To start off with, although there are different ways of interpreting this, I understand a ‘small’ grant to be one with a low budget and small timeframe (< a year), and a large grant to have a big budget and 2-8 year timeframe. For both of these I’m assuming that you’re applying to be the PI and you may or may not be hiring others as part of the grant plan.

So let’s start with small grants.

Some key advantages of small grants are:

• They won’t take as much time to prepare compared to a larger grant.
• They can be helpful for testing out an innovative idea or method which you’re hoping to eventually integrate into a larger grant proposal. If you’re proposing an idea that uses new or unconventional theories or methods in a large grant, reviewers will be reassured if you can show that you’ve already tested these in a smaller project.
• If you’d like to move your research into a different area (theoretically or empirically), small grants can be a useful steppingstone for doing this. If you’re worried that reviewers may be sceptical about awarding you with a large grant for a project that’s a departure from what you’ve done previously, getting a small grant in this new area may be a way of convincing them that you’re well-placed to deal with the change.
• For early career researchers, small grants are a good way to get some grant success on your track record. I’ve talked elsewhere about studies showing that reviewers can be biased towards applicants that have already demonstrated that their previous research has received funding.
• For first-time grant writers, small grants are a great way to start developing your grant writing skills and practice pitching your research ideas to grant reviewers.

And now let’s consider the advantages of large grants:

• They offer you the intellectual breathing space of several years of dedicated research time. This will give you the opportunity to build on and develop your research to an extent that goes far beyond anything offered by a small grant.
• They’ll give you more financial security than a small grant. And if you’re entirely financially reliant on a grant that only lasts for 6-12 months, then you’ll probably end up spending a lot of that time applying for new grants or other jobs.
• They’ll give you the time and space to write a new, large grant proposal at the end of your project (if you want to).

These are just a few key points to consider if you’re wondering whether to apply for a small or large grant in the next step of your career. As with most things in research careers, there isn’t one set path to take, but instead it’s about considering your personal and professional situation and weighing up which choice would work best for you.