Concrete Calculator
Enter your project dimensions and get instant estimates for volume, bags, weight, and cost — a free online concrete calculator, quantity calculator and estimator tool in one.
Popular Concrete Calculators
Purpose-built calculators for every kind of concrete project.
How to Use This Calculator
Estimate any concrete pour in three simple steps — no math required.
Choose Your Project
Select the type of concrete project you're working on — slab, footing, wall, column or post hole.
Enter Dimensions
Enter length, width and thickness in your preferred units — feet, inches, meters or centimeters.
Get Instant Results
Instantly see volume, bags required, weight and estimated cost — ready to order or buy.
What Can You Calculate?
One calculator, every concrete project — from a single fence post to a full foundation.
Handy Concrete Tools
Quick converters and guides to help you measure, buy and pour with confidence.
Supported Units
Calculate concrete using your preferred unit of measurement — by feet, by area, by cubic yards or fully metric.
Concrete Mix Ratios & Grades
The right mix and grade depend on what you're building. Mix ratios describe the proportion of cement, sand and aggregate; grades describe the compressive strength the cured concrete reaches at 28 days.
Concrete Mix Ratios
A 1:2:3 mix with a 0.5 water-cement ratio reaches roughly 3,000 psi — plenty for most DIY projects. Richer mixes (more cement) cure stronger but cost more and are more prone to shrinkage cracking.
Concrete Grades (Strength)
The "M" stands for mix; the number is the characteristic strength in MPa at 28 days. M20 (≈2,900 psi) is the workhorse grade for residential slabs, while M30+ suits driveways and load-bearing elements.
Material & Cost Estimator
Estimate every material — ready mix, dry pour, cement bags, sand, gravel, aggregate and ballast — then price it out. Material needs scale directly with volume, so nail the volume first.
Delivered by truck, batched to spec. The best option for pours over one cubic yard.
Bagged mix placed dry and hydrated in place — popular for small non-structural slabs.
The binder. Roughly 6–8 × 50 kg bags of cement per cubic meter of a standard mix.
Fine aggregate fills voids between gravel. About 0.5 m³ of sand per cubic meter of concrete.
Coarse aggregate provides bulk and strength. About 0.75 m³ of gravel per cubic meter.
All-in ballast — pre-mixed sand and gravel, the convenient aggregate for DIY mixes.
What Affects Concrete Cost?
The six inputs behind every concrete price, labor cost and quote — know them before you call for a price per square foot.
Volume drives everything — bigger pours cost more in total but less per cubic yard.
Going from 4 to 6 inches adds 50% more concrete. Thickness is the hidden price lever.
Short-load fees of $50–$150 apply below about 4 cubic yards; distance adds cartage.
Placing and finishing adds $40–$60 per cubic yard — more for decorative finishes.
The 5–10% ordered beyond net volume. Cheap insurance against a short pour.
The base rate — typically $120–$180 per cubic yard, varying with grade and market.
Volume & Weight Reference
The conversions and densities every concrete estimate is built on.
| From | Equals |
|---|---|
| 1 cubic yard (yd³) | 27 cubic feet |
| 1 cubic yard (yd³) | 0.765 cubic meters |
| 1 cubic meter (m³) | 1.308 cubic yards |
| 1 cubic meter (m³) | 1,000 litres |
| 1 cubic foot (ft³) | 28.32 litres |
| 1 cubic foot (ft³) | 0.037 cubic yards |
| Concrete Type | Weight (kg/m³) |
|---|---|
| Normal Concrete | 2,400 |
| Reinforced Concrete | 2,500 |
| Lightweight Concrete | 1,800 |
| High-Strength Concrete | 2,600+ |
| Per cubic yard (normal) | ≈ 1,839 kg / 4,050 lb |
| Per cubic foot (normal) | ≈ 68 kg / 150 lb |
Why Trust Our Calculator?
Calculate concrete by area or volume, estimate by cubic yards or cubic meters, convert between metric and imperial, and estimate bagged concrete — for DIY or professional projects.
Every shape uses its exact geometric formula — no approximations.
Feet, inches, meters, centimeters — convert between metric and imperial instantly.
Calculate material quantities for DIY projects — bags, sand, gravel and cost.
Yardage, mix grades, rebar and load tools that professionals rely on.
A completely free concrete calculator online — no sign-up, no downloads.
The full estimator tool works on any phone, right at the jobsite.
Concrete Learning Center
Everything you need to plan, order and pour concrete with confidence — written for DIYers and useful for pros.
Volume = length × width × thickness. Learn the formula, unit conversions and how to handle odd shapes like circles and trapezoids.
Read guide → Concrete Mix RatiosWhat 1:2:3 and 1:2:4 really mean, how water-cement ratio drives strength, and which mix to choose for slabs vs. footings.
Read guide → Concrete GradesFrom M10 blinding concrete to M35 structural mixes — what each grade is for and how MPa translates to psi.
Read guide → Concrete Thickness Guide4" for patios, 5–6" for driveways, 8" for heavy loads. How to pick thickness — and why the subbase matters as much as the slab.
Read guide → Concrete Cost GuideReady-mix pricing, short-load fees, labor rates and how to budget a pour without surprises.
