Geometry Calculator: How to Calculate Area, Perimeter, Volume, and Angles for Any Shape

Geometry shows up in everyday projects more often than you think — measuring a room for new flooring, calculating how much paint to buy, designing a garden layout, figuring out the volume of a shipping box, or determining the angle for a roof pitch. Whether you are a DIY enthusiast, student, homeowner, or professional, having quick and accurate geometry calculations saves time and prevents costly material mistakes. Use the Geometry Calculator at Today Calculator to compute area, perimeter, volume, and angles instantly.

2D Shapes: Area and Perimeter Formulas

Shape	Area Formula	Perimeter Formula	Common Use Case
Square	s²	4s	Room dimensions, tile layouts
Rectangle	l × w	2(l + w)	Floor plans, garden beds
Triangle	½ × b × h	a + b + c	Roof areas, land plots
Circle	πr²	2πr	Round tables, ponds, pipes
Trapezoid	½(a + b)h	a + b + c + d	Irregular lots, roofs
Parallelogram	b × h	2(a + b)	Landscaping, design

For a quick estimate, try the Basic Math Calculator for simple multiplications, or use the dedicated Geometry Calculator for precise shape-specific calculations.

Real-World Example: Flooring Project

Let us say you are installing hardwood flooring in a rectangular living room that measures 18 feet by 14 feet, with a circular fireplace hearth that has a 3-foot radius in the corner. Here is how you calculate how much flooring to buy:

1. Calculate room area: 18 × 14 = 252 sq ft
2. Calculate hearth area (circle): π × 3² = 28.27 sq ft
3. Subtract hearth: 252 − 28.27 = 223.73 sq ft
4. Add 10% waste factor: 223.73 × 1.10 = 246.1 sq ft

Our Percentage Calculator makes adding the waste factor easy, and the Geometry Calculator handles both rectangular and circular area calculations.

3D Shapes: Volume and Surface Area

Shape	Volume Formula	Surface Area Formula	Common Use Case
Cube	s³	6s²	Storage boxes, shipping crates
Rectangular Prism	l × w × h	2(lw + lh + wh)	Rooms, tanks, aquariums
Sphere	⁴⁄₃πr³	4πr²	Balloons, tanks, planets
Cylinder	πr²h	2πrh + 2πr²	Pipes, cans, columns
Cone	⅓πr²h	πr² + πrl	Funnels, traffic cones

Real-World Example: Aquarium Volume

Suppose you have a fish tank that is 48 inches long, 18 inches wide, and 20 inches tall. You want to know how many gallons it holds:

1. Volume in cubic inches: 48 × 18 × 20 = 17,280 cu in
2. Convert to gallons: 17,280 ÷ 231 = 74.8 gallons

Use the Volume Converter to switch between cubic inches, gallons, liters, and other units, and the Geometry Calculator for the initial volume computation.

Angle Calculations

The Geometry Calculator also handles angles. Common angle problems include:

• Finding missing angles in triangles (sum always equals 180°)
• Calculating the slope angle for ramps and roofs
• Determining complementary and supplementary angles
• Working with interior and exterior angles of polygons

For advanced trigonometric calculations involving sine, cosine, and tangent, use the Scientific Calculator alongside the Geometry Calculator.

Start your geometry calculation at Today Calculator’s Geometry Calculator — free, instant, and available on any device.