Pregnancy Calculator: Due Date & Week Tracker

Pregnancy Calculator: Due Date, Gestational Roadmap & Weight Gain | 2026

Pregnancy calculator and due date calculator: due date by last period, IVF transfer due date estimator, pregnancy weight gain by BMI. Signs of early pregnancy detection, term window (37–42 weeks). Client-side only—no data sent.

What This Pregnancy Calculator Does & Who It's For

Calculator Purpose & Outputs

What You'll Get:

Estimated Due Date (EDD): Typically 280 days from LMP (or from ultrasound/conception/IVF logic). Only ~4% of births occur exactly on this date.
Gestational Age: Current pregnancy age in weeks and days, based on LMP-derived dating.
Birth Term Status: Preterm (<37 wks), early term (37–38), full term (39–40), late term (41), or postterm (42+).
Weight Gain Target: Institute of Medicine ranges (e.g. 25–35 lbs for normal BMI) and ideal gain at your current week.
Key Milestones: First ultrasound window, end of 1st trimester, anatomy scan window, early/full/late term dates.
Privacy: No pregnancy or biometric data sent to any server—client-side only.
Calculation Methods:

Due Date: Enter your confirmed EDD.
Last Period (LMP): First day of last period + average cycle length (Naegele-style with adjustment).
Ultrasound: Scan date + gestational age at scan (weeks + days) to derive EDD.
Conception Date: Conception date + 266 days.
IVF Transfer: Transfer date + 261 days (5-day blastocyst) or 263 days (3-day embryo)—IVF transfer due date estimator.
Ideal Users:

Anyone using a due date calculator by last period: Enter LMP and cycle length for EDD and full roadmap.
IVF patients: Use the IVF transfer due date estimator (3-day or 5-day) for precise dating.
People asking "How much weight should I gain?": Enter height and pre-pregnancy weight for pregnancy weight gain by BMI (IOM ranges).
Those curious about signs of early pregnancy detection: See the Detection and Testing section and FAQ; then enter your best available date (LMP or other) into the calculator.
Accuracy & Limitations:

EDD is a statistical center; most births occur within 2 weeks before or after. LMP method assumes regular cycles; ultrasound and IVF are more precise. Weight targets are IOM guidelines, not personalized medical advice. This tool is for educational and planning only—not a substitute for prenatal care.

This pregnancy calculator and due date calculator provides a complete gestational roadmap—not just a single date. Choose your method: due date (confirmed), last period (LMP), ultrasound, conception date, or IVF transfer (3-day or 5-day embryo). Get estimated due date (EDD), current gestational age, birth term status, pregnancy weight gain target by pre-pregnancy BMI, key milestones, and the 37–42 week term window.

Pregnancy Detection and Testing

Detection and Testing: hCG Blood vs Urine

Blood Tests (Serum hCG):

Can detect pregnancy 6–8 days after fertilization. More sensitive than home urine tests and can provide quantitative levels. Used for early confirmation and to monitor doubling in early pregnancy.
Home Urine Tests:

Typically accurate from the day of your missed period (around 4 weeks gestational age). Some "early" kits claim a few days before missed period. For signs of early pregnancy detection, track your period and test after a missed period or with a sensitive early-test kit.
Using the Calculator After a Positive Test:

Once you have a positive test, use your last period date (or conception/IVF date if known) in this pregnancy calculator to get your due date, gestational age, term window, and weight gain target.

Pregnancy tests detect the hormone hCG (human chorionic gonadotropin). Accuracy and timing differ by test type.

Management Pillars: Safe Medication & Prenatal Vitamins

Medication Categories and Prenatal Vitamins

Prenatal Vitamins & B9 (Folic Acid):

Prenatal vitamins—especially B9 (folic acid)—are important: 400–800 mcg daily before and during early pregnancy reduces the risk of neural tube defects. Start folic acid before conception if possible.
Exercise Safety:

Is it safe to exercise during pregnancy? For most people, yes. Moderate aerobic and strength exercise is generally safe and beneficial. Avoid contact sports, high fall risk, and excessive heat. Get clearance from your obstetric or midwifery provider.

Medication in pregnancy is classified (A, B, C, D, X). Category A and B are generally considered safe; C may be used if benefit outweighs risk; D and X are avoided when possible. Always check with your provider before taking any medication.

