How to Write a Lab Report: Format, Example and Template

Learning how to write a lab report starts with its purpose: a lab report is a structured account of an experiment, covering the question you tested, the method, the results you measured and what they mean. Most university and A-Level reports follow the IMRaD format (Introduction, Method, Results and Discussion), written in the past tense and usually in the passive or impersonal voice.

This guide walks through each section in the order a marker reads it, with the tense and person rules students most often ask about, how to present tables and graphs, and how to write the error analysis and discussion that separate a pass from a first. If you want a specialist to check your data, graphs or discussion, you can get lab report writing help from a tutor who works in your science.

How to write a lab report in 8 steps

1. Read the brief and marking criteria. Note the word limit, the sections required and the referencing style.
2. State the aim and hypothesis in one sentence each.
3. Write the method in the past tense, with enough detail for someone else to repeat the experiment.
4. Process your data. Put raw readings in tables with units and uncertainties, then plot the graphs.
5. Describe the results in words, referring to each table and figure by number.
6. Write the discussion. Explain the trend using theory, compare with literature values and calculate the percentage error.
7. Write the conclusion and abstract last, answering the aim with your key number.
8. Add the title, references and appendices, then check the report against the brief.

What is a lab report?

A lab report is a formal scientific document that records an experiment so another person could repeat it and judge your conclusions. It states an aim or hypothesis, describes the method precisely, presents the data in tables and graphs, analyses uncertainty and interprets the findings against theory. It is assessed on accuracy, clarity and reasoning, not on how much you write.

Lab reports differ from essays in one key way: every claim must be traceable to your data or to a cited source. A strong report reads like a short research paper; a weak one reads like a diary of what happened in the lab.

What is the standard lab report format?

The standard lab report format is Title, Abstract, Introduction, Method, Results, Discussion, Conclusion and References, sometimes with Appendices for raw data. Your department's handbook or the brief always takes priority, so check whether it asks for a separate aims section, a risk assessment, or a combined Results and Discussion before you start writing.

Notice where the weight sits. The Discussion carries the most marks in most rubrics because it shows understanding, so plan your time so it does not get squeezed at the end.

What tense and person should a lab report be written in?

Write the Method and Results in the past tense, because the experiment has already happened ("the solution was heated to 60 °C"). Use the present tense for established facts and theory ("enzymes denature at high temperatures") and for what your figures show ("Figure 2 shows"). Most UK departments prefer the passive or impersonal voice, though some now accept "we".

If your brief says nothing about person, the safe choice is impersonal ("the sample was weighed"). Avoid switching between "I", "we" and the passive within one report, because inconsistency is marked down more often than either choice.

How do you write a lab report title and abstract?

A good title names the variables and the system, such as "The Effect of Temperature on the Rate of Catalase Activity in Potato Tissue". The abstract is written last and summarises the aim, method, key numerical result and conclusion in 150 to 250 words, so a reader can understand the whole study without reading further.

A reliable abstract structure is four sentences or short groups of sentences:

1. The aim or question, in one sentence.
2. The method, in one or two sentences, naming the key technique.
3. The main result, with the actual number and its uncertainty.
4. The conclusion and what it means.

Do not put citations, figures or anything that is not in the main report into the abstract.

How do you write the introduction?

The introduction explains the scientific background, why the question matters and what you expected to find. Move from general theory to your specific experiment, define key terms, cite two or three credible sources, and finish with a clear aim and a testable hypothesis, ideally one that predicts a direction ("rate will increase with temperature up to an optimum").

A useful check: every paragraph in the introduction should earn its place by setting up something you return to in the Discussion. If you explain a theory you never use again, cut it.

How do you write the method?

The method describes exactly what you did, in enough detail that a competent student could repeat the experiment and get comparable results. Write it as continuous past-tense prose, not a numbered recipe, unless your department asks for steps. State quantities, concentrations, equipment models, temperatures, repeats and how variables were controlled.

Include:

• Independent, dependent and control variables, named explicitly.
• Apparatus and materials, with precision where it matters (for example, a ±0.01 g balance).
• The procedure, in the order it was carried out.
• Repeats and controls, including how many trials and why.
• Safety and ethics, only if the brief asks for it or the work involved risk.

Leave out anything obvious ("the beaker was picked up") and anything that did not affect the result.

How do you present results in a lab report?

Present results in clearly labelled tables and graphs, then describe the key patterns in words without explaining them yet. Each table has a numbered caption above it and each graph a numbered caption below it. Columns and axes carry the quantity and unit, such as "Time / s", and values are given to a consistent number of significant figures.

