Instantly calculate how far along you are in your pregnancy and which trimester you're in.
Enter the first day of your last menstrual period. The calculator shows your current pregnancy week, trimester, and estimated due date.
Pregnancy is divided into three trimesters: first (weeks 1–12), second (weeks 13–27), and third (weeks 28–40+). Each trimester brings distinct developmental milestones.
Reach for this calculator when you need a standardised health metric to discuss with a healthcare provider or to use as a baseline for a fitness programme. The result gives you a number that carries more meaning than subjective assessments.
The most common mistake is treating the result as a precise measurement rather than an evidence-based estimate. All body metric calculators have margins of error — use the result as a tracking baseline, not a clinical diagnosis.
A personal trainer uses the calculator with a new client to set a measurable starting point. Re-running the calculation at 4-week intervals provides an objective progress metric that supports motivation and programme adjustments.
The LMP method is accurate within ±2 weeks. Only 5% of babies are born exactly on their due date. First trimester ultrasound is more accurate.
Pregnancy is counted from the first day of your last menstrual period (LMP), not from conception. Week 1 starts on your LMP date even though fertilization hasn't occurred yet.
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