IELTS Reading question type

IELTS Reading Diagram Label Completion: How to Label the Diagram

In IELTS Reading diagram label completion you complete the missing labels on a diagram — of a machine, a building, a natural process — using words from a description in the passage. The skill tested is relating a detailed written description to a picture, then copying the exact words within the word limit.

Updated 3 October 2026 · LingoLeap IELTS Content Team

IELTS Reading diagram label completion at a glance

What you do: Complete the labels on a diagram. The diagram is based on a description given in the text.
Where it appears: IELTS Academic and General Training Reading.
How many questions: IELTS does not fix a number per diagram. The whole Reading test has 40 questions in 60 minutes.
Word limit: Given in the instructions, for example “NO MORE THAN TWO WORDS AND/OR A NUMBER”. You lose the mark for writing more than the limit. Hyphenated words such as “check-in” count as one word.
Order of answers: The answers may not come in the same order as in the text, but they will usually come from one part of the text rather than the whole text.
Marking: Each correct answer receives 1 mark. IELTS says spelling mistakes in Reading are marked as wrong.

IELTS says this type tests whether you can understand a detailed description in the text and relate it to the diagram.
Labels often include a printed word next to the gap (“insulated ___”), which tells you both the meaning and how many words are left.
The diagram's numbering follows the picture, not the passage, so the answers can jump around within the paragraph you need.

Practice: diagram label completion questions with a short passage

An original passage and questions written by LingoLeap in the IELTS style — shorter than a real section, so you can practise this one question type. Give yourself about 9 minutes.

Heating water with the sun

AA solar water heater uses sunlight to warm water for washing and bathing. The commonest domestic design, the flat-plate thermosiphon system, is popular in sunny countries because it has no pump and very few moving parts. It consists of two main components: a collector, which captures the sun's heat, and a tank, which stores the heated water.

BThe collector is a shallow, weatherproof box mounted on a roof and tilted to face the sun. Its top is a sheet of toughened glass, which lets sunlight in but reduces the heat escaping back into the air. Below the glass lies an absorber plate, a thin metal sheet coated with a dark finish so that it absorbs as much radiation as possible. Narrow copper tubes are fixed to the underside of this plate, and water flows through them, picking up heat as it passes. Behind the tubes, a layer of mineral wool stops heat being lost through the back of the box.

CThe heated water does not stay in the collector. Hot water is less dense than cold water, so it rises through the tubes and along a pipe into the top of a storage tank, which is positioned higher than the collector. At the same time, cooler water from the bottom of the tank sinks down a return pipe and enters the lower end of the collector to be heated in turn. This natural circulation, known as thermosiphoning, continues for as long as the sun warms the plate. The position of the tank is essential: if it were lower than the collector, the flow would stop.

DThe tank itself is wrapped in insulation, so that water heated in the afternoon is still usable the next morning. Cold mains water enters near the bottom of the tank, replacing whatever is used, while hot water for the taps is drawn off from the top, where the water is warmest. Because sunshine is never guaranteed, most tanks also contain an electric booster, which switches on only when the water temperature falls below a set level.

EThermosiphon systems are simple and reliable, but they have limitations. A full tank is heavy, so the roof must be strong enough to carry it, and in regions with freezing winters the water in the tubes can freeze. There, systems that use a pump to circulate an antifreeze liquid are more common.

Label the diagram below. Choose NO MORE THAN TWO WORDS from the passage for each answer.

A thermosiphon solar water heater (not to scale). Arrows show the direction of water flow.

Answers explained

Show the answers and why

1. absorber plate — Paragraph B: “Below the glass lies an absorber plate… coated with a dark finish”. The diagram shows the dark layer directly under the glass. “Metal sheet” describes it but is not its name; “absorber plate” is the term the text uses for this part.
2. mineral wool — Paragraph B: “Behind the tubes, a layer of mineral wool stops heat being lost”. “Layer of” is already printed, so “a layer of mineral wool” would repeat it and break the limit. “Insulation” is the general idea, but the text names this layer as mineral wool.
3. tubes — Paragraph B: “Narrow copper tubes are fixed to the underside of this plate”. The label already says “copper”, and the diagram shows several, so keep the plural — “tube” is wrong. Don't write “pipes”: that word is used for something else in the text.
4. storage tank (or tank) — Paragraph C: “a storage tank, which is positioned higher than the collector”; paragraph D: it is “wrapped in insulation”. Both “storage tank” and “tank” fit within two words.
5. return — Paragraph C: “cooler water from the bottom of the tank sinks down a return pipe”. “Pipe” is printed after the gap; “return pipe” in the gap would read “return pipe pipe”.
6. booster — Paragraph D: “most tanks also contain an electric booster”. This is the tricky one: it comes from a different paragraph from labels 1–3, and the diagram shows it only as a zigzag inside the tank.
7. mains — Paragraph D: “Cold mains water enters near the bottom of the tank”. “Cold ___ supply” needs one word to read naturally; “mains water” is also within the limit, but “mains” is the cleanest answer.

How to answer IELTS diagram label completion questions, step by step

1
Study the diagram before the text
Work out what the diagram shows and how it is oriented: which end is the top, which way things flow, which labels are already given. Given labels (“toughened glass”) are your anchors in the text.
2
Find the descriptive paragraph
Answers usually come from one part of the text. Scan for the name of the object or a given label and read that paragraph closely — it is usually full of position words.
3
Follow position language
Words like “below”, “behind”, “on top of”, “at the lower end” and “fixed to the underside” tell you where each part sits. Trace them on the diagram with your finger, part by part.
4
Use the words around each gap
A printed word beside a gap (“copper ___”, “___ pipe”) is copied from the same sentence in the text. Find it, and the answer is next to it.
5
Copy, count and check the form
Copy the exact words, keep plurals, and count: the gap plus the printed words must not push you over the limit.

Common traps

Describing instead of naming

“Dark metal sheet” describes label 1, but the text names it an absorber plate. Use the text's term for the part, within the word limit.

Repeating the printed word

If the label is “___ pipe”, write “return”, not “return pipe”. Repeating printed words is the commonest way to exceed the limit.

Expecting the labels to follow the text

IELTS says answers may not come in the same order as in the text. Labels are numbered around the picture, so label 6 may come from a later paragraph than label 7, or an earlier one.

Confusing similar parts

Texts often use near-synonyms for different parts (tubes in the collector, pipes between collector and tank). Check which part the label points to before you copy.

More practice

Try this question type on the free official IELTS samples next, then a full timed Reading section. LingoLeap's AI-graded practice covers IELTS Speaking and Writing.

Free official IELTS sample questions

FAQ

What is diagram label completion in IELTS Reading?

A Reading task where you complete the labels on a diagram that is based on a description in the passage, using words from the text within a word limit such as NO MORE THAN TWO WORDS AND/OR A NUMBER.

Do diagram labels follow the order of the passage?

Not necessarily. IELTS says the answers may not come in the same order as in the text, but they will usually come from one part of the text.

Do you lose marks for spelling in IELTS Reading?

Yes. IELTS states that spelling mistakes in the Listening and Reading tests are marked as wrong, so copy each word from the passage exactly.

What if my answer is one word over the limit?

You lose the mark. IELTS says you will lose the mark for writing more than the word limit, even if the correct word is included.

Is diagram labelling only in IELTS Academic?

No. IELTS lists diagram label completion as a question type in both Academic and General Training Reading.

Sources

Format, instructions and marking rules are from IELTS (ielts.org). The passage, questions and advice are LingoLeap's own.