Short answer: A process diagram is described in four paragraphs: an introduction that paraphrases what the diagram shows, an overview that says how many stages there are, where the process starts and where it ends, then two paragraphs that walk through the stages in order. Write in the present simple, mostly in the passive ("the beans are roasted"), link the stages with sequence words ("once", "after which", "at this stage"), and give no opinion and no explanation of why anything happens. Below: what counts as a process, the structure, a process described step by step with a band 7 model answer of 186 words annotated by criterion, a table of sequence and passive vocabulary, and the five mistakes that cost the most.
The process diagram is the Task 1 type that candidates practise least, because most preparation material shows line graphs and bar charts, and it is the one that punishes that neglect most visibly. There are no figures to cite, so the usual Task 1 reflexes (a trend, a peak, a comparison) have nothing to hold on to, and candidates either list the labels of the diagram without connecting them or start explaining why the process works, which is not the task. The good news is that a process has a fixed shape, and once you know the shape the report almost writes itself.
What a process diagram is
A process diagram shows how something is made, how something happens, or how something works, as a series of stages linked by arrows. Two distinctions matter for the report, and both should appear in your overview.
The first is linear or cyclical. A linear process has a beginning and an end: raw material goes in, a product comes out. A cyclical process returns to its starting point, so the last stage feeds the first: the water cycle, the life cycle of an insect, the recycling of glass. For a linear process you name the first and the last stage; for a cyclical one you say that it is a cycle and name the stage you have chosen to start from.
The second is man-made or natural. A manufacturing process (chocolate, bricks, paper) has machines, containers and people, and is written almost entirely in the passive, because the diagram rarely says who does each action. A natural process (rain, erosion, the growth of a plant) has no agent at all, so it is written in the active with the natural element as the subject: "water evaporates", "the seed germinates". Most diagrams are one or the other; a few mix the two, and the report follows the diagram.
Everything else is common to all Task 1 types: 150 words minimum, about 20 minutes, a report and not an essay, no opinion, and a band on Task Achievement, Coherence and Cohesion, Lexical Resource and Grammatical Range and Accuracy. If you have never written a Task 1, the Writing page on this site has the four Task 1 questions to practise on, and the general shape of a report is the same one described for essays in IELTS Writing Task 2 Structure: Band 7 Templates, 4 Types: introduction, overview, two bodies.
The four-paragraph structure
Paraphrase the question. "The diagram below shows how chocolate is made" becomes "The diagram illustrates the process by which chocolate is produced". Change the verb ("shows" to "illustrates"), change the noun ("how X is made" to "the process by which X is produced"), and add where the process starts and ends if the sentence is short. Do not copy the question word for word: copied words are not counted.
Sentence 1 says whether the process is linear or cyclical and how many main stages it has, and, if there is a natural split, what the groups are (on the farm and in the factory, natural and industrial). Sentence 2 names the first stage and the last. Start with "Overall". This paragraph is the one the examiner looks for first: without it, the report matches the band 5 wording for Task Achievement ("no clear overview"), whatever the rest does.
Walk through the stages in order, one or two per sentence, each linked to the previous one by a sequence word. Say what happens, what it happens to, and, where the diagram shows it, where it happens and with what. Stop at the natural break in the process if there is one (the beans leave the plantation, the raw material enters the machine).
Continue in the same way to the last stage, and close with the end product. No conclusion: a Task 1 report has an overview, not a summary, and a final sentence that begins "In conclusion" repeats the overview and adds nothing.
Count the stages before you write and write the number in the overview. If the diagram numbers them, use its count. If it does not, count the arrows: a stage is a box or picture with an arrow going in and an arrow going out, and a label on an arrow ("transported by lorry") is part of the stage it leads to, not a stage of its own.
A process, described step by step
There is no diagram on this page, so the process is given as a list, in the order the arrows would show it. It is the manufacture of chocolate, a linear, man-made process of eight stages, which are the kind of thing a real diagram labels with a word or two and a picture. Read the list, then the model answer, and notice that the answer adds nothing that is not in the list.
- Ripe red pods are harvested from cacao trees on a plantation.
- The pods are split open and the white beans inside are removed.
- The beans are put into covered containers to ferment.
- The fermented beans are spread out in the sun to dry.
- The dried beans are packed into large sacks and transported by lorry to a factory.
