All bag counts are rounded up to the nearest whole bag.
1 cubic yard = 27 cubic feet.
Planning a concrete patio, driveway, or slab project starts with knowing exactly how much material you’ll need. This concrete slab calculator helps you calculate the precise cubic yards and bag counts required so you can accurately estimate your concrete slab price before heading to the supplier or scheduling a ready-mix delivery.
Pro Tip: Most concrete slabs require a compacted stone base for drainage. If you are preparing the sub-base, use our Gravel Driveway Calculatorto estimate the tons of crushed stone required.
Whether you’re budgeting for a DIY backyard patio or a contractor-grade foundation, understanding your material requirements is the first step to controlling costs. Use this concrete price calculator to eliminate guesswork and avoid the expensive mistake of over-ordering or running short mid-project.
How to Use This Concrete Slab Calculator in 3 Simple Steps:
Enter Length & Width — Measure your project area in feet. For irregular shapes, break the area into rectangles and calculate each section separately.
thickness, while driveways typically require 6 inches. Foundations and heavy-duty slabs may need 8 inches or more.
total cubic yards, cubic feet, and the estimated number of premix bags (both 80lb and 60lb options). Use these numbers to estimate concrete cost by multiplying the cubic yards by your local price per yard, or the bag count by your store’s per-bag pricing.
How to Calculate Concrete Price Per Yard
Concrete is almost always sold by the cubic yard when ordering from a ready-mix supplier. To determine your total project cost, you first need to calculate the volume, then multiply by the local concrete price per yard.
Once you have your cubic yards, call local suppliers for their ready-mix cost. Prices vary by region, aggregate type, and delivery distance, but typically range from $120 to $160 per yard.
Real-World Pricing Example:
If you need 1.5 cubic yards and the local rate is $125 per yard, your estimated concrete slab price is $187.50 (before delivery fees or short load charges).
Additional Cost Factors to Consider:
Short Load Fee — Many suppliers charge extra for orders under 10 yards (typically $15–$50).
Delivery Distance — Fees increase for locations beyond the standard radius.
Saturday Deliveries — Expect premium pricing for weekend pours.
Fiber or Color Additives — These enhance durability and aesthetics but add $5–$15 per yard.
Always request a full quote that includes all fees before scheduling delivery. The cost per yard can vary significantly between suppliers in the same area.
💰 Budgeting for your pour? Get a full professional cost breakdown, including labor and regional pricing.
Square Footage Calculator →The essential starting point for any project. Measure any wall or floor area with total accuracy.
Concrete Slab Calculator →Planning a patio or driveway? Estimate the cubic yards and bag counts needed for a solid foundation.
Paint Cost Estimator →Calculate exactly how many gallons you need for your walls based on room size and number of coats.
Precision Tile Calculator →Estimate tile counts and the 10% wastage buffer for kitchen and bathroom renovations.
Brick & Mortar Calculator →Building a garden wall or fire pit? Find the exact number of bricks and mortar bags required.
Mulch Calculator →Refresh your landscape with precision. Calculate bulk yards or bags needed for your garden beds.
Buying Bags? 80lb vs 60lb Concrete Mix
For smaller projects under 2 cubic yards, purchasing premixed bags from Home Depot, Lowe’s, or local hardware stores is often more economical than ordering a ready-mix truck. Bags also give you flexibility to pour in stages without the time pressure of a full truck delivery.
The “Magic Numbers” for Bag Estimates:
80lb Bags (Quikrete/Sakrete): You need approximately 45 bags to make 1 cubic yard of concrete.
60lb Bags: You need approximately 60 bags to make 1 cubic yard of concrete.
Pricing Considerations:
Premix bag prices fluctuate based on location and season, but generally cost between $4 to $6 per bag for standard 80lb mix. During peak construction season (spring/summer), expect prices toward the higher end.
Cost Comparison Example:
1 cubic yard via bags: 45 bags × $5 = $225
1 cubic yard via ready-mix: $125 + $50 short load fee = $175
For volumes over 2 yards, ready-mix becomes significantly cheaper despite delivery fees.
