Converting grams and kilograms

Quick answer

There are 1,000 grams in 1 kilogram. To convert from grams to kilograms, divide by 1,000. To convert from kilograms to grams, multiply by 1,000.

Learning outcome

By the end of this page, you will be able to convert between grams and kilograms using the fact that 1 kilogram = 1,000 grams.

Success signs:

• You can tell that 1 kg = 1,000 g
• You can change 2,500 g into kg
• You can change 3.5 kg into g
• You can solve word problems involving grams and kilograms

Why this matters

Knowing how to convert grams and kilograms helps you in many everyday situations. When you go shopping, you might buy 500 g of apples or 2 kg of rice. When you cook, you might need to measure ingredients in grams or kilograms. In science experiments, you might weigh things and need to change units. This skill helps you understand how much things weigh and compare weights easily.

How it works

Let’s start with a simple idea: 1 kilogram (kg) is the same as 1,000 grams (g).

1. 1 kg = 1,000 g
2. To change from grams to kilograms, you divide by 1,000.
3. To change from kilograms to grams, you multiply by 1,000.

Think of it like this: if you have 1,000 small pieces of a puzzle, they make one big puzzle piece. So 1,000 grams = 1 kilogram.

Examples you can see

Here are some clear examples to help you understand:

Example 1: Converting grams to kilograms

Let’s say you have 3,000 grams of flour.

1. 3,000 ÷ 1,000 = 3
2. So 3,000 g = 3 kg

Example 2: Converting kilograms to grams

You have 4.5 kg of sugar.

1. 4.5 × 1,000 = 4,500
2. So 4.5 kg = 4,500 g

Example 3: Real-world shopping

At the supermarket, you buy 2 kg of potatoes and 750 g of carrots.

1. 2 kg = 2,000 g
2. 2,000 g + 750 g = 2,750 g
3. You bought 2,750 g of vegetables in total.

Example 4: Cooking with weights

A recipe calls for 1.25 kg of rice. You want to know how many grams that is.

1. 1.25 × 1,000 = 1,250
2. So 1.25 kg = 1,250 g

Try it as a mini adventure

The Great Market Challenge

You are going to the market with your parent or carer. You have a shopping list:

• 1 kg of apples
• 500 g of bananas
• 2.5 kg of rice
• 750 g of lentils

Your job is to figure out how many grams of each item you need to buy.

Step 1: 1 kg of apples = ? g

Step 2: 500 g of bananas = ? kg

Step 3: 2.5 kg of rice = ? g

Step 4: 750 g of lentils = ? kg

Step 5: Add all the grams together to find the total weight.

Answers for the challenge:

1. 1 kg = 1,000 g
2. 500 g = 0.5 kg
3. 2.5 kg = 2,500 g
4. 750 g = 0.75 kg
5. Total: 1,000 + 500 + 2,500 + 750 = 4,750 g

Common mistakes

• Mistake: Thinking 1 kg = 100 g
• Why it happens: Confusing the number of zeros
• Fix: Remember: 1 kg = 1,000 g. You can count the zeros: 1,000 has three zeros.

• Mistake: Adding instead of multiplying when changing kg to g
• Why it happens: Not knowing which operation to use
• Fix: Remember: kg to g = multiply by 1,000. g to kg = divide by 1,000.

• Mistake: Forgetting to write the decimal point when converting
• Why it happens: Not thinking about decimal places
• Fix: Write down the number and move the decimal point three places to the left for kg to g, or three places to the right for g to kg.

Parent and carer guide

Here’s how you can help your child learn this:

• Use everyday objects like fruits, vegetables, or toys to show weights in grams and kilograms.
• Ask your child to convert weights during shopping or cooking.
• Use a kitchen scale or bathroom scale to show how much things weigh.
• Practice the conversion by writing numbers and moving decimal points.
• Encourage your child to say out loud, “1 kg = 1,000 g” to help memorise.
• Don’t worry if they make mistakes at first – it’s part of learning!

What to say:

• “Let’s think about how many grams are in a kilogram.”
• “What happens when we multiply by 1,000?”
• “Can you show me how you solved that problem?”

What not to do:

• Don’t make it feel like a test or pressure your child to get everything right.
• Don’t skip the step of checking if the answer makes sense.

Practice questions

1. Convert 2,000 g to kg.
2. Convert 3.5 kg to g.
3. Convert 750 g to kg.
4. Convert 4 kg to g.
5. Convert 1,250 g to kg.

Answers:

1. 2,000 g = 2 kg
2. 3.5 kg = 3,500 g
3. 750 g = 0.75 kg
4. 4 kg = 4,000 g
5. 1,250 g = 1.25 kg

FAQ

How many grams are in 1 kilogram?

There are 1,000 grams in 1 kilogram.

How do I change kilograms to grams?

Multiply by 1,000. For example, 2 kg = 2 × 1,000 = 2,000 g.

How do I change grams to kilograms?

Divide by 1,000. For example, 3,000 g = 3,000 ÷ 1,000 = 3 kg.

Why do we need to know this?

It helps us understand how heavy things are and compare weights when shopping, cooking, or doing science experiments.

What if I have a decimal like 1.5 kg?

You still multiply by 1,000. 1.5 kg = 1.5 × 1,000 = 1,500 g.