Home / Calculators / Embryology / Embryo grading explained
Every calculator in one place, free and with no sign-up. Results show instantly — we don't hide them behind a form. Each one explains what the number means, where the reference ranges come from, and what it cannot tell you.
A calculator sees three or four figures. A specialist sees your history, your scans, your partner's results, and how you actually responded to treatment. If you're between cycles, changing clinics, or something in your results doesn't add up, a second opinion is the fastest way to find out whether anything would be done differently.
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These tools provide general information and are not a diagnosis or a substitute for assessment by a qualified clinician. Reference ranges and sources are stated on each calculator. Predictive estimates describe groups of people and cannot predict an individual outcome.
A calculator sees three or four figures. A specialist sees your history, your scans, your partner's results, and how you actually responded to treatment. If you're between cycles, changing clinics, or something in your results doesn't add up, a second opinion is the fastest way to find out whether anything would be done differently.
Free first consultation. No obligation to start treatment, and it doesn't affect your care at your current clinic.
What Gardner grades like 4AA actually describe.
Population estimateAn average for people with your inputs, not a prediction for you. Individual outcomes vary widely around it.
Gardner grading gives a blastocyst a number for expansion and two letters for inner cell mass and trophectoderm quality, as in 4AA. Grade correlates with implantation but does not indicate whether an embryo is chromosomally normal.
Source — Gardner grading: a number for expansion (1–6) then two letters for inner cell mass and trophectoderm quality (A best, C poorest). Grading is subjective and varies between embryologists.
The bands on this page are drawn from published sources but have not yet been reviewed by our medical team, and some vary by laboratory or assay. Check against the reference range printed on your own report.
The number in 4AA
First letter
Second letter
That falls in the Higher band.
Your result of 100 / 100 sits in the highlighted band. Bands are reference points used alongside clinical findings — not a diagnosis.
A well-graded blastocyst. Grading is a visual assessment though, and a good grade does not confirm the embryo is chromosomally normal.
Gardner grading: a number for expansion (1–6) then two letters for inner cell mass and trophectoderm quality (A best, C poorest). Grading is subjective and varies between embryologists.
Highlighted is the stage this measurement belongs to. It is a map of the process, not a schedule — timings vary by protocol and by clinic.
No. Grading correlates with implantation but predicts it imperfectly. Lower-graded embryos produce healthy babies routinely, and units transfer them all the time.
No. Grading is a visual assessment of appearance. Euploid embryos can look poor and aneuploid embryos can look excellent — only genetic testing answers that question.
Inner cell mass is generally weighted more heavily, since it becomes the fetus. Trophectoderm grade has also been associated with implantation, and units differ in how they weigh them.
A calculator sees three or four figures. A specialist sees your history, your scans, your partner's results, and how you actually responded to treatment. If you're between cycles, changing clinics, or something in your results doesn't add up, a second opinion is the fastest way to find out whether anything would be done differently.
Free first consultation. No obligation to start treatment, and it doesn't affect your care at your current clinic.
Grading is subjective and varies between embryologists and laboratories. Nothing here is a diagnosis or a substitute for assessment by a clinician.
A calculator gives you a number. These explain what it means, and what it does not.
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