Pro Tips for Bag Projects:
Use the 10% Waste Buffer Toggle — Our calculator includes an optional waste factor. Always enable this for bagged concrete projects, as it’s difficult to achieve perfect yield ratios when hand-mixing. Spillage, uneven mixing, and measurement variations can reduce actual coverage by 5-15%.
Buy Extra Bags — Running out of concrete mid-pour is a disaster. Purchase 2-3 extra bags beyond your calculated amount. Unopened bags can usually be returned, but a partially cured slab cannot be fixed.
Check Expiration Dates — Bags left in storage absorb moisture and harden. Inspect bags at the store; they should feel soft and shift freely when squeezed.
Consider Delivery — Many big-box stores offer free delivery for orders over a certain amount. Having 50+ bags delivered to your driveway saves significant time and vehicle wear.
Frequently Asked Questions
Concrete prices vary by location, supplier, and aggregate specifications. On average, ready-mix concrete costs between $120 and $160 per cubic yard for standard residential-grade mix. If purchasing premixed bags, 1 cubic yard costs approximately $225 to $270 (based on 45 bags at $5–$6 each). Delivery fees, short load charges, and weekend premiums can add $50–$100 to your total cost.
The standard thickness for a residential concrete patio is 4 inches. This provides adequate strength for foot traffic, outdoor furniture, and typical backyard use. If the patio will support heavy planters, outdoor kitchens, or frequent vehicle traffic, increase thickness to 6 inches. Always pour over a compacted gravel base for proper drainage and crack prevention. You can calculate exactly how much gravel you need for the base using our Gravel Driveway Calculator.
For a 10×10 foot slab at the standard 4-inch thickness, you need approximately 1.23 cubic yards of concrete. Using 80lb bags, this equals roughly 56 bags. Using 60lb bags, you’ll need approximately 74 bags. We recommend adding 10% extra (6 more 80lb bags) to account for spillage and leveling adjustments. This calculation assumes a perfectly level subgrade; if your excavation is uneven, additional material will be required.
Yes, but proper planning is critical. When pouring a large slab in multiple sessions, you must create cold joints with rebar or dowels extending into the next section. Without proper reinforcement, the seam will become a weak point prone to cracking. For DIY projects, it’s often better to rent a small mixer and pour the entire slab in one session, or hire a pump truck to place ready-mix concrete quickly.
For slabs 4 inches thick or less, wire mesh (WWF 6×6) is typically sufficient for residential applications like patios and sidewalks. For thicker slabs, driveways, or areas with heavy loads, use #4 rebar spaced 18 inches on center in both directions. Rebar should be positioned in the lower third of the slab (about 1.5 inches from the bottom) using rebar chairs. This reinforcement prevents cracking as the concrete cures and ages.
Approximately 45 bags of 80lb concrete mix equal one cubic yard. Each 80lb bag yields about 0.6 cubic feet when mixed, so 45 bags × 0.6 = 27 cubic feet = 1 cubic yard. For 60lb bags, you need approximately 60 bags per cubic yard since each bag yields about 0.45 cubic feet. Always buy 2-3 extra bags to account for spillage, uneven subgrade, and mixing variations. Most hardware stores accept returns on unopened bags.
For projects under 1 cubic yard (about 45 bags or less), bagged concrete from home improvement stores is usually more economical and convenient. Projects over 2 cubic yards become significantly cheaper with ready-mix delivery despite the delivery fee and minimum order requirements. The break-even point is typically around 1.5 cubic yards. Ready-mix also saves considerable time and labor—mixing 90+ bags by hand is exhausting. Consider ready-mix for any project over 100 square feet at 4 inches thick, or when you need consistent quality throughout a large pour.