Raw data that would clutter the page goes in an appendix, with processed data (means, rates, calculated values) in the main Results. Write one or two sentences per table or figure that point to the main trend and any anomalies.

How do you write the discussion and error analysis?

The discussion interprets your results: say whether they support the hypothesis, explain why using theory, compare them with published or expected values, and evaluate reliability. Quantify uncertainty where you can, separate random from systematic errors, and suggest specific improvements. Markers reward precise reasoning, so link every claim back to a number in your results.

A structure that works for most reports:

1. Answer the aim. State the main finding and whether the hypothesis was supported.
2. Explain it. Use the theory from your introduction to explain the trend.
3. Compare. Set your value against a literature or theoretical value and give the percentage difference.
4. Evaluate errors. Identify the largest sources of uncertainty and their likely effect.
5. Improve. Suggest specific changes (for example, a water bath instead of a hot plate) and say what each would fix.

Avoid "human error" as an explanation. It is too vague to earn marks; name the specific step and its effect instead.

How do you write a lab report conclusion?

The conclusion answers the aim in two to four sentences: what was found, whether the hypothesis was supported and how confident you are, given the uncertainty. It introduces no new data or discussion. If the brief asks for it, add one sentence on what further work would test the remaining question.

Lab report example: a short worked sample

This short, fictional sample shows how the sections fit together for a typical biology practical: the effect of temperature on catalase activity in potato tissue. The numbers are illustrative.

Title: The Effect of Temperature on the Rate of Catalase Activity in Potato Tissue

Abstract (sample): This experiment investigated how temperature affects the activity of catalase in potato tissue. Potato discs were added to hydrogen peroxide at five temperatures from 20 °C to 60 °C, and the volume of oxygen produced in two minutes was measured with a gas syringe, with three repeats at each temperature. Activity rose to a maximum at 40 °C (mean 24.0 cm³ of oxygen) and fell sharply above it, to 4.0 cm³ at 60 °C. The results support the hypothesis that catalase has an optimum temperature, above which the enzyme denatures.

Results sentence (sample): Table 1 shows that the mean volume of oxygen doubled from 12.0 cm³ at 20 °C to 24.0 cm³ at 40 °C, then fell to 4.0 cm³ at 60 °C.

Discussion sentence (sample): The optimum of 40 °C is close to the value of about 37 °C often reported for catalase, a difference of about 8%, which may be explained by the 10 °C gap between test temperatures; testing every 2 °C between 34 °C and 44 °C would locate the optimum more precisely.

Notice how each section does one job: the results sentence describes, and the discussion sentence explains, compares and suggests an improvement.

Lab report template you can copy

Use this skeleton and replace each prompt with your own content. Check your brief first, because some departments rename or merge sections.

• Title: The effect of [independent variable] on [dependent variable] in [system].
• Abstract: aim; method in one or two sentences; key result with a number; conclusion.
• Introduction: background theory with citations; why it matters; aim; testable hypothesis.
• Method: materials; procedure in past tense and full sentences; variables (independent, dependent, controlled); safety.
• Results: numbered tables and graphs with units and uncertainties; one or two sentences describing each.
• Discussion: answer the aim; explain with theory; compare with an accepted value and percentage error; evaluate errors; suggest improvements.
• Conclusion: two to four sentences answering the aim.
• References and appendices: cited sources in your department's style; raw data and long calculations.

How do lab reports differ in chemistry, biology and physics?

The structure is the same, but each subject emphasises different things.

For subject help, see chemistry, analytical chemistry, biology, microbiology, physics and biostatistics for lab data. For general guidance on scientific reports, the University of North Carolina Writing Center's guide to scientific reports is a reliable free resource, and the BIPM SI units page is the official reference for units.

Lab report checklist before you submit

• Title names the variables and the system.
• Abstract includes the key number and is written last.
• Hypothesis is testable and stated at the end of the introduction.
• Method is past tense and repeatable.
• Every table and figure is numbered, captioned and referred to in the text.
• Units and significant figures are consistent.
• Discussion compares with a reference value and quantifies error.
• References follow the style your department uses (often Harvard or APA).
• Word count and file format match the brief.

Common lab report mistakes

• Explaining results in the Results section instead of the Discussion.
• Writing the method as a list of instructions in the present tense.
• Reporting means without the spread or number of repeats.
• Blaming "human error" instead of naming a specific source of uncertainty.
• Claiming results "prove" a hypothesis; data supports or does not support it.
• Copying the lab script into the introduction instead of using cited sources.

