This calculator calculates in which trimester of pregnancy you are based on how many weeks you are currently pregnant.
The resulting report will tell you which trimester you are in, how far along you are in that trimester and when the next trimester(s) will begin.
The first trimester is from week 1 through week 13, the second trimester from week 14 to week 27, and the third trimester from week 28 until the end of the pregnancy.