Usually about half. It's designed to cover the costs of running a university research program spread across all the projects. So a 10MM project provides 10x the funding that a 1MM project provides. Think things like health insurance for the researchers, covering time between projects, lab capital costs, electricity, administration, accounting, even the cost of writing grants.

There's a valid question of if that number can be smaller, but the general concept makes sense.

Universities typically take 50%