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

Key takeaways

• Standard lab report structure: Title → Abstract → Introduction → Methods → Results → Discussion → Conclusion → References.
• Methods are written in the past tense. Results present data without interpreting it. The Discussion explains what the data means.
• Label every table (title above) and figure (caption below), and include units and error analysis.

Lab report sections

Title

Concise and specific: "Effect of Temperature on the Rate of Catalase Activity".

Abstract (150–250 words)

A summary of the aim, method, key results (with numbers) and main conclusion. Write it last.

Introduction

Background theory, the purpose of the experiment, and your hypothesis: "If temperature increases up to 37 °C, enzyme activity will increase, then decline at higher temperatures due to denaturation."

Materials and methods

Enough detail that someone could repeat the experiment. Use past tense and passive or first-person voice according to your department's convention. Don't write it as a numbered list of instructions.

Results

Present data in tables and graphs with clear labels, units and uncertainties. Describe trends in text ("Reaction rate peaked at 37 °C"), but don't explain why here.

Discussion

• Interpret the results: do they support the hypothesis?
• Compare with theory and published values
• Analyze sources of error (systematic and random) and their effects
• Suggest improvements and further research

Conclusion

Two or three sentences restating the main finding in relation to the aim.

References

Cite your lab manual, textbook and any literature in your department's style (often APA, ACS or Harvard).

Tips for graphs

• Put the independent variable on the x-axis and the dependent variable on the y-axis
• Label both axes with units
• Add error bars where appropriate
• Use a line of best fit for continuous data. Don't join the dots

Frequently asked questions

What tense should a lab report be in?

Past tense for methods and results, present tense for established theory and for discussing what your results show.

How long should a lab report be?

Typically 1,500–3,000 words for university labs, but follow your course guidelines.

What's the difference between results and discussion?

Results report what you found. Discussion explains what it means and why.