A trimester calculator helps in finding out the approximate date of delivery of the child or the date when the child may be born. However this is approximate date and not concrete. There may be difference which may be based on several conditions. There are several assumptions basing on which the trimester calculator is developed and helps people to find out the date of the child birth. The basic assumption on which the trimester calculator is planned and designed is th gestation period of 40 weeks. This gestational period is calculated from the last menstrual period. The assumption of the concept that ovulation occurs two weeks after the first day of last menstrual period forms the basis of such approximate calculation. Hence the rest 38 weeks follows the after the the baby is conceived, as a period of child bearing or pregnancy.Sometimes when there is a process of artificial insemination is involved the date of ovulation or in vitro fertilization can be taken as a  reference date.The trimester calculator asks for some basic information from you in form of open fields. Those specific information are regarding the reference to the the last menstrual period date or specific date in relation to the IVF. By using the trimester calculator the stage of pregnancy  can be guessed and the development stage of the baby can also be estimated.However this is not a guaranteed and accurate process. This is an approximation based on some generally accepted rules. By using the pregnancy trimester calculator, you can get an approximate information about the growth stage of the baby in the womb and also can adopt some specific measures for safety of mother and he child as time progresses. There are few things which the trimester calculator would not be able to tell you. Those things are, if you are going to suffer with morning sickness, which could happen sometimes or may be frequently any time of the day or night. The pregnancy trimester calculator would not be able to tell you  if you are going to blossom.So using this great solution you can keep a track of dietary requirements and supplement accordingly. There are several online trimester calculators available which can help to find out the approximate date. However it is advisable to have an open mind as far as the accuracy of the trimester calculator is concerned.However you should also consult your Obstetrician and Gynecologist to get more advice and implement them accordingly.