Reading a bar chart

By the end of this lesson you can read the title, axes, labels and bars of a bar chart, and say what the chart shows in one sentence.

Why it matters

Charts appear in news stories, reports and presentations every day. Reading them correctly, part by part, is how you avoid being fooled, and how you check other people's claims.

The idea in plain words

Reading a chart is like reading a map. Before you follow the roads, you check the title (which town?), the scale (how far is 1 cm?) and the key. A bar chart has six parts to check, always in this order:

1. Title: what the chart is about.
2. Subtitle: the units (people? naira? tonnes?) and the time.
3. Axis: the line of numbers that gives the scale. Check where it starts.
4. Labels: what each bar stands for.
5. Bars: the length or height of each bar is its value.
6. Source: where the data came from, so you can check it.

Bar chart: a chart where each group gets one bar, and the bar's length shows its value. Bars can stand up (a column chart) or lie on their side.

Axis: the line along the side or bottom of a chart with the scale of numbers marked on it.

Check all six parts before you trust what the bars seem to say.

See it done

Data: country-indicators.csv. This is real data about 17 countries from every continent, from Our World in Data. Import it into a new tab, as you did for Lucía's survey: File, Import, Upload, then Insert new sheet(s). One row is one country in one year.

Lucía's class in Bogotá is learning about countries around the world. A pupil asks, "Which country has the most people?" Lucía opens the real data to answer.

Here is a bar chart of its population numbers for 2024.

Population of 17 countries in 2024. Nigeria is marked in amber.

Read it part by part:

1. Title: "Population in 2024". It is about how many people live in each country.
2. Subtitle: "Millions of people, 17 countries, largest first". So 232.7 means 232.7 million people, not 232.7 people.
3. Axis: starts at 0 and goes up in steps of 500 million. Starting at 0 means bar lengths are fair to compare.
4. Labels: country names, one per bar.
5. Bars: India is longest, at 1,450.9 million. China is close behind at 1,419.3 million. Then there is a big drop to the United States, 345.4 million. Qatar is shortest, 3.0 million.
6. Source: UN World Population Prospects, processed by Our World in Data (the source line also names the Global Carbon Budget, which supplies the dataset's CO₂ figures). A real, named source you can check.

Say it in one sentence: "In 2024, India and China each had over 1,400 million people, far more than any of the other 15 countries; Nigeria had about 233 million."

Check a bar yourself. In the country tab, =SUMIFS(E:E,A:A,"Nigeria",D:D,2024) gives Nigeria's 2024 population: 232679482. Divided by 1,000,000 and rounded to one decimal place, that is 232.7 million, just as the bar says. (SUMIFS is SUMIF with more than one condition. You only need to copy it here.)

Your turn, with help

Using the population chart: which country is third largest, and how many people does it have?

Hint: the bars are already sorted, largest first. Count three bars down, and read the number at its end. Remember the unit.

Show the answer

The United States, with 345.4 million people in 2024.

Your turn, alone

1. What was Ghana's population in 2024, according to the chart?
2. How many of the 17 countries had more than 200 million people?
3. Which had more people in 2024, Mexico or Japan? By how many millions?
4. Write one sentence that says what the chart shows about Qatar.

Check your answers

1. 34.4 million.
2. 6 countries: India, China, the United States, Indonesia, Nigeria and Brazil.
3. Mexico: 130.9 − 123.8 = 7.1 million more.
4. For example: "Qatar had the fewest people of the 17 countries in 2024, about 3 million."

Watch out

• Skipping the units. "232.7" means nothing until you read "millions of people". Always read the subtitle.
• Not checking where the axis starts. If it does not start at 0, bar lengths can trick you. Module 5 shows how.
• Reading too much in. This chart shows how many people live in each country. It says nothing about how rich they are or how big the country is.

Say it back

1. Name the six parts of a bar chart to check.
2. In a bar chart, what shows the value?
3. Why should you read the subtitle?

Show the answers

1. Title, subtitle, axis, labels, bars, source.
2. The length (or height) of the bar.
3. It gives the units and the time.

What is next

Bars compare countries in one year. But how did Nigeria's population change, year after year, since 1990? Bars are not the best tool for that. Next lesson: the line chart.

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Data in this lesson: Global Carbon Budget (2025); UN World Population Prospects (2024), processed by Our World in Data. Licensed under CC BY 4.0 (UN data: CC BY 3.0 IGO). Extract and continent labels by DataMedics.