Pregnancy Due Date BMI Calculator for Active Moms-To-Be

Pregnancy Due Date & BMI Calculator for Training Athletes

If you train hard, log your splits, and treat your body like equipment you actually maintain, finding out you're expecting changes the whole game plan. Our pregnancy due date calculator gives you a clean estimate of your due date and gestational age in seconds, so you can map out training cycles, race calendars, and recovery blocks around something a lot bigger than a PR. Pair it with a bmi calculator to see where you're starting from, and you've got the baseline data you need to talk to your OB or coach with confidence. We built this for women who don't want fluff or guesswork, just numbers. Whether you're a marathoner

How to use Pregnancy Due Date & BMI Calculator for Training Athletes

Pick your input date. Choose either the first day of your last menstrual period (LMP) or your known conception date if you've been tracking ovulation.
Enter the date. Drop the date into the field. If your cycle isn't a textbook 28 days, adjust the cycle length so the math actually fits you.
Hit calculate. The tool runs Naegele's rule and returns your estimated due date plus current gestational age in weeks and days.
Check your week. Use the gestational age output to line up training intensity, nutrition tweaks, and check-in appointments.
Re-run as needed. Got an updated dating ultrasound? Pop the new date in and recalculate. Numbers should match what your provider tells you within a few days.
Save the date. Screenshot or jot down the estimate, then plan your training mesocycles and any races around it.

Frequently asked

How accurate is the due date estimate?

It's based on a 280-day pregnancy from your LMP, which is the standard clinical method. Only about 4% of babies actually arrive on the exact date, but most show up within two weeks either side.

Can I keep training during pregnancy?

Most healthy active women can keep moving with some adjustments. Talk to your OB about heart rate, intensity, and contact risk, especially if you were doing high-impact or heavy lifting before.

What if my cycles are irregular?

LMP-based math gets fuzzy with irregular cycles. An ovulation calculator or early dating ultrasound will give you a more reliable starting point.

Should I track BMI during pregnancy?

Standard BMI isn't designed for pregnancy weight gain. Use a bmi calculator for your pre-pregnancy baseline, then follow your provider's recommended gain range based on that starting number.

Does muscle mass mess with the calculation?

Not for the due date itself. But if you're tracking body composition alongside, a body fat calculator gives a better picture than scale weight alone since lean mass shifts your numbers.

Can I still run a calorie deficit?

No. Pregnancy isn't the time for a calorie deficit calculator. You need a small surplus, especially in the second and third trimesters. Save cutting for postpartum recovery.

Is my data stored?

Nope. Everything runs in your browser. Close the tab and the inputs are gone.

Pregnancy Due Date & BMI Calculator for Training Athletes

How to use Pregnancy Due Date & BMI Calculator for Training Athletes

Frequently asked

Tools you might also like

What others are trying

Browse by category

Have an idea for a tool?