The Area Calculator computes the area of common shapes and converts the result among square units such as square feet, square metres, acres, and hectares. Enter shape dimensions, read area in square units, then change the unit without re-measuring when a plan set and a listing disagree on labels.
Deep per-shape geometry pages cover advanced polygons and 3D surface detail. This Area Calculator owns the everyday multi-shape workflow plus unit conversion for land and floor area in one place.
Calculate the area of any shape
The Area Calculator groups rectangle, circle, and triangle inputs behind one results panel. Pick the shape that matches the region, enter the required lengths in a consistent unit, and read area in square units of that same length unit before converting.
Mixed length units on one shape (feet on width, metres on length) produce nonsense area. Convert every edge to one length unit first, or enter all edges in the unit the form expects. The area number is only as coherent as the inputs.
Composite rooms can be split into rectangles and triangles, areas computed separately, then summed. The Area Calculator handles one simple shape at a time; add the pieces externally when a floor plan is irregular.
Calculate the area of a rectangle
Rectangle area equals length times width when both edges use the same unit.
area = length × widthWorked example: a room 12 ft by 10 ft.
1. Multiply. 12 × 10 = 120 square feet.
2. Metric check if edges were metres. A 4 m × 3 m rectangle is 12 m².
The Area Calculator substitutes the entered length and width into that product and labels the square unit to match. Square inches, square feet, or square metres follow from the edge unit automatically before any acre conversion.
Calculate the area of a circle
Circle area equals π times the square of the radius.
area = π × r²Worked example: radius 5 metres.
1. Square the radius. 5² = 25.
2. Multiply by π. 25 × π ≈ 78.54 m².
If diameter is known instead, radius is diameter ÷ 2. A 10 ft diameter circle has r = 5 ft and area 25π ≈ 78.54 ft². The Area Calculator accepts radius (or diameter when offered) and shows the π substitution rather than hiding it behind a bare number.
Calculate the area of a triangle
Triangle area for base and height equals one-half base times height when height is perpendicular to the chosen base.
area = (1/2) × base × heightWorked example: base 8 m, height 5 m.
1. Multiply base and height. 8 × 5 = 40.
2. Take half. 40 ÷ 2 = 20 m².
Oblique triangles still use perpendicular height, not a slanted side mistaken for height. For side-side-side cases, use a dedicated triangle tool with Heron's formula; this Area Calculator focuses on the base-height case plus unit conversion of the resulting area.
Convert the area between units
Square feet, square metres, square yards, acres, and hectares convert through audited area factors after the shape area is known. One square metre equals about 10.7639 square feet. One square foot equals 0.09290304 square metres exactly from the 0.3048 m foot.
m² = ft² × 0.09290304
ft² = m² ÷ 0.09290304The Area Calculator applies those factors on the unit selector so a 120 ft² room becomes about 11.15 m² without re-entering 12 × 10. Changing units does not change the physical floor; it only changes the number's label.
Calculate land area in acres and hectares
One acre equals 43,560 square feet. One hectare equals 10,000 square metres, about 2.47105 acres. Land listings flip among these labels; the Area Calculator multiplies or divides after square feet or square metres are known. Worked land case: 87,120 square feet.
1. Divide by 43,560. 87,120 ÷ 43,560 = 2 acres.
2. Optional hectares. Convert square feet to m² first, then divide by 10,000, or convert acres with ~2.471 acres per hectare in reverse.
Large parcels measured as rectangles still use length × width, then acre conversion. The Acres to Square Feet Calculator focuses on that pair alone; this Area Calculator adds shape entry before the same land units.
| Square feet | Acres | Approx. m² |
|---|---|---|
| 43,560 | 1 | 4,046.86 |
| 21,780 | 0.5 | 2,023.43 |
| 87,120 | 2 | 8,093.71 |
FAQ
How do I calculate rectangle area?
To calculate rectangle area, multiply length by width in the same unit. For example, 12 ft × 10 ft = 120 ft². The Area Calculator performs that multiply and labels square feet or square metres to match.
How do I calculate circle area?
To calculate circle area, multiply π by the radius squared. For example, r = 5 m gives 25π ≈ 78.54 m². The Area Calculator substitutes π and shows the working.
How do I calculate triangle area?
To calculate triangle area from base and height, compute (1/2) × base × height. For example, base 8 and height 5 yield 20 square units. The Area Calculator uses that base-height formula.
How many square feet are in an acre?
There are 43,560 square feet in one acre. The Area Calculator divides square feet by 43,560 when converting to acres.
How do I convert square feet to square metres?
To convert square feet to square metres, multiply by 0.09290304. The Area Calculator applies that factor when the unit selector moves from ft² to m².
What is a hectare in acres?
One hectare is 10,000 m², about 2.471 acres. The Area Calculator converts through square metres or uses the audited hectare factor when hectares are selected.
Is this the same as geometry shape pages?
Geometry pack pages go deeper on individual shapes. The Area Calculator is the multi-shape hub plus area unit conversion for everyday rectangle, circle, and triangle cases.
Can I enter mixed feet and metres?
No. Convert every edge to one length unit before calculating area. The Area Calculator assumes consistent edge units so the square unit is well defined.
Summary
The Area Calculator computes rectangle area as length × width, circle area as πr², and triangle area as ½ × base × height, then converts among square feet, square metres, acres, and hectares. One acre is 43,560 square feet; one hectare is 10,000 square metres.
Shape inputs need consistent length units, and specialized geometry pages remain available for deeper shape work beyond this hub.