Measuring Lobster Written: by Drew Baumgartner. Ok been meaning to put this up to the tips and tricks area for some time. Some people new to lobster fishing might find this helpful in measuring lobster for legal size. I used a more then legal lobster for this to make the pictures easier to see. Things to know. As of this date November 15, 2007 the legal length of California spiny lobster is 3 1/4 inches from the horn between the eyes to the edge of the carapace. The pictures in this article will show what the definition of these points are. When measuring lobster remember that it is illegal to bring into your boat any lobster that is illegal size (I.E. short). Lobster must be measured on the outside of the boat and immediately released if found to be to short. All related information can be found on the Department of fish and game website here California Department of Fish & Game. How to measure. This isn't easy sometimes and the lobster will not make it any easier. Make sure you have a accurate measuring gauge. Either one bought from the store like a promar or you can make one at home. In these picture I am using a promar lobster only gauge. They make ones that have the crab sizes on the other side but they are rather large. First hold the lobster so you can get to the top of carapace. Now take your gauge and put it in front of and between the eyes of the lobster. Now slide the gauge back toward the tail of the lobster till it stops. This is the forward point for gauging. The gauge shouldn't move back anymore if it does, start from the beginning again till you hit it right. Smaller lobster will be more difficult to get right but take your time and get it right. A ticket for a short is expensive. Once you are in the right place up front then you can push the gauge down in the back of the carapace. This picture shows where the carapace ends and the tail sections begins. Make sure you know the difference. Obviously the tail section will move independently from the carapace. It should have the little hairs at the end of the carapace too. If your gauge is accurate then it is legal if it snaps over the end of the carapace but wiggle this end of the gauge and make sure it can't move from side to side. If it does and it is over the end of the carapace, it is short and needs to go back. Below is a short Lobster. This would be a just legal lobster below. with out any side to side movement. Below is just how much bigger this lobster is then a just legal one. There is no maximum size for lobster only minimum. If you get a few like this one you will have a great night on your hands. Remember you have to carry a gauge device with you when fishing for lobster or you can get a ticket. Good luck and happy hunting.