Online Area Calculator
Calculate the area of a rectangle, triangle, trapezoid, circle, sector, ellipse, or parallelogram, with results shown in six different units.
| Result | |
|---|---|
| Square Meters | m² |
| Square Footage | ft² |
| Square Inches | in² |
| Square Yards | yd² |
| Acres | ac |
| Hectares | ha |
What Is This Tool?
The Area Calculator finds the surface area of seven common shapes: rectangle, triangle, trapezoid, circle, sector, ellipse, and parallelogram. Pick a shape, enter its dimensions, choose the unit they were measured in, and it returns the area in square meters, square feet, square inches, square yards, acres, and hectares all at once. It uses standard geometric formulas, including Heron's formula for triangles given three sides.
How to Use This Tool?
- Select the shape you want to measure.
- Enter its dimensions in the boxes shown.
- Choose the unit your measurements are in.
- Click Calculate to see the area in every unit.
Key Features
- Covers seven shapes from a single calculator.
- Shows the result in six area units at once.
- Accepts dimensions in eight length units.
- Uses Heron's formula for triangles given three sides.
- Switches shapes instantly with a labeled diagram for each.
Examples
- A 10 × 8 rectangle has an area of 80 square units.
- A triangle with sides 6, 8, and 10 covers 24 square units.
- A circle with radius 13 has an area of about 530.93 square units.
- A 90° sector of a circle of radius 42 covers about 1385.44 square units.
Common Use Cases
- Estimating flooring, paint, or material needed for a surface.
- Working out land or plot size in acres or hectares.
- Checking homework and geometry exercises.
- Sizing fabric, tiles, or panels for a project.
- Comparing the footprint of differently shaped spaces.
Tips & Best Practices
- Measure every dimension in the same unit before entering it.
- For a circle, enter the radius, not the diameter.
- For a triangle, make sure the three sides can actually form a shape.
- For an ellipse, enter the semi-axes, which are half of each full axis.
- Use the matching unit row in the result, since all six are shown.
Limitations
- It covers only the seven built-in shapes.
- Every dimension must be a positive number.
- Triangle sides that cannot form a real triangle give no valid area.
- It assumes ideal, flat shapes with exact measurements.
Frequently Asked Questions
- How is the area of a triangle found from three sides?
- It uses Heron's formula, which works out the area from the three side lengths without needing the height.
- What does the unit setting change?
- It tells the calculator which length unit your dimensions are in, so the area is scaled correctly into every output unit.
- Should I enter radius or diameter for a circle?
- Enter the radius, the distance from the center to the edge, which is half the diameter.
- What is a sector?
- A sector is a wedge of a circle bounded by two radii and an arc, sized by its central angle in degrees.
Key Terminology
- Area
- The amount of surface a shape covers, measured in square units.
- Heron's formula
- A method that finds a triangle's area from its three side lengths.
- Sector
- A wedge of a circle bounded by two radii and the arc between them.
- Semi-axis
- Half the length of an ellipse's major or minor axis.
- Hectare
- A metric unit of area equal to 10,000 square meters.