Area Calculator

Calculate the area of common shapes instantly with step-by-step solutions. Choose from six shape modes:

• Rectangle — Enter length and width to find area
• Triangle — Enter base and height
• Circle — Enter the radius
• Parallelogram — Enter base and height
• Trapezoid — Enter two parallel bases and height
• Regular Hexagon — Enter side length

How to Use This Calculator

1. Select a shape using the buttons at the top
2. Enter the measurements in the input fields
3. See the area immediately with a full step-by-step breakdown

Every calculation shows exactly how the answer was derived, so you can learn the method while getting your answer.

Area Formulas Explained

Rectangle: Multiply length by width. A rectangle measuring 10 by 5 has an area of 50 square units.

Triangle: Multiply the base by the height, then divide by two. The height must be perpendicular to the base — not the length of a slanted side. A triangle with base 8 and height 6 has an area of 24 square units.

Circle: Multiply pi (approximately 3.14159) by the radius squared. A circle with radius 7 has an area of about 153.94 square units.

Parallelogram: Multiply the base by the perpendicular height. Like a rectangle, but the height is the perpendicular distance between the two parallel sides, not the length of the slanted side.

Trapezoid: Add the two parallel bases together, multiply by the height, and divide by two. Think of it as averaging the two bases and then multiplying by height.

Regular Hexagon: Use the formula $A = \frac{3\sqrt{3}}{2} s^2$ where $s$ is the side length. A regular hexagon is made up of six equilateral triangles, which is where the $\frac{3\sqrt{3}}{2}$ factor comes from.

When You’ll Need Area Calculations

Area calculations come up constantly in practical and professional situations:

• Flooring and tiling — Measure your room to figure out how many square feet of hardwood, tile, or carpet you need. Most flooring is sold by the square foot, so an accurate area calculation prevents you from buying too much or making extra trips to the store.
• Painting walls and ceilings — A gallon of paint typically covers about 350 to 400 square feet. Calculate the total wall area (minus windows and doors) to know exactly how many gallons to buy.
• Landscaping — Whether you are laying sod, spreading mulch, or planning a garden bed, you need the area to order the right amount of material. Mulch is typically sold in cubic yards, so you need the area first, then multiply by depth.
• Roofing — Roof area determines how many shingles or how much roofing material you need. Roofers measure in “squares” where one square equals 100 square feet.
• Concrete and paving — Pouring a patio or driveway requires knowing the area to calculate how many cubic yards of concrete to order. Underestimating means a short pour and a weak slab.
• Fabric and sewing — Quilting, upholstery, and other sewing projects require calculating the area of each piece to determine how much fabric to purchase.

Related

Want to understand the geometry behind these formulas? Explore our topic pages:

• Area of Basic Shapes — rectangles, triangles, and parallelograms explained with worked examples
• Area of Circles — derivation of the circle area formula with practice problems
• Area of Polygons — trapezoids, hexagons, and other polygon areas