Concrete Calculator

Calculate concrete volume in cubic yards, estimate bags needed, get cost & weight — for slabs, footings, columns & stairs

Concrete Volume Calculator

Select a shape and enter dimensions to calculate how much concrete you need in cubic yards.

Length & Width in ft (or m) — Thickness in inches (or cm)

Length & Width in ft (or m) — Depth in inches (or cm)

Diameter in inches (or cm) — Height in feet (or m)

VOLUME RESULTS

TIP: Always order 5–10% extra concrete to account for spillage, over-excavation, and slight variations in slab thickness.

Concrete Bag Calculator

Enter the volume of concrete needed and select bag size to determine how many bags you need.

BAG ESTIMATE

NOTE: Bag yields are approximate. Actual coverage may vary depending on mix consistency. Add 10% for waste.

Concrete Cost Calculator

Estimate the total cost of your concrete project including material and optional delivery.

COST ESTIMATE

NOTE: Prices vary significantly by region. Ready-mix concrete typically ranges from $125 to $165+ per cubic yard. Contact local suppliers for accurate pricing.

Concrete Weight Calculator

Calculate the weight of your concrete based on volume and mix type.

WEIGHT RESULTS

Concrete Reference Tables

Bag Size Yield (ft³) Yield (yd³) Bags per yd³
40 lb 0.30 0.011 ~90
50 lb 0.375 0.014 ~72
60 lb 0.45 0.017 ~60
80 lb 0.60 0.022 ~45
Slab Thickness Sq Ft per yd³ yd³ per 100 sq ft
2″ 162 0.62
3″ 108 0.93
4″ 81 1.23
5″ 64.8 1.54
6″ 54 1.85
8″ 40.5 2.47
12″ 27 3.70
Concrete Type Weight (lbs/yd³) Weight (kg/m³) Typical Use
Lightweight 3,000 1,780 Insulating fills, roof decks
Standard 4,050 2,400 Slabs, footings, walls
High-Strength 4,800 2,850 Columns, structural elements

How to Calculate Concrete — The Complete Guide

Knowing how to calculate concrete is essential for any construction project. Whether you're pouring a driveway slab, setting fence post footings, or building a foundation, accurately estimating the amount of concrete you need saves time, money, and prevents costly over- or under-ordering.

How to Calculate Cubic Yards of Concrete

To calculate yards of concrete, measure the length, width, and thickness of your project area. Convert all measurements to the same unit (feet), then multiply: Length × Width × Thickness = Cubic Feet. Divide by 27 to get cubic yards. Our concrete volume calculator does this automatically for slabs, footings, columns, and stairs.

How Many Bags of Concrete Do I Need?

The number of concrete bags depends on the total volume and bag size. A standard 80 lb bag covers about 0.6 cubic feet (0.022 yd³). For one cubic yard, you'll need approximately 45 bags of 80 lb mix or 72 bags of 50 lb mix. Use our concrete bag calculator for precise estimates.

Concrete Cost Estimation

Ready-mix concrete costs between $125–$165 per cubic yard for standard mixes. Our concrete cost calculator factors in material cost, delivery fees, short-load charges, and tax to give you a complete concrete slab cost or concrete pad cost estimate.

Concrete Weight Per Cubic Yard

Standard concrete weighs about 4,050 lbs per cubic yard (150 lbs/ft³). Lightweight mixes weigh around 3,000 lbs/yd³, while high-strength concrete reaches 4,800 lbs/yd³. Our concrete weight calculator converts between lbs, kg, and tons.

Frequently Asked Questions

How do I calculate yards of concrete for a slab?+
Measure the slab's length and width in feet, and thickness in inches. Convert thickness to feet by dividing by 12. Multiply length × width × thickness (in feet) to get cubic feet, then divide by 27 for cubic yards. For example: 20ft × 10ft × (4in ÷ 12) = 66.7 ft³ ÷ 27 = 2.47 cubic yards.
How much concrete do I need for a footing?+
Measure the footing length, width, and depth. For a continuous footing 30ft long, 2ft wide, and 12in deep: 30 × 2 × 1 = 60 ft³ ÷ 27 = 2.22 cubic yards. Our concrete footing calculator handles this instantly.
How much does a yard of concrete cost?+
Ready-mix concrete typically costs $125–$165 per yard for standard mixes. Specialty mixes (fiber-reinforced, stamped, colored) cost $150–$200+. Delivery usually adds $50–$100. Short-load fees may apply for orders under 8–10 yards.
How many 80 lb bags of concrete make a yard?+
Approximately 45 bags of 80 lb concrete mix equal one cubic yard. Each 80 lb bag yields about 0.6 cubic feet (0.022 cubic yards).
What is the difference between concrete and cement?+
Cement is an ingredient in concrete. Concrete is a mixture of cement (10–15%), water (15–20%), and aggregates like sand and gravel (60–75%). Pre-mixed bags contain all ingredients — just add water.
How much concrete do I need for a round column?+
Use the formula: Volume = π × (radius²) × height. For a 12-inch diameter column, 8 feet tall: π × (0.5²) × 8 = 6.28 ft³ ÷ 27 = 0.23 yd³. Use our column calculator for multiple columns.