour size, pick a bag weight, and optionally override the yield with the ft³ printed on your bag label. Returns whole bags to buy — not a ready-mix order.
Enter your measurements to see what to buy.
How to calculate it
Shopping list for bagged mix (Quikrete, Sakrete and similar). Enter the pour size, pick a bag weight, and optionally override the yield with the ft³ printed on your bag label. Returns whole bags to buy — not a ready-mix order.
Source: Bag yields follow manufacturer-published values: 40 lb ≈ 0.30 ft³, 60 lb ≈ 0.45 ft³, 80 lb ≈ 0.60 ft³ (typical for Quikrete/Sakrete premixed concrete).
A 3×3 ft footing pad at 4 in thick = 3 ft³. Using 80 lb bags (0.60 ft³ each): 3 ÷ 0.60 = 5 bags before waste, 6 bags with 10% waste.
Want the full step-by-step walkthrough? Read our How to Plan and Pour a Concrete Patio Slab.
Bag yield reference
Bag count comes down to one formula: total volume ÷ bag yield. Use this table to pick the right bag size and estimate how many bags equal a cubic yard of ready-mix.
| Bag size | Yield per bag | Bags per cubic yard | Best for |
|---|---|---|---|
| 40 lb | 0.30 ft³ | ~90 bags | Small repairs, post holes |
| 50 lb | 0.375 ft³ | ~72 bags | Fast-setting post mix |
| 60 lb | 0.45 ft³ | ~60 bags | Medium pours, easier lifting |
| 80 lb | 0.60 ft³ | ~45 bags | Larger pours, fewest bags |
Yields follow typical manufacturer-published values. Past about 45 eighty-pound bags (1 cubic yard), delivered ready-mix is usually cheaper and far less labor.
How to use this calculator
- Enter the length and width of your pour and the depth in inches.
- Pick your bag size — 40, 50, 60 or 80 lb — to match what the store sells.
- The calculator returns the exact bag count to buy, rounded up with your waste allowance.
- Enter the price per bag for an optional total material cost.
Purchasing & waste guidance
- 40 lb bag ≈ 0.30 ft³ (about 90 bags per cubic yard).
- 60 lb bag ≈ 0.45 ft³ (about 60 bags per cubic yard).
- 80 lb bag ≈ 0.60 ft³ (about 45 bags per cubic yard).
- Past roughly 1 cubic yard (about 45 eighty-pound bags), delivered ready-mix is usually cheaper and far less work.
Waste factor guidance
- 10% covers spillage and uneven holes for typical bagged pours.
- Use 15% for post holes in loose or rocky soil where voids are common.
- For a single small pad on flat ground, 5% is usually sufficient.
Common mistakes to avoid
- Mixing bag sizes in one estimate — yields differ, so total the count for one bag size, not a blend.
- Forgetting that 80 lb bags are heavy; 60 lb bags are easier to handle but you need more of them.
- Buying exactly the calculated count with no spare — keep an extra bag for touch-ups.
Assumptions & what’s included
- Bag yields use manufacturer-published averages (40 lb ≈ 0.30, 50 lb ≈ 0.375, 60 lb ≈ 0.45, 80 lb ≈ 0.60 ft³).
- Waste allowance covers spillage and uneven holes.
- Price is per bag and optional.
Sources & references
- Bag yields (40 lb ≈ 0.30, 50 lb ≈ 0.375, 60 lb ≈ 0.45, 80 lb ≈ 0.60 ft³) follow published product data from Quikrete and Sakrete premixed concrete technical data sheets.
- Bags-per-cubic-yard conversions derive from 27 ft³ per cubic yard ÷ bag yield.
- Yields vary slightly by product and moisture — always confirm the exact yield on the bag label before ordering.
Learn more about how every calculator works on our methodology page.
Frequently asked questions
How many 80 lb bags of concrete make a cubic yard?
About 45 eighty-pound bags make 1 cubic yard (27 ft³ ÷ 0.60 ft³ per bag). For a 60 lb bag it’s about 60 bags, and for a 40 lb bag about 90 bags.
How many bags of concrete do I need for a fence post?
A typical 4×4 post in an 8 in wide × 24 in deep hole needs about 0.7 ft³, or two 80 lb bags per post. Add a third bag for 6 ft fences or loose soil.
What is the yield of a bag of concrete?
Manufacturers publish yields of roughly 0.30 ft³ for 40 lb, 0.45 ft³ for 60 lb and 0.60 ft³ for 80 lb bags. Always check the bag label — yields vary slightly by product.
Should I buy 60 lb or 80 lb bags?
80 lb bags mean fewer bags to buy and less packaging, but they are heavy to lift and mix. 60 lb bags are easier to handle for a DIY pour but you will need about a third more of them.
How many bags of concrete do I need for a 4×4 pad?
A 4×4 ft pad at 4 in thick is 5.33 ft³. With 80-lb bags and a 10% waste allowance you need about 10 bags. The calculator gives an exact count for any size and bag weight.
How many bags of concrete are in a cubic yard?
About 45 eighty-pound bags, 60 sixty-pound bags, or 90 forty-pound bags make one cubic yard (27 ft³). Past that point, delivered ready-mix is usually cheaper and far less labor.
How long does bagged concrete take to cure?
Bagged concrete is walkable in 24–48 hours and reaches full design strength at about 28 days. Keep it damp and covered for the first week so it cures slowly and avoids surface cracking.
Related guides
Step-by-step project guides that use this calculator.