How to summarise a long document
A good summary lets a reader grasp a long document in a fraction of the time without being misled. The method below works for reports, articles, contracts, chapters and meeting notes. It starts with the structure, moves on to the main points and ends with a check against the original, so you do not leave out something that matters.
Decide what the summary is for
Start with the reader and the purpose. A summary for a busy manager needs the decision and the numbers. A summary for revision needs the ideas and the evidence. Write that purpose down in one line, because it tells you what to keep and what to drop.
Skim the structure first
Read the title, the introduction, the headings, the first line of each section and the conclusion. This gives you the shape of the argument before you read the detail. Note how many sections there are and which ones carry the main points.
- Headings and subheadings
- Introduction and conclusion
- Opening sentence of each section
- Tables, charts and their captions
Pull out the key points
Read section by section and write the main point of each in one sentence of your own. Mark the facts, figures, dates and names that the point depends on. Leave out examples, repeated explanations and background the reader already knows.
If the document is very long, work in chunks. Summarise each chapter or section first, then summarise your summaries.
Write the summary
Aim for around a tenth of the original length, or less if the reader is short of time. Put the main conclusion first, then the supporting points in the order of importance. Use plain words, keep each sentence short and do not add your own opinion unless it is asked for.
A text summariser can produce a first draft quickly. Treat it as a starting point and read every line against the source, because a summary can drop a condition or change the emphasis without looking wrong.
Check it against the source
Compare your summary with the original. Are the figures and names exact? Does it say the same thing about certainty, such as "may" or "will"? Is anything important missing? Count the words with a word counter to see that you have met the limit, and ask someone who has not read the document whether the summary makes sense.
Tools mentioned in this guide
Text Summariser
Shorten long text into bullet points or a short paragraph.
TextWord Counter
Count words, characters, sentences and reading time as you type.
TextReading Time Calculator
Estimate how long text takes to read silently or to say aloud, at speeds you choose.
TextText Diff Checker
Compare two texts and see added and removed lines side by side.
Frequently asked questions
How long should a summary be?
A common target is about a tenth of the original, but the reader and the purpose decide. Short enough to be read quickly, long enough to be accurate.
Should I copy sentences from the document?
Use your own words where you can. If you quote, mark it as a quotation and give the source.
Can software summarise for me?
It can give you a first draft, but you must check it against the document. Summaries can leave out conditions or change the emphasis.
What if the document is full of numbers?
Keep the figures that support the main points and state them exactly. Leave out the rest, and say where the full detail can be found.