- In the factory, the beans are roasted.
- The roasted beans are crushed and the outer shell is removed.
- The inner part of the bean is pressed, and liquid chocolate comes out.
The band 7 model answer, annotated
The answer follows the four paragraphs above and is written to the band 7 descriptors: a clear overview, every stage covered in order, a range of sequence links, a variety of passive and complex structures with few errors. It is a model to imitate, not an official sample. Word counts are given per paragraph so that you can see the balance.
The diagram illustrates the process by which chocolate is produced from cacao beans, from the harvesting of the pods on the plantation to the pressing of liquid chocolate in a factory.
Task Achievement: the question is paraphrased ("illustrates the process by which ... is produced"), and the start and end of the process are already named, which saves a sentence later. Lexical Resource: "harvesting", "pressing", "plantation" are the diagram's own words turned into nouns.
Overall, the process is linear and consists of eight main stages, which fall into two groups: the first four take place on the plantation, while the remaining four occur in the factory. It begins with the harvesting of ripe pods and ends with the production of liquid chocolate.
Task Achievement: this is the paragraph that separates band 6 from band 7 on a process: linear, eight stages, two groups, first stage, last stage, in two sentences. Coherence and Cohesion: "Overall" signals the overview; the two groups announce the split between the two body paragraphs. Grammar: a "which" clause and a "while" contrast, both error free.
In the first stage, ripe red pods are harvested from the cacao trees. These pods are then split open so that the white beans inside can be removed. Once extracted, the beans are placed in covered containers, where they are left to ferment. After fermentation, they are spread out in the sun to dry.
Task Achievement: stages one to four, each with what happens and what it happens to; the detail the diagram would show (red, white, covered, in the sun) is included. Coherence and Cohesion: four different links, "In the first stage", "then", "Once extracted", "After fermentation", none repeated. Grammar: passive throughout ("are harvested", "are placed", "are left"), a purpose clause ("so that ... can be removed"), a reduced participle clause ("Once extracted"). Lexical Resource: "extracted" and "ferment" rather than "taken out" and "go bad".
The dried beans are subsequently packed into large sacks and transported by lorry to a factory. Here, they are roasted before being crushed, at which stage the outer shell is separated from the inner part of the bean. Finally, this inner part is pressed, and the resulting liquid chocolate is ready for use.
Task Achievement: stages five to eight, ending on the product, and no opinion, no explanation of why the beans are roasted. Coherence and Cohesion: "subsequently", "Here", "before being", "at which stage", "Finally"; "this inner part" refers back rather than repeating. Grammar: "before being crushed" (passive after a preposition), "at which stage" (relative clause), "the resulting liquid chocolate" (participle as adjective). Total: 186 words.
Notice what the answer does not do. It does not say that fermentation develops the flavour, that roasting kills bacteria or that chocolate is popular, because the diagram does not say so and Task 1 asks you to report, not to explain. It does not repeat the overview at the end. And it does not use "then" eight times: the sequence words vary, which is what the Coherence and Cohesion descriptor for band 7 means by "a range of cohesive devices".
Sequence words and the passive
Two sets of language carry a process report. The first is the sequence vocabulary that links one stage to the next; the second is the passive, in its present simple form, with a few variations so that eight sentences do not all read "X is Y-ed". The table gives both, with the form to use and a note on the ones candidates misuse.
