Area and Volume Calculator
Compute area or volume of common shapes: square, circle, cube, and cylinder.
Inputs
Allowed range: 0 to 1000000
Allowed range: 0 to 1000000
Allowed range: 0 to 1000000
Results
How it works
Square: A = s². Circle: A = π·r², circumference C = 2π·r. Cube: V = s³, surface area S = 6s². Cylinder: V = π·r²·h, surface area S = 2π·r·(r + h).
Complete guide
Area and volume are two of the most frequently needed measurements in everyday life — and two of the most often miscomputed. Area answers 'how much surface?' (paint coverage, floor tile, fabric, lawn fertilizer). Volume answers 'how much space inside?' (water in a tank, concrete for a slab, soil for a planter, shipping container capacity). Getting them right means buying the correct amount of material the first time, not 20% too much or — worse — too little.
This calculator covers the four shapes that account for the vast majority of practical problems: squares, circles, cubes, and cylinders. Each uses an exact closed-form formula, so the only source of error is what you type in. Pick a shape, fill in the dimensions that shape actually needs (the other inputs are ignored), and the calculator returns area or volume plus the related secondary measurement most people also want.
Worked example — circle: a round table has a radius of 0.6 m. Area = π × 0.6² ≈ 1.131 m². If you are buying a tablecloth that needs 10 cm of overhang on every side, recompute with r = 0.7 m and get ≈ 1.539 m². Worked example — cylinder: a water tank with radius 0.5 m and height 1.2 m holds π × 0.5² × 1.2 ≈ 0.942 m³ = 942 liters (since 1 m³ = 1,000 liters).
Unit handling: this calculator is unit-agnostic — whatever unit you put in, the area comes back in unit² and the volume in unit³. Enter everything in meters and you get m² and m³. Enter everything in centimeters and you get cm² and cm³. The one rule is consistency: never mix meters with centimeters in the same calculation. To convert m³ to liters multiply by 1,000; to convert cm³ to liters divide by 1,000; to convert m² to ft² multiply by ≈ 10.764.
Practical tips for buying materials: always add 5–10% to area calculations for waste, cuts, and pattern matching when buying tile, flooring, fabric, or wallpaper. For paint, divide total area by the can's coverage rate (often 10–12 m² per liter for one coat) and round up. For concrete or soil, order by volume and account for compaction — fresh concrete settles slightly, loose soil compresses significantly when watered.
What this calculator does not yet cover: spheres (V = 4/3 · π · r³), cones (V = 1/3 · π · r² · h), pyramids, triangles, trapezoids, and irregular shapes. For irregular shapes, the practical workaround is to decompose them into rectangles and circles, compute each piece, and add the results — exactly what professional estimators do on paper.
Frequently asked questions
- Which value of π is used?
- JavaScript's built-in Math.PI, equal to 3.141592653589793 (about 15 significant digits). That is far more precision than you can measure with any physical ruler, so π is never the source of rounding error in practical answers.
- Can I use it for a sphere, cone, pyramid, or triangle?
- Not in this version — we focus on the four shapes that cover the largest share of practical questions. For a sphere, V = (4/3)π·r³ and surface area = 4π·r². For a cone, V = (1/3)π·r²·h. We may add these in a future update.
- How accurate is the result?
- The formulas are exact mathematical identities, so the only error comes from your input. Measure twice with a tape that has clear millimeter or 1/16-inch markings, and the result will be as accurate as your measurement.
- What is the difference between surface area and lateral surface for a cylinder?
- Lateral surface is just the curved side (2π·r·h) — useful when you are wrapping a label or computing the area of a chimney shaft. Total surface area adds the two circular ends (2π·r² extra), used when you need every face: a closed can, a propane tank, a fully painted column.
- Why do I get slightly different answers from other calculators?
- Usually because the other tool rounded π to fewer digits, rounded intermediate steps, or applied unit conversions silently. Our result keeps full precision until the final display rounding to 4 decimal places.