Transparent method
The formula
Worked example
Example inputs
How to interpret the result
Recommended pregnancy weight gain isn't distributed evenly across the nine months, and expecting a steady, linear pace from week one sets up a false alarm in the first trimester specifically, when total gain is typically quite small even in a perfectly normal, healthy pregnancy.
Before you rely on it
What to check
Compare gain-to-date against a curve that reflects typical pregnancy pacing, not a straight linear projection, especially when judging first-trimester progress.
The common error
Where people go wrong with pregnancy weight gain calculator
Expecting first-trimester weight gain to track a straight-line share of the total recommended gain. Early pregnancy gain is typically much smaller than a linear projection would suggest, and that's the normal, expected pattern, not a sign of a problem.
Sensitivity evidence
How pre-pregnancy weight changes the recommended total pregnancy weight gain
| Pre-pregnancy weight | Recommended total pregnancy weight gain | Recommended gain by this week |
|---|---|---|
| 120 | 30 | 15 |
| 135 | 30 | 15 |
| 150worked example | 30 | 15 |
| 165 | 20 | 10 |
| 180 | 20 | 10 |
Every input, tested
Which input moves the recommended total pregnancy weight gain most
| Input | Tested from | To | Recommended total pregnancy weight gain at each end | Swing |
|---|---|---|---|---|
| Height | 59 | 72 | 15.5 to 30 | 14.5 (48%) |
| Pre-pregnancy weight | 135 | 165 | 30 to 20 | 10 (33%) |
| Current week of pregnancy | 18 | 22 | 30 to 30 | none |
Two variables at once
Recommended total pregnancy weight gain by pre-pregnancy weight and height
| Pre-pregnancy weight \ Height | 52 | 65 | 78 |
|---|---|---|---|
| 120 | 15.5 | 30 | 34 |
| 135 | 15.5 | 30 | 34 |
| 150 | 15.5 | 30 | 34 |
| 165 | 15.5 | 20 | 30 |
| 180 | 15.5 | 20 | 30 |
Step by step
The worked example, input by input
| Input | Value used | What it means |
|---|---|---|
| Pre-pregnancy weight | 150 | Weight before pregnancy, in pounds. |
| Height | 65 | Height in inches. |
| Current week of pregnancy | 20 | Week of pregnancy, 1-40. |
| Recommended total pregnancy weight gain | 30 | |
| Recommended gain by this week | 15 | |
Inputs, definitions and assumptions
Pre-pregnancy weight
Weight before pregnancy, in pounds.
Height
Height in inches.
Current week of pregnancy
Week of pregnancy, 1-40.
Where the inputs come from
Enter your weight before pregnancy, your height and the current week of pregnancy. The tool calculates your pre-pregnancy BMI category and applies the Institute of Medicine 2009 guidance: for a normal-weight woman, about 25 to 35 pounds in total, for underweight women 28 to 40 pounds, for overweight women 15 to 25 pounds and for women with obesity 11 to 20 pounds. Twin pregnancies have different ranges. Use a weight measured before you became pregnant.
When the result stops applying
The ranges are population guidance, not a personal target, and your provider may recommend a different plan for medical reasons. Weight gain varies between women and across trimesters, and early nausea can lower it. The calculation is not for multiple pregnancies or pregnancy after certain conditions. It is not a substitute for prenatal care.
What to compare it with
See pregnancy timing on the due date and pregnancy week calculators, and the BMI calculator for the category. The calorie goal and macronutrient pages are not designed for pregnancy, so ask your provider about nutrition. The conception date and IVF due date pages help with dating.
People also ask
Frequently asked questions
How much weight should I gain in pregnancy?
It depends on your pre-pregnancy BMI: about 25 to 35 pounds for normal weight, less if you started overweight and more if you started underweight.
Is weight gain even across pregnancy?
No. Gains are small in the first trimester, usually 1 to 4 pounds, then about a pound a week for many women in the second and third trimesters.
What if I gain more or less than recommended?
Discuss it with your provider, who can check your health and the baby's growth and advise on nutrition and activity.