Area Calculator
Calculate area for common plane shapes. Enter rectangle, triangle, circle, and trapezoid dimensions, then compare surface coverage across square units.
Shapes
4 Area Formulas
Outputs
Square Units
Use Cases
Geometry, Layout, Worksheets
Live calculator
Area formula inputs
Calculate rectangle, triangle, circle, and trapezoid area from one worksheet-friendly panel.
Rectangle area
96 cm²
Triangle
30 cm²
Circle
78.539816 cm²
Trapezoid
55 cm²
Rectangle area in other units
| Unit | Converted value | Meaning |
|---|---|---|
| nm² | 9,600,000,000,000,000 | Square nanometers |
| um² | 9,600,000,000 | Square micrometers |
| mm² | 9,600 | Square millimeters |
| cm² | 96 | Square centimeters |
| dm² | 0.96 | Square decimeters |
| m² | 0.0096 | Square meters |
| dam² | 0.0001 | Square decameters |
| hm² | 0 | Square hectometers |
| km² | 0 | Square kilometers |
| mil² | 14,880,029.7601 | Square mils |
| in² | 14.88 | Square inches |
| ft² | 0.1033 | Square feet |
| yd² | 0.0115 | Square yards |
| mi² | 0 | Square miles |
| nmi² | 0 | Square nautical miles |
| pt² | 77,138.0743 | Square points |
| pc² | 535.6811 | Square picas |
Circle area in other units
| Unit | Converted value | Meaning |
|---|---|---|
| nm² | 7,853,981,633,974,483 | Square nanometers |
| um² | 7,853,981,633.9745 | Square micrometers |
| mm² | 7,853.9816 | Square millimeters |
| cm² | 78.5398 | Square centimeters |
| dm² | 0.7854 | Square decimeters |
| m² | 0.0079 | Square meters |
| dam² | 0.0001 | Square decameters |
| hm² | 0 | Square hectometers |
| km² | 0 | Square kilometers |
| mil² | 12,173,695.8801 | Square mils |
| in² | 12.1737 | Square inches |
| ft² | 0.0845 | Square feet |
| yd² | 0.0094 | Square yards |
| mi² | 0 | Square miles |
| nmi² | 0 | Square nautical miles |
| pt² | 63,108.4394 | Square points |
| pc² | 438.2531 | Square picas |
Calculate area for common geometry shapes
Rectangles
Multiply length by width for rooms, grids, worksheets, and rectangular layout problems.
Triangles
Use one-half base times height for right, acute, obtuse, and worksheet triangle examples.
Circles and trapezoids
Calculate circle area from radius and trapezoid area from the average of the two bases.
Area formulas used on this page
Area measures surface coverage in square units. The required dimensions depend on the shape.
Working formulas
Rectangle area
A = length x width
Use for rectangles and squares when both side lengths are known.
Triangle area
A = (base x height) / 2
Height must be perpendicular to the base, not just any side length.
Circle area
A = pi x r^2
Radius is half the diameter and is squared before multiplying by pi.
Trapezoid area
A = ((base A + base B) / 2) x height
Average the parallel bases, then multiply by perpendicular height.
Symbols
- A - area
- The amount of two-dimensional surface covered by the shape.
- r - radius
- The distance from the center of a circle to its edge.
- base - chosen base
- The side or parallel edge used with perpendicular height.
Area results built for formulas and units
Formula-backed results
- The live calculator appears first so users can enter dimensions before reading long explanations.
- Each result stays connected to a visible formula instead of returning a bare number.
- Inputs accept decimals for measurement problems that do not use whole-number dimensions.
- Copy and print controls help users move results into notes, worksheets, and classroom examples.
Geometry guardrails
- Invalid triangle side sets are labeled clearly before Heron's formula is used.
- Circle calculations use radius consistently so diameter, area, circumference, sectors, and arcs agree.
- Shape labels separate area from perimeter so users do not confuse surface coverage with edge length.
- Related links connect the calculator page to the geometry hub and printable formula reference.
Area support for classrooms and practical layouts
Students
Check homework dimensions while keeping the formula and unit meaning visible.
Teachers
Create quick examples for geometry worksheets, board notes, and answer keys.
Printable work
Print the page with inputs, results, formulas, FAQs, and related geometry links.
How it works in three quick steps.
Choose the shape dimensions
Enter length and width, base and height, radius, or trapezoid bases depending on the shape.
Read the area output
Use the result card to compare rectangle, triangle, circle, and trapezoid area values.
Check the formula
Review the formula section to confirm which dimensions were multiplied or averaged.
Save or print area calculations
Copy the result
Copy the calculated measurements and formula context into notes or lesson drafts.
Print the page
Print the calculator result with formula explanations and FAQ support below it.
Compare nearby values
Change one dimension at a time to see how the measurement responds.
About this area calculator
Toolarithm's Area Calculator is designed for the geometry problems that appear most often in worksheets, room layouts, drawing plans, and quick measurement checks. It starts with the shape inputs, then explains the formulas below so the page works both as a tool and as a study reference. The calculator covers rectangle, triangle, circle, and trapezoid area because those formulas form the base for many later geometry topics.
The important distinction on this page is that area measures surface coverage, not edge length. That means results should be read in square units. A rectangle that is 12 by 8 has an area of 96 square units. A triangle with base 10 and height 6 has an area of 30 square units because it covers half of the matching rectangle. The unit tables help users check the same answer across metric, imperial, navigation, and print units without retyping dimensions.
Keep building