Using the scale to convert a measurement on a drawing to the real-life measurement (e.g., 5 cm at 1:50 = 250 cm = 2.5 m).
Where your child meets this in real life: Finding the actual size of a room from an estate agent's floor plan
SEAGReady breaks calculate real-life measurements into 3 steps, taught in order so each skill builds on the last.
Multiply a whole-number drawing measurement by the scale factor to find the real measurement in centimetres
Calculate the real measurement and convert the answer from centimetres to metres
Calculate real measurements when the drawing measurement includes decimals (e.g., 3.5 cm)
Three free sample questions from our calculate real-life measurements course. Every question comes with a full explanation, and hints that guide without giving the answer away.
A floor plan of Belfast City Hall has a scale of 1:50. A hallway measures 3 cm on the plan. What is the real length of the hallway?
Answer: A. 150 cm
Scale 1:50 means 1 cm on the drawing = 50 cm in real life. Real life is bigger, so we multiply. 3 x 50 = 150 cm The hallway is 150 cm long.
Stuck? Start here: What does the scale 1:50 mean? Think about what each number represents.
Ciara is looking at an estate agent's floor plan with a scale of 1:100. The living room measures 4 cm on the plan. How long is the living room in metres?
Answer: A. 4 m
Step 1: Find real length in cm. 4 x 100 = 400 cm Step 2: Convert cm to m. 400 / 100 = 4 m The living room is 4 metres long.
Stuck? Start here: First, find the real length in centimetres using the scale.
Niamh is designing a garden using a 1:100 scale plan. A flower bed measures 2.5 cm on the plan. What is its real length in metres?
Answer: A. 2.5 m
Step 1: Find real length in cm. 2.5 x 100 = 250 cm Step 2: Convert to metres. 250 / 100 = 2.5 m The flower bed is 2.5 metres long.
Stuck? Start here: First multiply the decimal by 100 to find the real length in cm.
This is the exact interactive worked example your child sees in SEAGReady. Step through it and watch the method build up.
Ciaran is looking at a floor plan of his new school. The map has a scale of 1:50.
A corridor measures 4 cm on the plan. What is the real length of the corridor?
4 × 50
Step 1 of 4
Ciaran is looking at a floor plan of his new school. The map has a scale of 1:50.
A corridor measures 4 cm on the plan. What is the real length of the corridor?
The corridor is 200 cm long in real life.
The key insight: Scale drawings are SMALLER than real life, so multiply to find the real size!
Watch out: 4 ÷ 50 = 0.08 cm. Dividing makes it smaller, but real life is BIGGER than the drawing.
These are the misconceptions we see most often in calculate real-life measurements, including the ones our practice questions are specifically designed to catch.
Struggling with calculate real-life measurements? The real gap is often in one of these earlier topics.
SEAGReady finds the exact step where your child gets stuck, teaches it with worked examples like the one above, and brings it back for review so it sticks.