3rd Grade Perimeter Worksheet (PDF)

3rd Grade math worksheet: Perimeter – Maths PDF

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This perimeter practice worksheet for 3rd Grade covers perimeter (Common Core 3.MD.D.8), with a free PDF to print.

These 20 problems practice finding the perimeter of polygons, from triangles and rectangles to regular shapes and figures with right angles (Common Core 3.MD.D.8). You will also find unknown side lengths from a perimeter.

Later problems compare rectangles with the same perimeter and different areas, and the last six are word problems. Write the unit with each answer.

Grade 3 · Common Core State Standards: 3.MD.D.8

Perimeter practice worksheet: exercises 1 to 10

Exercise 1 – Triangle perimeter

Find the perimeter of the triangle.

A right triangle.

Exercise 2 – Rectangle perimeter

A flower bed is drawn below. How far is it around the bed?

A rectangle.

Exercise 3 – Square perimeter

Find the perimeter of a square with sides of 12 inches.

Exercise 4 – Four sides

A quadrilateral has sides of 8 yards, 6 yards, 10 yards, and 7 yards. Find its perimeter.

Exercise 5 – Regular pentagon

Find the perimeter of the regular pentagon.

All 5 sides are equal.

Exercise 6 – Regular hexagon

A regular hexagon has sides of 9 centimeters. Find its perimeter.

Exercise 7 – Figure with right angles

All the sides of the figure are labeled. Find its perimeter.

Add all six sides.

Exercise 8 – Missing width

A rectangle has a perimeter of 30 feet and a length of 9 feet. Find its width.

Exercise 9 – Missing triangle side

A triangle has a perimeter of 40 inches. Two sides are 13 inches and 15 inches. Find the third side.

Exercise 10 – Side of a square

A square has a perimeter of 36 centimeters. How long is each side?

Exercises 11 and up

Exercise 11 – Equilateral triangle

An equilateral triangle has a perimeter of 51 feet. Find the length of one side.

Exercise 12 – Missing side of a quadrilateral

The perimeter of the quadrilateral is 34 inches. Find the missing side.

The perimeter is 34 inches.

Exercise 13 – Unlabeled sides

Find the perimeter of the figure. The corners are right angles.

Two sides are not labeled.

Exercise 14 – Same perimeter

Find the perimeter and the area of rectangle A and of rectangle B.

Two rectangles drawn on a grid.

Exercise 15 – Walking around the park

Aisha walks once around a rectangular park that is 120 yards long and 80 yards wide. How far does she walk?

Exercise 16 – Fence for a dog pen

Diego builds a rectangular dog pen 7 feet long and 5 feet wide. Fencing costs $3 for each foot. How much does the fence cost?

Exercise 17 – Ribbon around a frame

Ethan wants to glue ribbon around the edge of a frame that is 14 inches long and 10 inches wide. He has 60 inches of ribbon. How much ribbon is left?

Exercise 18 – Garden with fencing

Maya has 36 feet of fence for a rectangular garden. The garden is 11 feet long. Find its width and its area.

Exercise 19 – Twelve square tiles

Priya arranges 12 square tiles into a rectangle. Each tile is 1 foot on each side. She can make a 1 by 12, a 2 by 6, or a 3 by 4 rectangle. Find the perimeter of each. Which has the smallest perimeter?

Exercise 20 – Poster border

Noah’s rectangular poster has a perimeter of 38 inches and a width of 7 inches. How long is the poster?

Key facts behind this perimeter practice worksheet

Key facts

Perimeter is the sum of the lengths of all the sides of a polygon.
It is measured in plain units, such as inches, feet, or centimeters.
A rectangle has two lengths and two widths: P = 2 × (length + width).
To find a missing side, subtract the known sides from the perimeter.
Rectangles with the same perimeter can have different areas.

How to use this perimeter practice worksheet

Work through the exercises in order: they go from simple to challenging. Write every step on paper, then compare with the solutions page and redo any exercise you missed the next day.

Download the perimeter practice worksheet as a PDF with the button below and keep it with your notes.

All Grade 3 chapters: Grade 3 math.

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Free printable PDF