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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.
Embryos progressing through the cleavage stage.
Exact calculationArithmetic on the numbers you enter. If your inputs are right, this figure is right.
Cleavage rate is the proportion of fertilised embryos still dividing normally by day 3. Most units expect above 85%, because meaningful attrition usually appears later, between day 3 and the blastocyst stage.
Source — Most units expect the large majority of normally fertilised embryos to cleave. Meaningful attrition usually appears later, between day 3 and blastocyst.
Dividing normally on day 3
Fertilised on day 1
That falls in the 85%+ band.
Your result of 86 % sits in the highlighted band. Bands are reference points used alongside clinical findings — not a diagnosis.
Most fertilised embryos progressing normally, which is what is typically expected at this stage.
Most units expect the large majority of normally fertilised embryos to cleave. Meaningful attrition usually appears later, between day 3 and blastocyst.
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.
Only partly. Most embryos cleave; the informative attrition happens between day 3 and day 5. A good cleavage rate does not guarantee blastocysts.
If very few embryos are available, some units transfer earlier rather than risk none surviving to day 5. It is a genuine clinical judgement — ask what your unit would do and why.
Embryonic genome activation happens around day 3 — before that the embryo runs largely on maternal machinery. Arrest between day 3 and day 5 is where intrinsic embryo problems typically show, which is why the drop-off happens there and not earlier.
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.
Cleavage rate is a weaker quality signal than blastocyst conversion. 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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