How accurate is a due date calculator?

Due date calculators provide an estimated date based on standard gestational periods; only about 4% of babies are born on the exact estimated due date, so consider the result as a range rather than a fixed date.

Can I use a due date calculator if I conceived through IVF?

Yes, several tools accept IVF transfer date and embryo age (day 3, 5, or 6) to calculate a more accurate due date that accounts for the specific transfer protocol.

What if I don't know the first day of my last period?

If your cycle is irregular or the date is unknown, you can input a conception date or wait for an ultrasound measurement, which many calculators support to estimate gestational age.

Do due date calculators account for cycle length?

Most calculators let you adjust the average cycle length; a longer or shorter cycle shifts the estimated due date accordingly compared to the standard 28-day assumption.

Is the due date the same as the delivery date?

No, the due date is an estimate of when labor may begin; most births occur within a two-week window before or after that date.

Pregnancy & Pediatrics3 options compared

Due Date Calculator

Expecting parents can estimate their baby's arrival using a variety of methods tailored to their specific pregnancy journey. By inputting the date of the last menstrual period, users receive an estimated due date based on standard gestational calculations. The calculator also supports more precise methods, such as utilizing ultrasound results or the specific date of conception, providing...

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Editors’ Top PickBased on community votes

Financial Toolset

financialtoolset.com

Calculate your pregnancy due date using LMP, conception date, IVF transfer, or ultrasound. See trimester milestones a...

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02
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Omni Calculator
omnicalculator.com
This due date calculator estimates the due date based on the first day of the last period or the conception date.
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03
03
Calculator.net
calculator.net
This free due date calculator estimates the due date based on the menstrual cycle, ultrasound, conception date, or IV...
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Side by side

Due Date Calculator options compared

Tool	Best for	Strengths	Limitations
Omni Calculator omnicalculator.com	Quick due date estimate	Simple input for LMP or conception date No ads on the page	Fewer IVF and ultrasound options than others
Financial Toolset financialtoolset.com	IVF and ultrasound tracking	Supports LMP, conception, IVF transfer, and ultrasound methods Shows trimester milestones and important dates	Ads on the page
Calculator.net calculator.net	Basic due date with cycle length adjustment	Estimates due date from LMP, ultrasound, conception, or IVF transfer Includes cycle length selector	Only 1 community vote suggests limited visibility Fewer embryo age options (day 3, 5, 6)

Buyer's guide

How to choose a due date calculator

When picking a due date calculator, first decide what conception method matches your records: last menstrual period, known conception date, IVF transfer, or ultrasound measurement. If you are undergoing fertility treatment, look for a tool that accepts transfer date and embryo age, since standard LMP math does not apply. For a straightforward, ad-free experience, Omni Calculator requires only the first day of your last period or an approximate conception date and delivers a quick estimate. If you need IVF-specific tracking or trimester milestones in one view, Financial Toolset provides those options alongside ultrasound week and day inputs, though its page includes advertisements.

Questions

Due Date Calculator FAQ

How accurate is a due date calculator?: Due date calculators provide an estimated date based on standard gestational periods; only about 4% of babies are born on the exact estimated due date, so consider the result as a range rather than a fixed date.
Can I use a due date calculator if I conceived through IVF?: Yes, several tools accept IVF transfer date and embryo age (day 3, 5, or 6) to calculate a more accurate due date that accounts for the specific transfer protocol.
What if I don't know the first day of my last period?: If your cycle is irregular or the date is unknown, you can input a conception date or wait for an ultrasound measurement, which many calculators support to estimate gestational age.
Do due date calculators account for cycle length?: Most calculators let you adjust the average cycle length; a longer or shorter cycle shifts the estimated due date accordingly compared to the standard 28-day assumption.
Is the due date the same as the delivery date?: No, the due date is an estimate of when labor may begin; most births occur within a two-week window before or after that date.

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