Due Date Formulas (LMP, Ultrasound, Conception, IVF)

How the Pregnancy Calculator Derives Your EDD

Term Window (37–42 Weeks):

The calculator shows early term (37 wks), full term (39 wks), and late term (41 wks) dates so you can see your delivery window at a glance. Preterm is <37 weeks; postterm is 42+ weeks. Only about 4% of births occur exactly on the EDD—most fall within this window.

Due date calculator logic by method: LMP + 280 days (with cycle-length adjustment for non-28-day cycles). Ultrasound: EDD = scan date + (280 − gestational days at scan). Conception: conception date + 266 days. IVF transfer due date estimator: 5-day blastocyst = transfer date + 261 days; 3-day embryo = transfer date + 263 days. Pregnancy weight gain by BMI follows Institute of Medicine (IOM) guidelines: underweight 28–40 lbs, normal 25–35 lbs, overweight 15–25 lbs, obese 11–20 lbs.

Pregnancy Calculator FAQ

How accurate is my due date?

Only about 4% of births occur exactly on the due date. The estimated due date (EDD) is typically 280 days (40 weeks) from the first day of your last period and is best thought of as the center of a 37–42 week window. Early first-trimester ultrasound can refine the date; IVF transfer dates are among the most accurate because fertilization timing is known. Use this pregnancy calculator to see your EDD, gestational age, and term window.

How much weight should I gain during pregnancy?

Recommended pregnancy weight gain depends on your pre-pregnancy BMI (Institute of Medicine guidelines). Underweight (BMI <18.5): 28–40 lbs. Normal (BMI 18.5–24.9): 25–35 lbs. Overweight (BMI 25–29.9): 15–25 lbs. Obese (BMI ≥30): 11–20 lbs. This pregnancy calculator uses your height and pre-pregnancy weight to show your target range and ideal gain at your current gestational week.

Is it safe to exercise during pregnancy?

For most people, yes. Moderate aerobic and strength exercise is generally safe and beneficial during pregnancy. Avoid contact sports, high fall risk, and activities that raise core body temperature excessively. If you have complications (e.g. placenta previa, preterm labor risk), your provider may restrict exercise. Always get clearance from your obstetric or midwifery provider before starting or continuing a workout routine.

How do I calculate my due date by last period?

Add 280 days (40 weeks) to the first day of your last menstrual period (LMP). If your cycle isn’t 28 days, adjust: for example, a 32-day cycle adds 4 extra days to your EDD. This pregnancy calculator supports LMP plus average cycle length, and also due date, ultrasound, conception date, and IVF transfer methods for a full gestational roadmap.

How is an IVF transfer due date estimated?

For a 5-day blastocyst transfer, add 261 days to the transfer date. For a 3-day embryo transfer, add 263 days. IVF due dates are among the most accurate because the fertilization timeline is known. This pregnancy calculator includes an IVF transfer option with 3-day or 5-day embryo type for an IVF transfer due date estimator.

What are signs of early pregnancy detection?

Early signs can include missed period, nausea, fatigue, tender breasts, and frequent urination. Pregnancy is detected by hCG: blood tests can detect pregnancy 6–8 days after fertilization; home urine tests are typically accurate from the day of your missed period (~4 weeks gestational age). For signs of early pregnancy detection, test after a missed period or with a sensitive early-test kit.

What is preterm vs full term vs late term?

Preterm is before 37 weeks. Early term is 37–38 weeks; full term is 39–40 weeks (optimal window); late term is 41 weeks; postterm is 42+ weeks. This pregnancy calculator shows your current birth term status and the dates for early term, full term, and late term based on your due date.

Pregnancy Calculator: Due Date, Gestational Roadmap & Weight Gain

Method

Pre-pregnancy (IOM weight band)

Roadmap

Weight gain target (IOM)

Milestones

Symptoms & red flags

Red flags — seek urgent care

Detection & testing

Exercise in pregnancy

Medications & prenatal vitamins

Pregnancy Calculator: Gestational Roadmap & Management

Gestational Intelligence

Why a Roadmap Instead of a Single Date

Why Your Term Window Matters

Why Target Gain Isn't One Number

Why the Date You Enter Matters