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Pregnancy Calendar and Due Date Calculatorv1.0.0

Estimates due date from five inputs: last menstrual period, conception date, known due date, ultrasound, or IVF transfer, using standard obstetric offsets. Offsets are LMP plus 280 days (cycle-length adjusted), conception plus 266, ultrasound by reported gestational age, and IVF transfer plus 266, 264, or 261 days for day-0, day-3, or day-5 embryos. Returns the due date, current gestational week, estimated conception date, and a trimester milestone timeline.

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Estimate your due date, track pregnancy weeks, and plan milestones with this accurate, user-friendly pregnancy calculator. Enter the first day of your last menstrual period, a known conception date, a provider-given due date, an ultrasound date with gestational age, or an IVF transfer date to generate instant results. Use the timeline to plan prenatal visits, maternity leave, and key preparations.

  • Select a Calculation Method: Last Period, Conception Date, Due Date, Ultrasound Date, or IVF Transfer Date.
  • Enter the required date fields and, if using Last Period, set your Average Cycle Length. Keep 28 days if unsure.
  • Click Calculate to see your estimated due date, current pregnancy week, estimated conception date, and progress percentage.
  • Review the Pregnancy Milestones Timeline to see trimester windows and important developmental points.
  • Use Clear to reset inputs. Adjust values to compare scenarios such as different cycle lengths or ultrasound findings.
  • Last Period (LMP): Add 280 days to LMP and adjust for cycle length.
  • Conception Date: Add 266 days to the conception date.
  • Known Due Date: Subtract 280 days to estimate LMP and backfill the timeline.
  • Ultrasound Date: Add the remaining days to reach 280 days using the reported gestational age.
  • IVF Transfer Date: Add 266 days for day-0, 264 days for day-3, or 261 days for day-5 transfers.

Use these standard obstetric conventions to align your inputs with medical practice. Results reflect typical 40-week gestation measured from LMP, with 38 weeks from conception as a common reference.

  • LMP Method: Due Date = LMP + 280 days − (28 − cycle length).
  • Conception Method: Due Date = Conception Date + 266 days.
  • Known Due Date: LMP = Due Date − 280 days.
  • Ultrasound Method: Due Date = Ultrasound Date + (280 − Gestational Age in days).
  • IVF Method: Due Date = Transfer Date + (266 − Embryo Age in days).
  • Plan prenatal care: schedule visits, screenings, and classes around trimester windows.
  • Prepare for leave: align workplace notifications, maternity or parental leave, and childcare setup with your estimated due date.
  • Organize home readiness: set target dates for a hospital bag, nursery setup, and car seat installation.
  • Track progress: monitor weeks and milestones to understand growth stages and upcoming appointments.
  • Support IVF timelines: map transfer specifics to due date expectations and follow-up care.

Plan with realistic scenarios to see how each method works. For example, enter an LMP of March 1 with a 30-day cycle to generate a slightly later due date than a 28-day cycle. Compare a known conception date to confirm the estimated conception produced by the LMP method. Use an ultrasound date with 12.5 weeks of gestational age to update the projected due date based on fetal measurements. Enter an IVF day-5 transfer date to see how the calculator accounts for embryo age. Adjust inputs to validate that your current week and milestone windows update consistently.

How accurate is the due date? Most pregnancies do not deliver exactly on the due date. Providers often discuss a full-term window rather than a single day. Why does cycle length matter? Longer or shorter cycles shift ovulation timing, which changes the projected conception date and due date. Which method should I use? Use the method that best reflects your most reliable information. Ultrasound dating in the first trimester often refines estimates. Can I use this after IVF? Yes. Select IVF Transfer Date and choose the correct embryo day.

This tool is for general informational purposes only and is not intended to provide medical advice. It does not consider individual health conditions and should not be used as a substitute for professional medical advice, diagnosis, or treatment.

Always seek guidance from a qualified healthcare provider with any questions you may have regarding your health. Do not disregard medical advice or delay seeking care based on information provided by this tool.

If you believe you may be experiencing a medical emergency, contact your doctor or call emergency services immediately.

Inputs, outputs, and what the Pregnancy Calendar and Due Date Calculator computes

The form above accepts the following inputs and produces the outputs listed below. This summary is rendered in the page so the parameters are visible to crawlers, assistive tech, and indexing agents that don't fetch the embedded tool frame.

Inputs

  • Calculation Method · default: Last Period
  • First Day of Last Period (date input)
  • Average Cycle Length (days) (numeric input) · default: 28 · range: 22 to 44
  • Conception Date (date input)
  • Due Date (date input)
  • Ultrasound Date (date input)
  • Gestational Age (weeks) (numeric input) · minimum: 0
  • IVF Transfer Date (date input)
  • Embryo Transfer Day · default: Day-0

Controls

Calculate · Clear

Computation

LMP Method : Due Date = LMP + 280 days − (28 − cycle length).

Worked example

Select a Calculation Method : Last Period, Conception Date, Due Date, Ultrasound Date, or IVF Transfer Date.