Ready-mix concrete costs between $120 and $160 per cubic yard for standard 3000 PSI residential mix. Specialty mixes cost more: 4000 PSI high-strength concrete runs $140-$180 per yard, while fiber-reinforced or colored concrete adds $10-$25 per yard. Bagged concrete costs approximately $225-$270 per cubic yard when you factor in 45 bags at $5-$6 each. Additional costs include delivery fees ($50-$150), short load charges for orders under 10 yards ($50-$100), and Saturday delivery premiums (20-30% extra).
Yes, a compacted gravel base is essential for proper concrete performance. The standard approach is 4 inches of compacted crushed stone (3/4″ clean or crusher run) beneath your concrete slab. This base layer provides drainage to prevent water from pooling under the slab, prevents frost heaving in cold climates, and creates a stable platform that won’t settle unevenly. Without a proper base, concrete is prone to cracking, settling, and moisture problems. You can use our Gravel Calculator to determine exactly how much base material you need.
Yes, pouring a small concrete slab (under 100 square feet) is a manageable DIY project for homeowners with basic construction skills and physical capability. You’ll need proper planning, the right tools, and ideally 2-3 helpers since concrete work is time-sensitive once mixed. Projects larger than 200 square feet or requiring special finishes are better left to professionals who have power equipment and experience achieving level, smooth results. The most critical factors for DIY success are proper site preparation (level, compacted base), accurate calculations to avoid running short, and working quickly before concrete begins to set (typically 60-90 minutes in warm weather).
Essential tools for a DIY concrete slab include: a wheelbarrow or concrete mixer (rent for $50-$75/day), square-point shovel, garden hoe for mixing, screed board (straight 2×4 longer than slab width), bull float or darby for smoothing, hand trowel for edges and finishing, edging tool for rounded corners, grooving tool for control joints, stiff-bristle broom for non-slip texture, rubber boots, and work gloves. For site prep, you’ll need a tamper or plate compactor ($60-$100/day rental) to compact the gravel base. Optional but helpful: knee pads, concrete vibrator for thick pours, and a garden sprayer for curing compound. Total tool rental and purchase costs typically run $150-$300 for a first-time DIY project.
Concrete reaches different strength levels at different times. You can walk on the surface after 24-48 hours once it’s hard enough not to leave footprints. Light use like patio furniture can be placed after 7 days when concrete reaches about 70% of its design strength. However, full curing takes 28 days, at which point concrete reaches its specified strength rating (typically 3000-4000 PSI for residential work). During the first week, keep the concrete moist by lightly spraying with water 2-3 times daily or covering with plastic sheeting to prevent rapid drying and cracking. Avoid heavy loads, vehicle traffic, or high-impact activities for at least 7 days, and ideally wait the full 28 days before subjecting the slab to maximum stress.
You can typically walk on freshly poured concrete after 24 to 48 hours, once the surface is firm and won’t leave footprints or surface marks. In hot weather (above 85°F), concrete may be ready for foot traffic in as little as 18-24 hours. In cold weather (below 50°F), wait a full 48-72 hours. For vehicle traffic, wait at least 7 days to avoid surface damage and tire marks. Heavy vehicles, equipment, or high-impact activities should wait the full 28-day curing period. Temperature, humidity, and concrete mix design all affect curing time—when in doubt, wait longer. It’s better to be patient than to damage a new slab with premature use.
Final Tips for Accurate Estimates
Measure Twice, Pour Once — Verify all dimensions before ordering. Concrete trucks charge by the yard, and sending back excess is expensive.
Account for Waste — Use the 10% buffer toggle in the calculator above. Uneven excavation, spillage, and over-excavation are common on job sites.
Check Local Codes — Some municipalities require permits and inspections for slabs over a certain size. Verify requirements before starting.
Plan for Weather — Concrete cures best between 50°F and 85°F. Avoid pouring in extreme heat, freezing conditions, or when rain is forecasted within 24 hours.
Ready to calculate? Use the tool above to get your exact cubic yards and bag counts, then contact local suppliers for current pricing. With accurate volume calculations and smart material sourcing, you can complete your concrete project on budget and on schedule.
Trusted by DIYers and contractors nationwide — always verify calculations with your supplier before ordering.
