If you’re undergoing a Frozen Embryo Transfer (FET), you probably want to know your estimated due date and how far along you are. While traditional pregnancy calculators use the last menstrual period (LMP), that method doesn’t apply to FET cycles. That’s where our FET Pregnancy Calculator comes in.
Designed for simplicity and accuracy, this calculator uses your embryo transfer date and the embryo’s age at transfer to calculate:
- Your estimated due date
- Your current gestational age (in weeks and days)
FET Pregnancy Calculator
🔧 How to Use the FET Pregnancy Calculator (Step-by-Step)
Using the calculator is quick and easy. Follow these steps:
- Enter Your FET Transfer Date
Use the date picker to select the exact date your embryo was transferred. - Input Embryo Age at Transfer
This is the number of days the embryo had developed before transfer. Most commonly, this is 5 days (blastocyst stage), but it could be 3–6 days. - Click “Calculate”
The calculator will instantly show:- Your estimated due date
- Your current gestational age (how far along you are today)
- Click “Reset” if You Want to Start Over
The form will reload, allowing for a new calculation.
✅ Example Use Case: FET Due Date Calculation
Let’s say your embryo transfer was on March 15, and it was a 5-day embryo.
- The tool subtracts 4 days from March 15 (since ovulation is considered the embryo’s fertilization day), resulting in March 11 as your ovulation date.
- Then, it adds 280 days to estimate your due date.
- You’ll get:
- Estimated Due Date: December 16
- Gestational Age Today: For example, 20 weeks 3 days
This makes it much easier to track your pregnancy milestones, appointments, and growth progress.
🧠 Why FET Requires a Special Pregnancy Calculator
Unlike natural conception, where the LMP and ovulation are used to estimate gestational age, FET patients have a controlled transfer and fertilization date. The embryo is already several days old when transferred, and this alters how pregnancy duration is measured.
The FET calculator accounts for:
- The embryo’s age at transfer (1–6 days)
- The fertilization (conception) equivalent date
- The standard 280-day gestational period
This gives you a medically aligned due date and gestational age tailored to assisted reproductive technology (ART) timelines.
📌 Key Features of the FET Pregnancy Calculator
- 🧮 Accurate Results based on embryo transfer data
- ⏱️ Instant Calculation—no delays or waiting
- 📱 Mobile-Friendly design for use on any device
- 👩⚕️ Clinically Useful for both patients and fertility professionals
- 🔁 Reset Button for multiple calculations
🤰 Common Use Cases
- Couples or individuals undergoing IVF with frozen embryo transfers
- Fertility clinics offering patient education and aftercare
- Tracking pregnancy milestones based on ART protocols
- Creating personalized pregnancy plans or announcements
- Calculating gestational age for ultrasounds or prenatal tests
❓ Frequently Asked Questions (FAQs)
1. What is a FET pregnancy calculator?
A FET pregnancy calculator determines your due date and gestational age based on your frozen embryo transfer date and the age of the embryo at the time of transfer.
2. Why can’t I use a regular pregnancy calculator?
Regular calculators use LMP, which doesn’t apply to IVF or FET cycles. You need to base your calculation on the embryo’s development stage and transfer date.
3. How accurate is this calculator?
It’s as accurate as the data you provide. It’s based on medical protocols that calculate pregnancy from the fertilization date plus 280 days.
4. What embryo age should I input?
Use the number of days the embryo had developed before transfer. Common values are 3, 5, or 6 days.
5. What if I don’t know the embryo age?
Contact your fertility clinic. Most blastocysts are 5 days old at the time of transfer, but it’s important to use the correct value for accuracy.
6. Can I calculate twins or multiples with this?
The due date remains the same, but twin/multiple pregnancies often deliver earlier. Always follow up with your OB/GYN.
7. Does it work with donor embryos?
Yes. The calculator only needs the embryo’s development stage and transfer date, regardless of origin.
8. Can I use it for frozen egg transfers?
No. It’s specifically for embryo transfers, not oocyte or egg-only procedures.
9. What if I transferred a 6-day embryo?
Enter “6” in the embryo age field. The calculator will adjust accordingly.
10. Is this tool free to use?
Yes, the calculator is completely free and doesn’t require login or downloads.
11. Does it store my data?
No, the calculator runs entirely in your browser and does not store any personal information.
12. Can I bookmark the result?
Results disappear after refreshing or navigating away. It’s best to note your results separately.
13. What’s the gestational age?
It shows how far along you are in weeks and days, starting from the fertilization equivalent date.
14. Is this calculator suitable for medical use?
It’s a helpful estimation tool, but you should always confirm due dates and gestational age with your doctor.
15. Why is 280 days used for pregnancy?
This is the standard full-term duration from conception to delivery in clinical obstetrics.
16. What if my embryo transfer date is in the future?
You’ll need to wait until after the transfer to use the calculator correctly.
17. Can I calculate using IVF with fresh embryos?
This tool is specifically for FET. Fresh embryo calculators work slightly differently due to ovulation timing.
18. What if I transferred two embryos on different days?
Only use this tool for a single transfer event. Consult your clinic if your case is more complex.
19. Can I use this tool multiple times?
Yes! Just click the “Reset” button to run a new calculation.
20. Will this calculator be updated for newer protocols?
Yes, it’s designed to reflect best practices and will be updated as ART methods evolve.
🧾 Final Thoughts
The FET Pregnancy Calculator is a powerful, simple-to-use tool for those on their fertility journey. Whether you’re an IVF patient or a fertility professional, this tool saves time, reduces guesswork, and provides peace of mind with accurate results.