Perimeter · Grades 3–5
Perimeter Worksheets
Trace a finger all the way around the shape and add up what you cross. Printable perimeter worksheets for squares, rectangles, triangles, regular polygons, and L-shapes, with missing-side problems from Grade 4.
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What it is
Perimeter is the total distance around the outside of a shape, the sum of all its side lengths.
Why it matters
Picture fencing a yard: what matters is the total length of fence, not the space inside it. That's perimeter, and tracing the outline first is what makes the idea concrete before the formula takes over.
How to do it
- Find the length of every side. Sides with matching tick marks are the same length.
- Add all the side lengths together.
- Shortcuts: a rectangle is 2 × (length + width); a shape with all sides equal is number of sides × side.
Examples by level
- BeginnerFind the perimeter =Answer36 cm
- IntermediateFind the perimeter =Answer68 cm
- AdvancedFind the perimeter =Answer120 cm
Examples are generated by the same engine as the worksheets, so they're always mathematically correct. Built to avoid repeats, not reshuffle the same handful of questions.
Common mistakes
- Adding only two sides of a rectangle instead of all four.
- Adding only the sides that have a number, and missing the ones marked equal by a tick.
- Confusing perimeter with area.
- Using square units (cm²) for a length.
Tips
- Perimeter is a length, so the unit is cm (not cm²).
- Opposite sides of a rectangle are equal.
- If you know the perimeter, take away the sides you know to find the one that is missing.
For parents
Trace a finger all the way around the shape, perimeter is that whole trip.
For teachers
Contrast perimeter and area on the same rectangle so students keep the units straight.
Key vocabulary
- perimeter
- the distance around a shape
- side
- one edge of a shape
- regular polygon
- a shape whose sides are all the same length
Frequently asked questions
- How do you find the perimeter of a rectangle?
- Add all four sides, or use 2 × (length + width).
- What unit is perimeter measured in?
- A length unit like cm or m, not square units.
- What do the small tick marks on the sides mean?
- Sides with matching tick marks are the same length, so one labelled side gives you the others.
- How do you find a missing side when you know the perimeter?
- Take away the sides you know. For a rectangle, halve the perimeter, then subtract the side you have.
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