Understanding how much area a single bag of concrete can cover is essential for planning any pour, whether you are patching a sidewalk, setting fence posts, or pouring a small slab. Our free concrete bag coverage calculator tells you exactly how many bags you need based on your project dimensions and the bag size you plan to purchase.

Simply enter the length, width, and depth of your pour, select your bag size, and our calculator instantly shows you the total volume, number of bags required, and the coverage area per bag.

Standard Bag Weights

Concrete is sold in several standard bag sizes at home improvement stores and building supply yards:

• 40 lb bags: Approximately 0.30 cubic feet per bag
• 50 lb bags: Approximately 0.375 cubic feet per bag
• 60 lb bags: Approximately 0.45 cubic feet per bag
• 80 lb bags: Approximately 0.60 cubic feet per bag
• 90 lb bags: Approximately 0.675 cubic feet per bag

Coverage Area by Bag Size and Depth

40 lb bag coverage:

• 1 inch deep: approximately 3.6 square feet
• 2 inches deep: approximately 1.8 square feet
• 3 inches deep: approximately 1.2 square feet
• 4 inches deep: approximately 0.9 square feet

60 lb bag coverage:

• 1 inch deep: approximately 5.4 square feet
• 2 inches deep: approximately 2.7 square feet
• 3 inches deep: approximately 1.8 square feet
• 4 inches deep: approximately 1.35 square feet

80 lb bag coverage:

• 1 inch deep: approximately 7.2 square feet
• 2 inches deep: approximately 3.6 square feet
• 3 inches deep: approximately 2.4 square feet
• 4 inches deep: approximately 1.8 square feet

The Formula

Step 1: Calculate volume in cubic feet:

Volume = Length (ft) x Width (ft) x Depth (ft)

Step 2: Divide by bag coverage:

Bags needed = Total cubic feet / Cubic feet per bag

Step 3: Round up and add waste:

Final count = Rounded bags x (1 + Waste percentage)

Example Calculations

3x3 foot patch, 3 inches deep, using 80 lb bags:

• Volume: 3 x 3 x 0.25 = 2.25 cubic feet
• Bags: 2.25 / 0.60 = 3.75 = 4 bags
• With 10% waste: 5 bags

4x8 foot sidewalk section, 4 inches deep, using 60 lb bags:

• Volume: 4 x 8 x 0.33 = 10.67 cubic feet
• Bags: 10.67 / 0.45 = 23.7 = 24 bags
• With 10% waste: 27 bags

10x10 foot shed slab, 4 inches deep, using 80 lb bags:

• Volume: 10 x 10 x 0.33 = 33.3 cubic feet
• Bags: 33.3 / 0.60 = 55.5 = 56 bags
• With 10% waste: 62 bags

Standard Concrete Mix

Regular pre-mixed concrete (gray):

• Most common type
• 4000 psi typical strength
• Used for slabs, footings, posts, and general construction
• Available in 40, 60, 80, and 90 lb bags

Fast-Setting Concrete

Quick-set concrete:

• Sets in 20-40 minutes
• Ideal for setting posts and small repairs
• No mixing required for post setting (pour dry, add water)
• 20-40 minute working time
• Available in 50 and 80 lb bags

High-Strength Concrete

5000+ psi mixes:

• For heavy-duty applications
• Higher cement content
• Better for freeze-thaw resistance
• Used for driveways, garage floors, and commercial applications

Specialty Concrete Mixes

• Crack-resistant: Contains fibers for reduced cracking
• Lightweight: Lower density for specific applications
• Counter-top mix: Formulated for thin, smooth surfaces
• Mortar mix: For brick, block, and stone (not structural concrete)
• Sand mix: For thin applications (1/2 to 2 inch depth)

Use Bags When:

• Project volume is under 1 cubic yard (27 cubic feet)
• Access is limited: Wheelbarrow and bag transport easier than truck
• Working alone: Mix and pour at your own pace
• Remote locations: Delivery trucks cannot reach
• Multiple small pours: Spread work over several days
• Small repairs and patches: Quick and convenient

