Your fertile window — and how long it really takes.

For something so central to being human, conception is taught to almost no one. Most of us absorb a vague sense that you have sex and, at some point, a baby happens. When it doesn't happen instantly, that vagueness turns into worry. So here's the clear version — how the fertile window actually works, how to find yours, and how long is genuinely normal before it's worth asking for help.

The biology, plainly. Two simple facts drive everything. An egg, once released, survives only about 12 to 24 hours. Sperm can survive inside the body for up to five days. Put those together and you get the fertile window: roughly six days each cycle — the five days leading up to ovulation, plus ovulation day itself. Outside that window, the chance of conceiving is very close to zero, because there's simply no egg and sperm present at the same time.