Weight-gain calculator
IOM-style gain ranges from your BMI — with a curve and a log.
What it does
The Pregnancy Weight-Gain Calculator & Health Studio works out your pre-pregnancy BMI category and the matching IOM-style recommended total gain range, for singletons and twins. It plots your expected cumulative gain as a trimester progression curve across 40 weeks, keeps an active weekly weight log (with CSV export), supports metric and imperial units, syncs live with a partner or care team by link or QR code, and produces a printable clinical report.
Who it’s for
Expectant parents who want to know "am I roughly on track?" without doom-scrolling — and who like a chart more than a lecture.
How to use it, step by step
- Choose Metric or Imperial, then enter your pre-pregnancy height and weight; tick "Expecting Twins" if that is you.
- Tap Calculate Recommended Gain to see your BMI category and total-gain target range.
- Check the Trimester Curve tab to see the expected cumulative gain at your current week.
- Add weekly entries in the Weight Log — current weight, gestational week, and an optional note for your care team.
- Print the Clinical Report or export the log as CSV before appointments.
What you get
Your BMI category, a recommended total gain range in lbs and kg, a 40-week progression curve, a weekly weight log, and a printable report.
✦ A worked example
You give itPre-pregnancy 5'5" and 135 lbs (a BMI in the normal range).
You getThe IOM-style recommended total gain of roughly 25–35 lbs, a week-by-week target curve, and a log ready for your week-20 weigh-in note.
💡 Tips & tricks
- Log at the same time of day each week (the placeholder note "Normal morning weigh-in" is a good habit) so the curve stays comparable.
- Ranges are guidance, not grades — the report tab is designed to start a conversation with your OB or midwife, not replace one.
Enough reading — the tool itself is one tap away, and it is free.
Try the Weight-gain calculator →