Order Ready-Mix When:

• Project volume is over 1 cubic yard
• Need consistent quality across the entire pour
• Large slab must be poured at once (avoid cold joints)
• Time is critical: Ready-mix is much faster for large jobs
• Specific mix design required: Custom strengths and admixtures

Cost Comparison

Bagged concrete (80 lb, approximately $5-7 per bag):

• 1 cubic yard = approximately 45 bags = $225-315
• Does not include mixing labor

Ready-mix delivered:

• 1 cubic yard = approximately $120-180 (plus delivery fee)
• Minimum delivery charge may apply (typically $150-300)
• For 1+ cubic yards, ready-mix is usually more economical

Mixing Ratio

Standard bagged concrete:

• Add 2-3 quarts of water per 80 lb bag
• Start with less water, add gradually
• Mix until uniform consistency
• Avoid too much water (weakens concrete)

Mixing Methods

Wheelbarrow and hoe:

• Good for up to 3-4 bags at a time
• Most common DIY method
• Physical labor required

Electric mixer:

• Handles 2-3 bags per batch
• More consistent mixing
• Available for rental ($50-75 per day)
• Recommended for 10+ bag projects

Direct in hole:

• For fast-setting concrete only
• Pour dry mix in hole, add water
• Only for non-structural post setting

Water Management

Getting the right consistency:

• Too dry: Difficult to work, poor consolidation, weak spots
• Too wet: Easier to place but significantly weaker concrete
• Ideal slump: 4-5 inches (thick but workable)
• Start dry: Always add water gradually to avoid over-wetting

Why Actual Yield May Vary

• Moisture in aggregate: Can slightly affect volume
• Mixing method: Incomplete mixing reduces yield
• Spillage: Always occurs during mixing and pouring
• Subgrade irregularities: Uneven base consumes more concrete
• Over-excavation: Hole may be deeper than planned

Always Order Extra

• Minimum extra: 10% above calculated amount
• Recommended: 15% for DIY projects
• Irregular shapes: 20% extra recommended
• Post holes: 10-15% extra for uneven holes

How many 80 lb bags make a cubic yard?

• Each 80 lb bag yields approximately 0.60 cubic feet
• One cubic yard = 27 cubic feet
• Bags per cubic yard: 27 / 0.60 = 45 bags
• With 10% waste: order 50 bags per cubic yard

How much area does one 80 lb bag of concrete cover?

Coverage depends on depth:

• At 2 inches deep: approximately 3.6 square feet
• At 3 inches deep: approximately 2.4 square feet
• At 4 inches deep: approximately 1.8 square feet
• At 6 inches deep: approximately 1.2 square feet

Should I use 60 lb or 80 lb bags?

Consider these factors:

• 80 lb bags: Better value per cubic foot, fewer bags to handle, each bag is heavier
• 60 lb bags: Easier to carry and handle, better for smaller people or solo workers
• Cost per cubic foot: 80 lb bags are typically 10-15% more economical
• Choose based on your physical ability and project size

How many bags do I need for a 10x10 slab at 4 inches?

• Volume: 33.3 cubic feet (1.23 cubic yards)
• 80 lb bags: 56 bags
• 60 lb bags: 75 bags
• With 10% waste: 62 bags (80 lb) or 83 bags (60 lb)
• Consider ready-mix delivery for this volume

Can I mix different brands of concrete together?

Generally yes, but with caution:

• Different brands may have slightly different set times
• Try to use the same brand for consistent results
• If mixing brands, use same strength rating (e.g., all 4000 psi)
• Color may vary slightly between brands
• For visible surfaces, use one brand for consistency

Understanding concrete bag coverage helps you plan your project efficiently and buy the right amount of material. Use our calculator to estimate your needs, add 10-15% for waste, and you will be ready to pour with confidence.

Remember: It is always better to have one extra bag than to run short in the middle of a pour. Extra bags can be returned to most home improvement stores if unopened.