Swollen calf, no pain and not related to exercise. must i worry about a blood clot?

Possible: It sounds less-likely to be a clot (dvt), based on your activity level, though it can happen. May also just be a cyst or something else. Ultrasound should diagnose whatever's wrong, as well as a full history and exam. See your doctor, as it can be very difficult to diagnose based on symptoms alone.

Yes: A swollen leg can occur for many reasons, but a blood clot is one. If you have a blood clot, it needs to be treated. Your leg could be swollen from venous insufficiency (leaky vein valves), problems with the lymph node system, as well as by other problems. The reason to worry about a blood clot, is that untreated, it has the risk of sending a clot to your lung, which can be fatal.

Yes: As dr. Harris said, a blood clot is a possibility. Although as dr. Malkin said, there are many possibilities, but since blood clots can be, and often are, painless, getting an evluation with an ultrasound is a very good idea.

Needs ultrasound.: A swollen leg or part of the leg is a very common complaint. When this occurs, it is imperative to eliminate the most significant potential problem which could be a blood clot. Although there are many other reasons to explain your symptoms, a venous ultrasound is the first step. If negative, then other sources of the swelling can be pursued.