NIGMS program directors are often asked why most of our grants are made for 4 years. We’ve just posted this brief explanation on our Web site:
NIH is required by Congressional mandate to keep the average research project grant (RPG) length to 4 years. Since NIGMS primarily uses the R01 mechanism for RPGs and participates in few short-term mechanisms (such as the R21), it limits most R01 awards to 4 years.
NIGMS does award some grants for 5 years, including research program projects and centers. The Institute also funds 5-year R01s to most new and early stage investigators to provide extra time for getting their projects under way.
The limitation on the average length of RPGs has been in effect at NIH for more than 10 years, and it helps ensure that funds are available to support new competing awards.
What does it mean for you? Keep applying for project periods that are adequate for the proposed work and are for a maximum of 5 years. But be aware that unless you fall under the exceptions mentioned above, your award will most likely be limited to 4 years of funding.