11+ Maths · Geometry & Measurement

11+ Area & Perimeter

Master 2D shape formulas, compound L-shape missing sides, multi-way shape splitting, and shaded border paths. Complete untimed, timed, and Year 4 exam-standard tests.

4 interactive modules
3 practice tests
60+ question bank

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Interactive Area & Perimeter Lab

Interactive Simulation · 4 Modules

Explore live unit grid counts, compound L-shape splitting engines, shaded border calculations, and speed challenge drills.

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11+ Geometry Focus: Master the golden perimeter shortcut on compound L-shapes, avoid confusing perimeter units (cm) with area units (m²), and explore multi-way shape splitting before attempting timed exam tests.
Interactive Simulation

Area & Perimeter Lab

Mode: 2D Shapes

The 11+ Area & Perimeter Guide

Complete 2D shape formulas matrix, inverse dimension solvers, and critical examiner traps.

Master Reference

2D Shape Formulas & Inverse Rules

Commit these foundational formulas to memory. In 11+ exams, questions frequently require working backwards from area or perimeter to find missing side lengths.

ShapePerimeter FormulaArea FormulaInverse Trick
Square4ss²s = P ÷ 4 or s = √Area
Rectangle2(l + w)l × wl = Area ÷ w
Trianglea + b + c½ b × hh = (2 × Area) ÷ b
Parallelogram2(a + b)b × hperpb = Area ÷ hperp
TrapeziumSum of 4 sides½ (a + b) × hAverage of parallel sides × h
The Golden Rule of Units:

Perimeter is distance around a fence (1D: mm, cm, m). Area is carpet covering a floor (2D: mm², cm², m²). Always verify units match before calculating (e.g. convert metres to cm if required).

High-Yield Traps

3 Critical 11+ Geometry Traps

1
The L-Shape Perimeter Trap Exam Trap

Many students mistakenly think cutting a corner out of a rectangle reduces its perimeter. It does NOT! The two cutout edges match the missing corner edges exactly.

Example: An 8 cm by 6 cm rectangle has perimeter 28 cm. If a 2 cm by 3 cm corner is removed, the L-shape perimeter remains 28 cm!
2
The Triangle Slant Height Trap Warning

In non-right triangles and parallelograms, examiners intentionally label the slanted side to trick students. For area, NEVER use the slant side; use the vertical perpendicular height!

Rule: Area = ½ × base × vertical height. Slant side is ONLY used when calculating perimeter!
3
The Double-Border Subtraction Trap Border Rules

When calculating the area of a path or frame surrounding a rectangle, you must subtract the border width twice (once for each side) to find the inner rectangle dimensions.

Formula: Inner L = Outer L - 2(Border) and Inner W = Outer W - 2(Border).
Area & Perimeter Practice Worksheet
Official 11+ printable worksheets with answers
Download PDF ↓

Untimed area & perimeter test

5 questions · drawn from 25 · no timer · unlimited retakes

Work through step-by-step 11+ Area and Perimeter problems at your own pace with detailed solution breakdowns.

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Timed area & perimeter test

5 questions · drawn from 25 · 4 minutes · unlimited retakes

A 4-minute timed test to build speed, accuracy and confidence under exam conditions.

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Year 4 area & perimeter test

5 questions · drawn from 20 · no timer · unlimited retakes

Core foundation test for Year 4 students covering simple rectangular perimeters and basic square counting.

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