Choose an ISEF Project Category in 5 Simple Steps

Choosing the right category for your ISEF project can meaningfully affect your chances of success, and at ISEF, you're fully responsible for that choice. The good news is that it comes down to one principle: pick the category that best fits your project. These five steps walk you through how to get it right.

1. Understand the ISEF Categories

Start by getting familiar with the full range of categories. For 2026, ISEF uses 22 categories:

1. Animal Sciences,

2. Behavioral and Social Sciences,

3. Biochemistry,

4. Biomedical and Health Sciences,

5. Biomedical Engineering,

6. Cellular and Molecular Biology,

7. Chemistry,

8. Computational Biology and Bioinformatics,

9. Earth and Environmental Sciences,

10. Embedded Systems,

11. Energy (Sustainable Materials and Design),

12. Engineering Technology (Statics and Dynamics),

13. Environmental Engineering,

14. Materials Science,

15. Mathematics,

16. Microbiology,

17. Physics and Astronomy,

18. Plant Sciences,

19. Robotics and Intelligent Machines,

20. Software Design,

21. Technology Enhances the Arts,

22. Translational Medical Science.

Each has its own focus areas and subcategories, and reviewing the full official listing before you decide is time well spent. Many projects could plausibly fit more than one, so seeing them all helps you find the truest fit.

2. Assess Your Project's Core Elements

Identify the main focus, methods, and technologies of your research, then match them to the category that captures them best.

A project studying plant genetics likely belongs in Plant Sciences; one building a diagnostic device likely fits Biomedical Engineering. The clearer you are about what your project actually is, the more obvious the category becomes.

If you're still shaping the project itself, our guide to crafting the perfect science fair question helps you define it sharply enough to categorize with confidence.

3. Use ISEF's Two Key Questions

ISEF itself recommends asking two questions to guide your choice, and they're the most useful tool you have:

First, who is most qualified to judge my project? Would a doctor, an engineer, or a computer scientist best understand what I did? This matters more than it might seem. At ISEF, judges are assigned based on their expertise in your chosen subcategory, so selecting well means being evaluated by someone who truly understands your work.

Second, what is the emphasis of my project? What did I actually study, make, or do? If your project could fit several subcategories, choose the primary one rather than defaulting to "Other," which rarely serves you well.

One helpful thing to know: you don't have to compete in the same category at ISEF that you used at your regional or state fair. In fact, most regional and state competitions don't use subcategories at all, so ISEF may be the first time you're choosing at this level of detail.

4. Consider Your Interests and Strengths, and Get Feedback

A category that aligns with what genuinely excites you can boost both your motivation and your performance, so reflect on what draws you most to your project. Then pressure-test your choice with people who know the landscape.

Feedback from mentors, teachers, and peers often surfaces considerations you hadn't weighed, and a mentor who is a past science fair winner can be especially valuable.

5. Analyze Past Projects

Reviewing past winning ISEF projects is one of the best ways to calibrate your choice. Look for projects similar to yours and note which categories they competed in, as it shows you both where your project might fit and the level of competition in each category. The Society for Science maintains a searchable database of past ISEF projects.

Don't Just Pick the "Easiest" Category

It's tempting to game the system, to scan the categories, guess which one looks least competitive, and place your project there hoping for a softer field. It's one of the most common mistakes students make, and it usually backfires.

As covered above, ISEF assigns judges based on your chosen subcategory. So if you slot a machine-learning project into a category just because it seems less crowded, you may end up in front of judges whose expertise doesn't match your work, and a judge who doesn't fully grasp what you did can't fully appreciate it. You lose the chance to be evaluated by someone who understands the significance of your methods and results, which is exactly the person most likely to score you well.

The "less competitive" category is also rarely the advantage it appears to be. Judges are experts in their fields, and a project that's clearly a poor fit for its category tends to stand out for the wrong reasons. You're often better off competing in the right, tougher category, where your work is understood and taken seriously, than winning easy placement in the wrong one and being misread.

Make the Right Call With Expert Help From ScienceFair

Choosing your category is one of many judgment calls where experience makes the difference, and it's exactly the kind of decision our team has made firsthand. Every coach on our team is a past science fair winner who has navigated ISEF's categories, and alongside our Ivy League research mentors, they'll help you place your project where it can win and prepare you for the judges evaluating it.

Ready to take the next step? Schedule a call with our academic advisor.