It is important to understand the impact arrow weight has on your arrows and their effectiveness when deer hunting. How heavy your arrows should be for deer hunting is fiercely debated in the bow hunting community, but this post should give you the answers you need to know.
The weight needed to ethically harvest a deer when bow hunting depends a lot on more than your arrow, it also depends on the bow you are shooting, and your personal setup. But, here are some basic rules of thumb to go by that will help you have the optimal weight arrow for your specific bow.
The minimum recommended arrow weight is approximately 350 grains. This includes everything. The arrow shaft, nock, fletchings, inserts, broadheads, and anything else that has been added to the arrow. 350 grains is still a fairly light arrow for deer, but 350-400 grains is a fairly common weight range for deer hunting. Light arrows fly faster than heavier arrows but can lack the kinetic energy and penetration capabilities of a heavier setup.
Heavier setups in the 500-600 grain range are very popular due to their impressive momentum and penetration capability, especially when coupled with the right broadhead. Learn more about calculating arrow weight here.
Either way, if you are looking to optimize your arrow weight for deer hunting, you need to look at all the factors that make that arrow perfect for you. This means calculating your arrow speed, kinetic energy, and momentum and then optimizing your arrow weight using what you find after doing those calculations.
Otherwise, if you are just starting out, I recommend using at least a 400-grain arrow for deer hunting using at least a 100-grain broadhead. Lighter arrows fly fast but often lack the penetration capabilities needed for an ethical kill.