How many weeks pregnant am I?

“Weeks pregnant” usually means gestational age counted from LMP in whole weeks plus extra days (for example, 10+3 means 10 weeks and 3 days). If your clinic uses ultrasound-based dating, your week count may shift slightly compared with a simple LMP app result.

The usual counting method (from LMP)

Most consumer tools calculate gestational age from the first day of your last menstrual period. That is the same anchor used for many paper charts: day zero is LMP bleeding day one, and the tool counts forward to “today” to report weeks and days.

Why your app might disagree with your ultrasound paperwork

Ultrasound-based gestational age can differ from LMP-based age early in pregnancy. Clinicians sometimes “move” the pregnancy timeline when early measurements strongly suggest a different ovulation or implantation timing. That does not mean your pregnancy is unhealthy—it means dating is being standardized.

For a week-focused tool, try our pregnancy week calculator and the dedicated how many weeks pregnant am I page.

How trimesters map onto week counts

Trimesters are educational buckets, not rigid medical gates. Still, they help families orient: first trimester roughly weeks 1–13, second 14–27, third 28 until birth. If you are comparing FAQs, read when the second trimester starts and how many trimesters exist for consistent definitions.

Practical tips for comparing numbers at home

Use one anchor at a time. If you flip between “conception mode” and “LMP mode” without noticing, you can accidentally compare unlike timelines. If you are unsure which anchor your clinic uses, ask at your next visit and write the answer in your notes app.

For a written walkthrough of LMP math, see our blog guide on calculating due dates.

Examples and quick calculations

Example: If LMP was 70 days ago, a simple LMP-based count is often reported as 10 weeks + 0 days (depending on inclusive/exclusive day counting in the tool—always read the subtitle text under your result).

Table: “Week bands” are labels, not due-date predictions.

Common misconceptions

• Mistake: confusing fetal age with gestational age. Gestational age is usually larger because it counts from LMP, not from fertilization.
• Mistake: ignoring the “+ days” portion. Two people both “12 weeks” can be different by several days of development.
• Mistake: assuming weeks decide induction timing. Induction plans are medical decisions with many factors.

Planning tips (non-medical)

• Ask your clinic whether paperwork uses LMP dating, ultrasound dating, or both.
• Screenshot your calculator result the day before appointments so you can compare apples-to-apples.
• If nausea, bleeding, or pain is severe, prioritize urgent care over week-count curiosity.

Related guides and tools

Use these internal links to keep learning—each FAQ is written to stand alone, and the calculators help you turn reading into concrete numbers for your next appointment.

Pregnancy due date calculator (home) · Due date by LMP · Pregnancy week calculator · How many weeks pregnant · Blog: calculate due date · Blog index · About

Last reviewed for clarity: May 2026. Always follow your own clinician’s dating, screening schedule, and urgent-care instructions.