Pregnancy
Gestational age
Weeks of pregnancy, counted from the last period rather than from conception. This is the figure every clinical milestone uses.
The Formula
gestational age = days since LMP / 7
Weeks of pregnancy, counted from the last period rather than from conception. This is the figure every clinical milestone uses.
| Symbol | Meaning | Unit | Notes |
|---|---|---|---|
| days | Days elapsed | days | Days from the last period to the date in question. |
| g | Gestational age | weeks | Pregnancy duration in weeks. |
What Each Symbol Means
daysdays
Days elapsed
Days from the last period to the date in question.
gweeks
Gestational age
Pregnancy duration in weeks.
See It Worked With Real Numbers
A formula on its own does not tell you which number goes where. The how to calculate a due date page applies this equation to a concrete case, shows every intermediate step, and names the mistakes that produce a wrong answer even when the algebra is right.
Where This Formula Appears
This equation is the working core of How To Calculate A Due Date, filed under Health. Every number the guide produces comes from substituting into this one line.