A fall and the rise that undoes it are not the same size. A 50% loss needs a 100% gain just to get back to where you started.
Enter a loss, or the value before and after. The arithmetic runs in your browser; nothing is sent anywhere. It does not tell you what to buy or sell.or
Arithmetic: gain needed = 1 ÷ (1 − loss) − 1; years at a constant rate r = ln(1 ÷ (1 − loss)) ÷ ln(1 + r). Fees, taxes, inflation, deposits and withdrawals are not included, and they change the answer. The checks after a loss are set out, with sources, in After a big investment loss: what to check before you act.
The arithmetic at a glance
| Loss | Gain needed to get back |
|---|---|
| 10% | 11.1% |
| 20% | 25% |
| 30% | 42.9% |
| 40% | 66.7% |
| 50% | 100% |
| 60% | 150% |
| 75% | 300% |
| 90% | 900% |
The gap grows faster than the loss. Going from a 50% loss to a 75% loss makes the fall half as large again, but triples the gain needed, from 100% to 300%. The formula describes the past, not the future: it says nothing about how long a recovery will take, or whether it will happen.
Research on investors after large losses, from panic selling to the urge to win money back, is covered in our investment loss guide and in Why most stock investors lose money.
Before you rely on this
This is a reference, not a verdict. It works from published rules and published research, applied to the handful of things you typed in. Real situations turn on details it never sees — whose name is on what, how a document is worded, which rules apply where you live, the specific facts of your case, and factors nobody has measured yet. A different answer from a professional who can see all of it is the one to trust.
Averages are not predictions. Where a figure here comes from a study, it describes what happened to a group of people on average. It does not say what will happen to you. An average is the right tool for deciding what to change and the wrong tool for deciding what is going to happen.
Nothing here is advice. Not financial, legal, medical, insurance or safety advice, and using this page creates no professional relationship of any kind. The sources are linked so you can check them yourself. For a decision that matters, ask someone who is accountable for the answer.