Read guide → Ready-Mix vs BaggedThe break-even point is around one cubic yard. When to order a truck, when to mix bags — and the true cost of each.
Read guide → Concrete Volume FormulaRectangles, circles, tubes and trenches — the exact formula for each shape with worked examples in both unit systems.
Read guide → Concrete Weight FormulaWeight = volume × density. Why normal concrete weighs 2,400 kg/m³ and how reinforcement and aggregates change it.
Read guide →Frequently Asked Questions
Quick answers to the most common concrete questions.
How much concrete do I need?
Multiply length × width × thickness (all in the same unit) to get volume, then convert to cubic yards or cubic meters. For example, a 10 ft × 10 ft slab at 4 inches thick needs 10 × 10 × 0.333 = 33.3 ft³ ≈ 1.23 cubic yards. Our calculator handles the conversion and adds a waste allowance automatically.
How many bags of concrete do I need?
Divide total volume by the yield of one bag: an 80 lb bag yields ≈ 0.60 ft³, a 60 lb bag ≈ 0.45 ft³, and a 50 lb bag ≈ 0.375 ft³. Always round up and add 5–10% for waste. A full cubic yard needs about 45 × 80 lb bags. Try the concrete bag calculator.
How do I calculate cubic yards of concrete?
Multiply length (ft) × width (ft) × thickness (ft) to get cubic feet, then divide by 27. Example: a 12 × 12 ft pad at 4" thick → 12 × 12 × 0.33 = 47.5 ft³ ÷ 27 ≈ 1.76 yd³. Use the cubic yard calculator for instant yardage.
How thick should a concrete slab be?
Most residential slabs — patios, walkways, shed bases — are 4 inches. Driveways carrying vehicles should be 5–6 inches, and slabs supporting heavy equipment 6–8 inches with rebar reinforcement. Always pour over 3–4" of compacted gravel.
How much does concrete weigh?
Normal-weight concrete weighs about 2,400 kg/m³ (150 lb/ft³, or roughly 4,050 lb per cubic yard). Reinforced concrete is ≈ 2,500 kg/m³ and lightweight mixes around 1,800 kg/m³. See the weight calculator.
How much does concrete cost?
Ready-mix typically runs $120–$180 per cubic yard delivered in the US, plus possible short-load fees for orders under a full truck. Bagged concrete costs $5–$10 per 80 lb bag. Add labor ($40–$60/yd³ finished) and 5–10% waste — or use the cost calculator.
How much extra concrete should I order?
Order 5–10% extra to cover spillage, uneven subgrade and form variations — 10% for complex shapes or rough excavation. Running short mid-pour creates cold joints that weaken the slab.
What's the difference between cement and concrete?
Cement is the binding powder; concrete is the finished material — cement mixed with sand, gravel and water. Cement makes up only 10–15% of a typical concrete mix.
What concrete mix ratio should I use?
A 1:2:3 mix (cement : sand : gravel) suits general construction; 1:2:4 is common for residential slabs and footings. For structural work, use a specified grade like M20–M35 instead of mixing by ratio. See the 1:2:3 mix calculator.
What do concrete grades like M20 mean?
The M stands for "mix" and the number is the compressive strength in MPa at 28 days. M20 reaches 20 MPa (≈ 2,900 psi) — the standard grade for residential slabs and footings. Batch it with the M20 calculator.
How many cubic feet are in a yard of concrete?
One cubic yard = 27 cubic feet (3 × 3 × 3 ft). It also equals about 0.765 cubic meters or 765 litres.
How many 80 lb bags make a yard of concrete?
About 45 bags. Each 80 lb bag yields ≈ 0.60 ft³, and 27 ÷ 0.60 = 45. For 60 lb bags you'd need 60; for 50 lb bags, 72. Details on the 80 lb bag calculator.
Can I pour concrete directly on dirt?
Not recommended. Pour over 3–4 inches of compacted gravel for drainage and a stable base. Concrete on loose soil settles unevenly and cracks.
How long does concrete take to cure?
Concrete sets in 24–48 hours (walkable), reaches ~70% strength at 7 days, and its design strength at 28 days. Keep it moist for the first week for maximum strength. Track it with the PSI calculator.
Is ready-mix or bagged concrete cheaper?
Over about 1 cubic yard, ready-mix delivered by truck is usually cheaper and far less labor. Bags win for small pours, repairs and setting posts. Compare with the material calculator.
How much area does a yard of concrete cover?
At 4" thick, one cubic yard covers ≈ 81 ft²; at 6", ≈ 54 ft². Rule of thumb: coverage (ft²) = 324 ÷ thickness in inches.
Do I need rebar or wire mesh in my slab?
Slabs 4" and thicker benefit from reinforcement. Wire mesh suits patios and walkways; rebar on a 12–18" grid is better for driveways and structural slabs. Size the steel with the rebar calculator.
Does the calculator support metric units?
Yes — enter dimensions in feet, inches, meters or centimeters, and get results in cubic feet, cubic yards, cubic meters and litres, with weight in kilograms or pounds. Switch between imperial and metric at the top of the calculator.