Perimeter Calculator instantly finds the boundary length of any shape
rectangle, square, triangle, circle, or polygon.
It supports all units (inch, cm, ft) and shows results with step-by-step precision.
Use it to learn, measure, or verify shapes all in one clean and interactive calculator.
Perimeter Calculator – rectangle, square, triangle, circle, regular polygon.
How to Use the Perimeter Calculator
The Perimeter Calculator is an easy-to-use tool that helps you find the boundary length of any geometric shape — including rectangle, square, triangle, circle, or polygon.
It provides clear step-by-step results in multiple units such as inches, feet, and centimeters.
- Select the shape you want to calculate — for example, Rectangle, Square, or Triangle.
- Enter the required dimensions such as width, height, or side lengths.
- Choose your preferred unit (in, cm, or ft) to get accurate conversions.
- Click the Convert button to display the perimeter instantly along with equivalent values in all supported units.
The calculator automatically adjusts for each mode —
whether it’s a Perimeter Calculator Rectangle (using P = 2w + 2h),
a Perimeter Calculator Square (P = 4a),
or a Perimeter Calculator Triangle (P = a + b + c).
Perimeter Formulas by Shape
The Perimeter Calculator supports all major geometric shapes and applies the correct mathematical formulas automatically.
Here’s a quick reference table showing each formula for perimeter with a practical example.
For more advanced cases, like irregular plots or coordinate-based measurements, you can apply the
distance formula:
d = √((x₂ − x₁)² + (y₂ − y₁)²).
This method helps calculate the perimeter by summing distances between multiple coordinate points on a map or diagram.
💡 Tip: Use fractional or decimal inputs in the calculator for precise Perimeter Calculator Fractions — it supports mixed values and converts them automatically.
Perimeter vs Area – What’s the Difference?
In geometry, perimeter measures the total length around a shape’s boundary, while area measures the space inside that boundary.
This Perimeter Calculator focuses on the outer length; if you need the inside surface, use an area calculator.
If you only know the area and need the perimeter, remember there isn’t a single formula for all shapes
(different shapes can share the same area but have different perimeters). Some cases are solvable with extra info
(e.g., square area → perimeter using side = √area). That’s why “Perimeter calculator from area” works only when the shape is known.
🔎 Looking for areas instead of perimeters? Try our geometry tools:
Note: “How to find volume” relates to 3-D solids and is outside the scope of a perimeter tool. Use our volume calculators when working with
boxes, cylinders, or prisms.
Practical Uses & Real Examples
The Perimeter Calculator is not just a classroom tool — it’s a practical solution for real-world applications.
Whether you’re working with maps, construction layouts, or simple school geometry, this calculator helps ensure accurate and instant perimeter results.
- Land or Map Planning: Use the tool as a map perimeter calculator to estimate the boundary of fields, parks, or land plots using known dimensions or coordinate distances.
- Construction & Fencing Projects: Perfect for builders and landscapers calculating total fence length, garden edges, or walkway borders.
- Education & Practice: Students and teachers can quickly verify answers and understand how formulas apply to real-world measurements.
Compared to tools like Perimeter Calculator Google, this version offers faster results and clearer unit conversions — inches, feet, meters, and centimeters all displayed side by side.
💡 Tip: When planning on maps, measure each segment’s length using coordinates, then sum them with the Perimeter Calculator to get a precise total — perfect for land surveys and outdoor projects.
FAQ – Perimeter Calculator (Quick Answers)
Q1: What is the perimeter formula?
The perimeter formula depends on the shape. For example, a rectangle uses P = 2(w + h), a square uses P = 4a, and a circle (circumference) uses P = 2πr.
In general, perimeter means the total outer length of a 2D shape.
Q2: How do you find the perimeter of a rectangle?
Simply add all sides or use the formula P = 2(w + h).
Example: width = 10 ft, height = 6 ft → P = 2(10 + 6) = 32 ft.
This Perimeter calculator with steps does this automatically for you.
Q3: How to find the perimeter from area?
There’s no single universal formula — you need one dimension (like width or radius).
For a square, if area = 25 m² → side = √25 = 5 → perimeter = 4 × 5 = 20 m.
You can use the calculator by selecting the right shape and entering known values.
Q4: What is the perimeter of a semicircle?
The perimeter of a semicircle is calculated using:
P = πr + 2r.
For example, if r = 4 → P = 3.14×4 + 8 = 20.56 units.
You can check it instantly using this calculator’s “Circle” mode.
Q5: How accurate is this Perimeter Calculator?
All calculations are based on precise geometric formulas with real-time unit conversion.
Results are accurate to two decimal places and can be copied or verified using Google or other geometry tools.
🔗 For more learning resources, see the Wikipedia – Perimeter guide.