When to get help with a lab report

If you understand the experiment but are unsure how to structure the analysis, handle uncertainty calculations or interpret a result that did not match theory, a subject tutor can walk you through it. You can get lab report help from a chemistry, biology or physics specialist who reviews your draft and explains the reasoning, or book live tutoring for a one-to-one session before your deadline.

Our help is feedback and tutoring on your own work, in line with your university's academic integrity policy. See our academic integrity policy for what that means in practice.

FAQs

How long should a lab report be?

Most undergraduate lab reports are between 1,500 and 3,000 words, and A-Level write-ups are often shorter. Follow the word limit in your brief, because markers usually penalise reports that run well over. Tables, figures, references and appendices are normally excluded from the word count, but check your handbook.

Do you write a lab report in first person?

Many UK departments still prefer the impersonal or passive voice ("the solution was heated"), but a growing number accept "we" for clarity. Use whatever your brief or handbook specifies, and if it says nothing, stay impersonal. The key rule is consistency: do not mix "I", "we" and the passive in one report.

What is the difference between a lab report and a research paper?

A lab report documents a set experiment, often one the whole class ran, and is assessed on method, analysis and understanding. A research paper reports original research that adds new knowledge and is judged on its contribution to the field. Both use a similar IMRaD structure, but a research paper needs a fuller literature review.

What goes in the appendix of a lab report?

The appendix holds material that supports the report but would interrupt it: full raw data tables, long calculations, calibration data, instrument printouts and risk assessments. Refer to each appendix in the main text, for example "raw readings are given in Appendix A", and keep processed data in the Results.

How do you calculate percentage error in a lab report?

Percentage error equals the difference between your experimental value and the accepted value, divided by the accepted value, multiplied by 100. For example, a measured g of 9.62 m s⁻² against 9.81 m s⁻² gives a percentage error of about 1.9%. Report it in the Discussion alongside the likely causes.

Should the hypothesis go in the introduction?

Yes. The hypothesis belongs at the end of the introduction, after the background theory that justifies it. State it as a testable, directional prediction where possible, such as "increasing substrate concentration will increase the rate of reaction until the enzyme is saturated".

How many references does a lab report need?

There is no fixed number, but most undergraduate lab reports cite three to eight credible sources: textbooks, peer-reviewed papers and data tables for accepted values. The lab script alone is rarely enough. Use the referencing style your department requires and cite every value or theory you did not derive yourself.

Can I combine the results and discussion sections?

Only if your brief allows it. Some formats, particularly in physics and engineering, use a combined Results and Discussion section, where each result is presented and interpreted in turn. If you are not told otherwise, keep them separate, because that is what most marking rubrics expect.

What is the most important section of a lab report?

The Discussion usually carries the most marks, because it shows whether you understand what your results mean, how reliable they are and how they connect to theory. A clear method and accurate results are essential, but the Discussion is where most students gain or lose the higher grade bands.

Can someone help me write my lab report?

Yes, in the right way. A tutor can explain the experiment, help you structure each section, check your calculations and give feedback on your draft, while the analysis and writing stay your own. That is how FLN's lab report help works, in line with academic integrity rules.

What is the IMRaD format?

IMRaD stands for Introduction, Method, Results and Discussion, the core structure of most lab reports and scientific papers. A full lab report usually adds a title, abstract, conclusion and references around it. Each part answers one question: why, how, what was found and what it means.

How do you write a lab report in APA format?

In APA style, use a title page, an abstract, headings for each section, in-text citations with author and year, and a reference list in APA format. Tables and figures are numbered and given titles. Check whether your instructor wants APA 7 student-paper format, which drops the running head.

What should a lab report cover page include?

A cover page usually shows the report title, your name and student number, lab partners, course name and code, instructor or demonstrator, the date of the experiment and the submission date. Many departments provide a template, so use it if one exists.

How long does it take to write a lab report?

A standard undergraduate lab report usually takes between four and ten hours, including processing data, drawing graphs and writing. The discussion and error analysis take the longest. Starting with the method and results while the experiment is fresh saves time later.

How do you write a lab report introduction?

Start with the general background, narrow down to the specific theory the experiment tests, cite your sources, and end with the aim and a testable hypothesis. Keep it focused on what the reader needs to understand your experiment, usually 15 to 20 percent of the word count.