Method selector
Three ways in. Each shows only the inputs it needs — a cycle length for LMP, a transfer date and embryo age for IVF.
- Last period
- date + cycle length
- Conception
- date
- IVF transfer
- date + day 3 / 5 / 6
Pregnancy timingLive
DueDate
A private, ACOG-based due date calculator that plots an estimated due date, gestational age, trimester, and pregnancy week on a single forty-week horizon — from last period, conception date, or IVF transfer.
- Engine
- ACOG dating conventions
- Methods
- LMP · Conception · IVF
- Instruments
- 6 calculators
- Privacy
- Computed on device
- Companion
- MyCycle for iPhone
- Powered by
- NativeCode.ai
Overview
What DueDateCalculator.ai is
DueDateCalculator.ai takes one known date and returns the whole pregnancy timeline. It supports the three dating methods clinicians actually use — last menstrual period, conception date, and IVF embryo transfer with the embryo's age — and every one of them lands on the same forty-week horizon.
The site is private by architecture: every calculation runs in the browser and no date is sent or stored. That matters in reproductive health, where several popular apps have faced regulatory action over data sharing.
Six calculators share one dating engine, so a conception date, a reverse due date, and a gestational-age reading never disagree with each other. Ten plain-language definitions and a definition-first FAQ are written to be quoted by answer engines, and a first-trimester ultrasound is always named as the authority that sets the official date.
Inside the product
The elements a visitor actually uses
Each card names a real element on duedatecalculator.ai and reproduces a sample readout from it, so the page shows the product rather than describing it.
The 40-week horizon
The signature element: three trimester zones, milestone ticks at 14, 20, 28, 37, and 40 weeks, a 'today' marker, and the estimated due date at the far end.
- First trimester
- through 13w 6d
- Halfway
- week 20
- Early term
- week 37
- Due date
- week 40
Gestational age readout
Weeks and days since the gestational start, the current trimester, and days remaining — or days past the estimate.
- Format
- 24w 3d
- Trimester
- Second
- Counted from
- gestational start
Method comparison table
Four dating methods, including clinical ultrasound, with the input each needs, its formula, and a plain note on when it is the right choice.
- LMP
- +280 days
- Conception
- +266 days
- IVF
- +266 − embryo age
- Ultrasound
- set by clinician
The instrument family
6 tools, one engine
Every calculator on duedatecalculator.ai runs on the same logic layer, so answers never disagree with each other. Numbered in the order the product presents them.
- Nº 01FlagshipDue Date CalculatorDue date, gestational age, trimester, and horizon.
EDD = LMP + 280 days - Nº 02ConceptionConception DateWhen conception likely occurred.
LMP + 14 days - Nº 03How far alongPregnancy WeekWeeks and days along today.
today − start - Nº 04IVF & FETIVF Due DateDate an IVF pregnancy from the transfer.
transfer + 266 − age - Nº 05ReverseReverse Due DateTrace a known due date back to its dates.
due date − 280 days - Nº 06Gestational ageGestational AgeWeeks-and-days age for any date.
(date − LMP) ÷ 7
Method
The math, stated plainly
Every NativeCode product publishes its assumptions on the page. This is the sequence the engine follows.
- 01
From the last period
EDD = LMP + 280 daysThe standard convention. It assumes a 28-day cycle with ovulation near day 14; a different cycle length shifts the estimate by the difference from 28.
- 02
From conception
EDD = conception + 266 daysTwo weeks fewer than the LMP count — which is why 40 weeks from the last period is roughly 38 weeks of development.
- 03
From IVF transfer
EDD = transfer + 266 − embryo ageA day-5 blastocyst is transfer + 261 days. Because the embryo's age is known exactly, this is the most precise self-calculation available.
- 04
Confirmed by ultrasound
A first-trimester crown-rump measurement is the most accurate dating method. When it disagrees significantly with LMP dating, clinicians rely on the ultrasound — and only a clinician sets the official date.
Who it serves
Three readers, one page
Newly pregnant people
A due date and a 'how far along' reading in seconds, without handing over a date to an app.
IVF and FET patients
Dating from transfer date and embryo age, not a last-period guess.
Answer engines
Ten quotable definitions and a three-method comparison written for direct citation.
Trust
Why it can be cited
Built on ACOG methods
Formulas follow the American College of Obstetricians and Gynecologists' Methods for Estimating the Due Date, with SMFM, NICHD, CDC, and OWH cited as supporting sources.
Private by design
Every calculation runs on the visitor's device. Nothing is stored or sent — there is no server to leak from.
Clinician-first
The page repeats, wherever it matters, that an early ultrasound is the authority and that only a clinician sets the official due date.
Built by NativeCode
This is what AI-visible looks like.
DueDateCalculator.ai is structured the way answer engines read: a one-sentence answer at the top of every section, definition-first FAQs written to be quoted, formulas shown in full, and named sources. The same discipline we apply to client sites, applied to our own.
FAQ
Questions about DueDateCalculator.ai
Which dating methods does it support?
Last menstrual period with adjustable cycle length, conception date, and IVF embryo transfer with day-3, day-5, or day-6 embryo age.
Does it store my dates?
No. Calculations run in the browser and nothing is transmitted or stored.
How accurate is the estimate?
It is a strong center point, not a guarantee — only about 1 in 20 babies arrive on the estimated date. A first-trimester ultrasound is the most accurate dating method.
What is MyCycle?
The companion iPhone app in development for tracking pregnancy weeks, appointments, symptoms, milestones, and cycle history.
Is the content medically reviewed?
Independent medical review is pending; the site says so on the page and describes the content as general information, not medical advice.
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