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Home/Calculators/Pregnancy Calculator
Calculators

Pregnancy Calculator

Estimate gestational age and due dates from LMP, clinical reference dating or embryo transfer, with a trimester timeline.

  • ⚡FastRuns in your browser
  • ◆PrivateFiles stay on your device
  • ♥FreeNo account required

01 / PURPOSE-SPECIFIC INPUTS

Pregnancy dating reference and progress date

Dating estimates do not confirm pregnancy or replace the established clinical due date. Ultrasound mode accepts reported age, not raw scan measurements.

Advanced assumptions & optional details
Practical examples
  • ACOG methods for estimating the due date

02 / RESULT & INTERACTIVE INSPECTION

Your result, visual model and supporting work

Gestational age at selected reference date · not a diagnosis13 weeks 0 daysDisplay values are rounded separately from internal calculations; read the stated model limits.
Estimated due date
Oct 8, 2026
Dating method
lmp
Progress reference date
Apr 2, 2026
Trimester
First trimester
Days until estimated due date
189
Model conception anchor
Jan 15, 2026

Calendar gestational age at the selected reference date, if the pregnancy is ongoing; this does not establish pregnancy status. Prefilled dates are examples, not personal medical history. Confirm dating with a healthcare professional.

Gestational dating timeline · 40-week due-date reference

0w 0d42w 0d

Inspected position: 13w 0d. This is an illustrative timeline position, not a newly determined medical date.

  • AFirst trimester · 0–13w6d
  • BSecond trimester · 14–27w6d
  • CThird trimester · 28–40w reference
Numbered markers and text identify the same dates without relying on color. Bands describe dating conventions or a stated model window, never a probability distribution.
Formula, worked explanation & limitations
  1. LMP + 280 + (28−28) calendar days; cycle adjustment is approximate, especially with irregular cycles.
  2. Conventional gestational dating starts about fourteen days before the modeled fertilization anchor. Due date and conception dates are estimates, not confirmation of pregnancy or exact delivery timing.
  3. ACOG trimester definitions: first through 13w6d, second 14w0d–27w6d, third from 28w. Timeline milestones are educational references, not diagnoses.
  4. Clinical ultrasound or ART dating may supersede an LMP estimate. Do not average conflicting methods; use the established clinical due date.

How to use Pregnancy Calculator

  1. 1
    Choose a dating method and its reference date

    Enter your values locally; no inputs are uploaded.

  2. 2
    Select the date on which to calculate gestational age

    Check validation feedback before reviewing the browser-generated result.

  3. 3
    Inspect the timeline and compare methods without averaging them

    Review the explanation, copy supported outputs or reset the workspace.

Related tools

CalculatorsConception CalculatorEstimate a fertilization dating anchor from LMP, due date, ultrasound, IVF transfer or a known date, with clear assumptions and private browser-local calculations.→
CalculatorsDue Date CalculatorEstimate pregnancy due dates from LMP, conception, ultrasound dating or IVF transfer, with date-safe gestational progress and a clear milestone timeline.→

About Pregnancy Calculator

Choose a dating method and its reference date. Select the date on which to calculate gestational age. Inspect the timeline and compare methods without averaging them. Read the worked explanation and scope alongside every result.

Benefits

Estimate gestational age and due dates from LMP, clinical reference dating or embryo transfer, with a trimester timeline. Interactive controls inspect the calculated model without silently changing submitted assumptions.

Privacy note

Pregnancy Calculator inputs and calculations remain in browser memory. No external processing API receives entered dates, measurements, coefficients or financial values. Ordinary website page requests may still be logged. Clipboard access occurs only when you choose Copy Result.

Frequently asked questions

Which pregnancy dating references are available?

Use LMP with cycle adjustment, an estimated due date, clinician-reported gestational age on a scan/reference date, or a day-3, day-5 or day-6 embryo transfer. Raw ultrasound measurements are not interpreted.

How does LMP dating work?

The model due date is LMP plus 280 days plus cycle length minus 28 days. Gestational dating begins 280 days before the derived due date; cycle adjustment is approximate.

How is IVF dating calculated?

Estimated due date is transfer date plus 266 minus embryo age in days. A day-5 transfer adds 261 days. The clinic’s established ART dating should guide care.

What do the trimester bands represent?

First trimester runs through 13 weeks 6 days, second from 14 weeks through 27 weeks 6 days, and third from 28 weeks. The 37-week and due-date markers are educational dating references, not diagnoses.

Are two dating methods averaged?

No. The optional comparison reports the entered methods and date difference independently. Clinical dating can supersede an LMP estimate; the calculator does not choose or average conflicting clinical dates.

Does an estimated week confirm an ongoing pregnancy?

No. Progress is calendar arithmetic conditional on an ongoing pregnancy. Dates before the modeled start or beyond 42 weeks receive no current progress assignment, and the tool cannot determine delivery or pregnancy status.