Pregnancy Weight Gain Calculator: Quick Check or Weigh-In Tracker
Pregnancy Weight Gain Calculator
& 40-Week ChartSee a typical, healthy weight-gain range for your pregnancy — stated plainly, never graded.
Runs in your browser · nothing saved🌿 How would you like to start?
Pick a path — you can switch between them at any time without re-typing anything.
Either way, everything stays on your device. There’s no account and no server — close the tab and it’s gone.
A gentle, honest note
These ranges reflect general IOM (2009) guidelines by pre-pregnancy BMI — not personalised medical advice. Healthy pregnancies land across and around these ranges for many reasons, and your provider’s specific guidance for you should always take priority.
This tool stays strictly to weight-gain ranges and tracking. It offers no diet, calorie, or exercise guidance of any kind — those belong with your own care team, who know your full picture.
I’m Emma Bennett — I write and maintain this tool from the practical, been-there side of pregnancy. I’m not a medical professional, and the clinical points here reflect published sources rather than personal advice. This tool hasn’t yet been reviewed by a licensed clinician.
Sources: Institute of Medicine / National Academies (2009) weight gain during pregnancy recommendations; ACOG, NHS, and Mayo Clinic guidance on gestational weight gain and BMI.
After building the due date and week calculators, I kept getting the same follow-up question from myself. I had a number on the scale, and no real sense of whether it meant anything.
Most weight tools I tried online either handed me a flat “you’re gaining too much” verdict, or buried the actual guidelines under an ad. I wanted something that just told me the range and let me sit with it, without grading me on the way there.
This pregnancy weight gain calculator does two things, and you choose which one you want right at the start. Use it for a quick check today, one entry, one honest answer, or open the full weigh-in tracker and log a few entries this visit to see an actual trend against the recommended range.
How to use it
Just check today’s numbers. This is the fast path. Enter your pre-pregnancy height and weight, your current weight, and your current week, and you get your BMI category and recommended range immediately. Takes under a minute.
Track my weigh-ins this visit. This opens a small log where you can add a few dates and weights, plotted together on the chart so you can see a trend rather than a single dot. It is clearly stated upfront, this log lives in your browser for the current visit only.
It clears the moment you reload or close the page. Nothing is stored anywhere, which is the same privacy standard every tool on this site holds to, but it does mean this mode is best used in one sitting rather than something you come back to add onto later.
Either way, a few shared steps apply:
- Set your units. Toggle between ft/in and lb, or cm and kg, whichever you think in. Switching does not lose anything you have already entered.
- Enter your height and pre-pregnancy weight. These two numbers set your BMI category, which in turn sets your recommended range for the whole pregnancy.
- Enter your current weight, or your first weigh-in if you are using the tracking mode.
- Choose singleton or twins. The recommended ranges genuinely differ between the two, so this matters more than it might seem.
- Set your current week, using the slider, the arrow buttons, or by syncing a due date or last period date the same way the Pregnancy Week Calculator works. If you do not know your due date yet, the Pregnancy Calculator covers all five ways to work it out, and you can come back here once you have it.
Understanding your results
| What you see | What it means |
|---|---|
| Pre-pregnancy BMI and category | Calculated once from the height and weight you enter before pregnancy weight gain begins. This is what your recommended range is based on. |
| Total range for the whole pregnancy | The full recommended weight gain range for your BMI category, drawn from the IOM 2009 guidelines, the same standard referenced by ACOG and most healthcare providers. |
| Weekly rate, second and third trimester | A gentler week-to-week pace, since most weight gain happens after the first trimester rather than evenly across all 40 weeks. |
| Where you are right now | States your current weight against the recommended range at this stage in plain language. It avoids labels like “on track” or “behind,” since a single number cannot capture the full picture your healthcare provider considers. |
One thing worth understanding clearly: your category is locked in from your pre-pregnancy BMI and does not get recalculated as the pregnancy progresses. That is intentional and matches how the guidance itself is meant to be read, not a limitation of the tool.
Reading the chart
The chart shows your recommended range as a soft band across all 40 weeks, with your own entries plotted on top as a line, and your current week marked clearly. If a chart is not the easiest way for you to take this in, there is a text version available underneath it that reads out the same information in plain sentences.
If you want a copy to keep or bring to an appointment, use the print button. It saves cleanly to PDF from any browser’s print dialog, there is no separate PDF export needed for that.
Tracking multiple weigh-ins
If you chose the tracking mode, you can log a date and weight each time you check in during this visit, and each entry maps automatically to a pregnancy week so it lines up correctly on the chart. This is meant for seeing a trend within one sitting, comparing where you started against where you are now, not as a running log across weeks or months, since nothing here persists once you leave the page.
Twins and multiples
If you are carrying twins, switch that toggle before reading your range. IOM guidelines set meaningfully higher recommended totals for twin pregnancies than for a single baby, and using the singleton range by mistake would give you a number that does not actually apply to you.
Questions people ask me
Is this pregnancy weight gain calculator free?
Yes, completely, no sign-up and nothing saved, same as every tool on this site.
Does it work in kilograms, not just pounds?
Yes, the unit toggle switches the entire tool between ft/in and lb, or cm and kg, cleanly in either direction.
Why doesn’t my range change as my pregnancy goes on?
Because it is based on your pre-pregnancy BMI, which is fixed by definition. What does change week to week is where your current weight sits relative to that fixed range, which is what the “where you are right now” section shows.
How is a twin pregnancy range different?
IOM recommends a higher total weight gain range for twin pregnancies than for a single baby, reflecting the additional demands of carrying two. Switch the twins toggle before checking your results to see the range that actually applies to you.
Can I get a reminder to check in on my weight each week?
Yes, once you have synced or entered a current week, an option appears to add a weekly weigh-in reminder to your calendar.
About Emma Bennett
I am a blogger, not a doctor or a health professional. I built this calculator the same way I built the others, from wanting a straight answer instead of a graded one. I checked the guidelines here against trusted health sources rather than my own experience, since this is content where getting it right matters more than writing it warmly. You can read more about my background on the about page.
Please read: This calculator reflects general IOM (2009) guidelines by pre-pregnancy BMI, not personalized medical advice. Healthy pregnancies land across and around these ranges for many reasons, and your provider’s specific guidance for you always takes priority. This tool offers no diet, calorie, or exercise guidance of any kind, that belongs with your own care team.
Sources I leaned on
- Institute of Medicine / National Academies (2009), weight gain during pregnancy recommendations
- American College of Obstetricians and Gynecologists (ACOG)
- NHS (United Kingdom)
- Mayo Clinic
