Units of mass and volume

How much it weighs and how much fits

Today two related families of units. You will meet both in the kitchen and in the shop.

Mass — how much something weighs:

• gram (g) — a paperclip,
• kilogram (kg) = 1 000 g — a litre carton of milk,
• tonne (t) = 1 000 kg — a small car.

Volume — how much fits in a container:

• millilitre (ml) — a teaspoon is about 5 ml,
• litre (l) = 1 000 ml — a carton of milk (that one again!).

Notice a lovely thing: everywhere the step is 1 000. Kilo means a thousand — a kilogram is a thousand grams, a kilometre a thousand metres. One step, no memorising.

The conversion rule does not change: to a smaller unit multiply, to a bigger one divide. Only instead of a ruler you will weigh and measure.

Tereza is baking gingerbread with grandma. Recipe: 250 g flour, 100 g sugar, a quarter of a litre of milk. Grandma’s scales show kilograms with marks — Tereza has to know that 250 g is a quarter of a kilo. For the milk there is a measuring jug with marks of 100 ml: a quarter of a litre… a litre is 1 000 ml, a quarter is 250 ml — two and a half marks. The gingerbread turns out. Grandma says that whoever knows conversions can cook from any recipe; whoever does not, only luck will help.

Conversions with a thousand step

Mass:

• kg → g: times 1 000. Example: 2 kg = 2 000 g.
• g → kg: divided by 1 000. Example: 3 000 g = 3 kg.
• t → kg: times 1 000. Example: 5 t = 5 000 kg.

Volume:

• l → ml: times 1 000. Example: 2 l = 2 000 ml.
• ml → l: divided by 1 000. Example: 4 000 ml = 4 l.

Mixed write-up, when it does not come out smoothly:

2 500 g = 2 000 g + 500 g = 2 kg 500 g (you say “two and a half kilos”).

1 250 ml = 1 l 250 ml.

Useful kitchen pieces:

• half a kilo = 500 g, a quarter of a kilo = 250 g,
• half a litre = 500 ml, a quarter of a litre = 250 ml.

Watch a trick — heavier is not bigger: a kilo of feathers fills a whole sack, a kilo of iron fits in a palm. Mass (weight) and volume (space) are two different things, that is why they have two different families of units. Scales measure mass, a measuring jug volume.

The conversion method stays: decide the direction, multiply or divide by a thousand, check the sense (smaller units → bigger number).

Weighing the shopping

Mum bought 2 kg of potatoes, 500 g of carrots and 250 g of butter. How many grams does she carry altogether?

Step 1: I convert to grams: 2 kg = 2 000 g.

Step 2: I add: 2 000 + 500 + 250.

Under each other or in parts: 2 000 + 500 = 2 500, plus 250 = 2 750 g.

Step 3: mixed: 2 750 g = 2 kg 750 g. Almost three kilos — you will feel that in a bag.

Juice into a jug

A jug holds 1 l. I pour 3 glasses of 200 ml and 1 mug of 300 ml. Does it fit?

Step 1: glasses: 3 × 200 = 600 ml.

Step 2: plus the mug: 600 + 300 = 900 ml.

Step 3: I compare with the jug: 1 l = 1 000 ml. 900 < 1 000 → it fits, 100 ml of space is left.

Notice: you can only compare in the same unit. That is why I rewrote the litre as millilitres.

A tonne on a building site

A builder ordered 2 t of sand. A lorry carries 500 kg at once. How many times must it go?

Step 1: I convert tonnes to kilograms: 2 t = 2 × 1 000 = 2 000 kg.

Step 2: I divide: 2 000 ÷ 500 = 4. (How many times does 500 fit into 2 000? 500, 1 000, 1 500, 2 000 — four times.)

Answer: 4 trips.

Again the same recipe: first a shared unit, then calculating.

Practice: now you do it 🎲

Now try it for real. You will see all the questions at once, like on paper. 시작 with ten. When it goes well, add more.

Convert grams, kilograms and litres with millilitres. The step is always 1 000.

Practise the questions

On paper

The best practice is in the kitchen. Ask at home for help at the scales.

1. Convert: 3 kg to g, 1 500 g mixed to kg and g, 2 l to ml, 4 500 ml mixed to l and ml.

2. Find at home three foods with a mass or volume on the packet and copy them. Then sort them from lightest/smallest.

3. A recipe wants 250 ml of milk. You have a measuring jug with marks of 50 ml. How many marks do you pour?

4. A trick to think about: what is heavier — a kilo of feathers, or a kilo of iron? Write the answer and in one sentence why.

Now you 💪

1. You know that kilo = a thousand: 1 kg = 1 000 g, 1 l = 1 000 ml, 1 t = 1 000 kg.
2. Before adding you convert everything to the same unit.
3. You can do a mixed write-up: 2 750 g = 2 kg 750 g.

What to take from this lesson

• Mass: g, kg, t. Volume: ml, l. The step is always 1 000.
• “Kilo” means a thousand — a kilogram is a thousand grams.
• Before calculating, convert everything to the same unit.
• Half a kilo = 500 g, a quarter of a litre = 250 ml — kitchen classics.
• Mass and volume are different things: a kilo of feathers is as heavy as a kilo of iron.

© 2026 Ing. Martin Polak / AlgoRhino · 콘텐츠 이용 약관