Egg Freezing Calculator

Egg freezing (planned oocyte cryopreservation) means collecting mature eggs, freezing them, and thawing them later to try for a pregnancy with IVF. Your chance of a baby from frozen eggs depends mostly on two things: how old you were when the eggs were frozen, and how many mature eggs you froze. This calculator combines those two numbers using published live birth rates.

What the Egg Freezing Calculator Measures

It estimates the chance that your frozen eggs lead to at least one live birth, or at least two or three if you hope for more than one child. It can also work backwards and estimate how many mature eggs would give you a chosen chance. It does not measure ovarian reserve or predict how many eggs a cycle will collect.

The Formula

Chance of at least 1 live birth = 1 minus (1 minus p) to the power of n

p = live birth chance per frozen egg for your age at freezing

n = number of mature eggs frozen

Each egg is treated as its own small chance, the same method used by a counseling model from Brigham and Women's Hospital⁴. For two or three children, the calculator uses the matching binomial formula, which adds up the chances of getting fewer births and subtracts them from 100%.

The per-egg chances come from a US study of eggs that were frozen and later thawed, as reported by the American Society for Reproductive Medicine (ASRM)²:

How This Calculator Computes Your Result

Enter your age when the eggs were (or will be) collected, in whole years from 20 to 40. Then enter the number of mature eggs frozen (1 to 100), or pick a target chance from 50% to 90%, and choose 1, 2 or 3 children. Chances are rounded to the nearest whole percent. Eggs needed is the smallest whole number of eggs that reaches your target, up to 100. Ages 41 and over get no number, because the source study had too few women in that group for a reliable rate².

What Your Result Means

Here is how the chance of at least one live birth changes with egg count and age:

And here is roughly how many mature eggs give a set chance of one live birth:

These figures line up with ASRM's ethics guidance, which says about 25 to 30 frozen eggs are needed at age 38 for a reasonable chance of one child³. Hoping for two or three children raises the count a lot. At 30 to 34, a 70% chance of two births takes about 35 eggs.

Why Age at Freezing Matters Most

Egg quality falls with age, mainly because more eggs carry the wrong number of chromosomes. In the data behind the Brigham model, about 57% of tested embryos from women 35 or younger had a normal chromosome count, compared with 49% at 37 and 13% at 44⁴. A frozen egg does not age in storage, so freezing at 32 and using the eggs at 40 gives the chances of a 32-year-old egg. This is also why the per-egg rate in the tables drops from 7.4% to 5.2% across the age bands².

Age also lowers egg numbers. In the Brigham study, women 35 or younger averaged about 14 mature eggs per retrieval, versus about 7 at 43 and older⁴, so older patients often need more cycles.

Why Different Calculators Give Different Numbers

The Brigham model predicts about a 90% chance of a live birth with 20 eggs at age 35⁴. This calculator gives 74% for the same case. The difference comes from the data. The Brigham model was built from fresh IVF cycles and assumes 95% of eggs survive thawing under age 36, and its authors note it may overestimate success⁴. The rates used here come from 1,283 eggs that were actually frozen and thawed, with an overall egg to baby rate of 6.4%¹. Both approaches agree closely at 37, where each gives about 75% with 20 eggs.