| Function | Words and phrases | In a sentence | Note |
|---|---|---|---|
| Opening the sequence | first, in the first stage, to begin with, the process begins when | "In the first stage, the pods are harvested." | "Firstly" is for arguments, not for stages; "first" or "in the first stage" reads better. |
| Moving to the next stage | then, next, after this, after that, subsequently, following this | "The beans are then spread out to dry." | Vary them. "Then" inside the sentence, after the verb "are", is more natural than at the start every time. |
| Linking two stages in one sentence | once, after which, before being, at which stage, at this point, where | "Once dried, the beans are packed into sacks, after which they are transported to a factory." | "Once" plus a past participle ("once dried") is a compact structure that scores on grammatical range. |
| Closing the sequence | finally, in the final stage, the last step is, at the end of the process | "Finally, the inner part is pressed to produce liquid chocolate." | One closing word is enough. "Lastly" is fine; "in conclusion" is not, because there is no conclusion. |
| Present simple passive | is heated, are transported, is removed, are then crushed | "The outer shell is removed and the inner part is pressed." | The basic form. Present, not past: the diagram shows how the process works in general, not one occasion. |
| Passive with a modal or a purpose | can be removed, has to be dried, is left to ferment, in order to be roasted | "The pods are split open so that the beans can be removed." | A purpose clause reports what the diagram shows the stage is for; it does not explain why the process exists. |
| Passive after a preposition | before being crushed, after being roasted, without being washed | "The beans are roasted before being crushed." | Two stages in one clause, with the order kept clear. |
| Active for natural processes | evaporates, rises, condenses, falls, flows, grows | "Water evaporates from the sea, rises and condenses into clouds." | No agent in nature, so no passive. A man-made process uses the active only where the diagram names who acts. |
A useful habit: for each stage, write the verb from the diagram in the passive before you write the sentence. "Harvest" gives "are harvested", "ferment" gives "are left to ferment" or "are fermented", "dry" gives "are dried" or "are left to dry". When the diagram gives you a noun ("fermentation", "roasting"), turn it into the verb, and keep the noun for the next link ("after fermentation").
The five mistakes that cost the most
- Giving an opinion or an explanation. "This process is very efficient", "the beans are roasted to improve the taste", "chocolate is loved all over the world". None of it is in the diagram, and a sentence that is not in the diagram is a sentence the examiner reads as off task. Report what the arrows show and nothing else.
- No overview. The report goes from the introduction straight into stage one. The examiner looks for the overview before anything else, and a missing overview is the band 5 wording for Task Achievement. Write it second, always, and start it with "Overall".
- Miscounting or skipping a stage. The overview says seven stages and the body describes eight, or a stage that had no picture, only a label on an arrow, is missed. Count on the diagram before writing, number the stages on the question paper, and tick each one as you write it.
- The wrong tense. The past simple ("the beans were roasted") describes one occasion; a process diagram describes how something works every time, so it takes the present simple. The exception is a diagram that shows a historical process with dates, which is rare. Check every verb once at the end.
- Copying the labels without connecting them. "Harvesting. Fermenting. Drying. Transporting." rewritten as "The pods are harvested. The beans are fermented. The beans are dried. The beans are transported." is a list with full stops, and it scores on Coherence and Cohesion as one. Link the stages, vary the link, and let a sentence carry two stages where the diagram joins them.
When you have written one, the Task 1 checker on this site returns an estimated band per criterion with the sentences that cost marks. For a process, read the Task Achievement line first: it says whether the overview was found and whether the stages were all covered. The band is an estimate to guide practice, not an official result.
Quick answers
Do I need an overview for a process?
Yes, and it is the paragraph the examiner reads first. For a process the overview says whether the process is linear or cyclical, how many main stages it has, and where it begins and ends; if the stages fall into groups, say so. The public band descriptors for Task Achievement give a clear overview as one of the features of band 7, and a report with no overview matches the band 5 wording on that criterion however good the rest is. Two sentences, starting with "Overall", written second.
Present or past tense?
Present simple, in the passive for a man-made process ("the beans are roasted") and in the active for a natural one ("water evaporates"). The diagram shows how the process works in general, not one occasion, so the past simple is wrong for it. The only common exception is a diagram that shows a historical sequence with dates, which is described in the past. Choose the tense before you write and keep it for every verb.
How many words?
At least 150, which is the official minimum for Task 1, and in practice between 150 and about 190. Under 150 is penalised; there is no upper limit, but every word above the minimum has to be a stage or a link, and a process rarely needs more than four sentences per body paragraph. The model answer on this page has 186 words for eight stages. If you are short, add the detail the diagram shows (where a stage happens, with what), not a comment.
Is the AI band official?
No. The band from the checker is an estimate produced by an AI model against the four official criteria, to guide your practice. Only a certified examiner gives an official IELTS band. This site is independent and not affiliated with, endorsed by or connected to IELTS, the British Council, IDP or Cambridge English.
The short version: one sentence to paraphrase, two sentences of overview with the number of stages and the start and the end, two body paragraphs that walk through the stages in order, present simple, mostly passive, a different link for each stage, no opinion, no explanation, no conclusion. Paste the result and read the Task Achievement line first.