--- title: "Metric & Imperial Conversion" description: "Understand and use approximate equivalences between metric units and common imperial units (inches, pounds, pints)" canonical: https://lightmysky.com/learn/mathematics/metric-and-imperial-conversion-mt_p6MhZJYYPN source: https://lightmysky.com/learn/mathematics/metric-and-imperial-conversion-mt_p6MhZJYYPN.md retrieved: 2026-10-19 --- > **Agent view.** This is the Markdown twin of the page, for tools and assistants. > When to use this site, and the call that answers each job: https://lightmysky.com/agent-instructions.md > API description (OpenAPI 3.1): https://lightmysky.com/openapi.json · Authentication: https://lightmysky.com/auth.md > Pricing: https://lightmysky.com/pricing.md · Catalog: https://lightmysky.com/llms.txt · Full catalog: https://lightmysky.com/llms-full.txt > Every machine-readable file on this domain: https://lightmysky.com/.well-known/ai-catalog.json > Ask for Markdown with `Accept: text/markdown`, a `.md` address, or `?mode=agent`. # Metric & Imperial Conversion Understand and use approximate equivalences between metric units and common imperial units (inches, pounds, pints) Subject: Mathematics · Area: Measurement · Ages 9 to 10 Page: https://lightmysky.com/learn/mathematics/metric-and-imperial-conversion-mt_p6MhZJYYPN ## Ready when they can - State that 1 inch ≈ 2.5 cm and use this to estimate length in inches - Know that 1 kg ≈ 2.2 pounds and estimate a person's weight in pounds - Convert approximately between litres and pints (1 litre ≈ 1.75 pints) ## Lesson: Metric and imperial: same amount, different numbers Some places measure in metric units, like centimeters, kilograms, and litres. Other places also use imperial units, like inches, pounds, and pints. Both measure the same real-world sizes, just with different numbers. You don't need to be exact. A close estimate is enough. *(drawing: A ruler that is 4 inches long is about 10 cm long. Same ruler, two sets of numbers.)* **Example.** A baby weighs 7 pounds. To estimate kilograms, divide by about 2.2: 7 divided by 2.2 is close to 3.2. So a 7-pound baby weighs a little over 3 kg. **Tip.** Quick trick: to turn kilograms into pounds, double the number, then add a bit more. To turn litres into pints, add three quarters of the number you started with. *(drawing: 2 litres of juice is about 3.5 pints. The pint number is always a bit bigger than the litre number.)* **Recap.** Remember the three swaps: about 2.5 cm to an inch, about 2.2 pounds to a kilogram, and about 1.75 pints to a litre. ## Practice 18 questions on this page, each with its working shown. ## Needs first - [Converting measurement units (age 9+)](https://lightmysky.com/learn/mathematics/converting-measurement-units-age-9-mt_Zks8xyInSG) ## Opens up - [Miles & Kilometres](https://lightmysky.com/learn/mathematics/miles-and-kilometres-mt_3tPI0HqqcN)