A 50% fall needs a 100% gain to get back — that asymmetry is the whole point of this tool. Enter your portfolio value and equity allocation, pick a historic crash (or set your own), and see the morning-after number: the paper loss, the gain required to recover, and roughly how long that takes at a chosen return. Everything runs in your browser; nothing is uploaded.
Your portfolio & the shock
Assumes the non-equity portion holds its value during the fall (real bonds/cash can also move) and a smooth recovery at the chosen rate. Historic falls are rounded, price-only and USD-based — GBP investors experienced different numbers after FX. Mathematical context only — not investment advice or a prediction. Capital at risk.
Why losses hurt more than gains help
Percentages are not symmetric: what you lose and what you need back are different numbers. Lose 20% and you need 25% to break even. Lose half and you need to double. The deeper the fall, the faster the required recovery grows — which is why the table below is worth memorising before the next drawdown, not during it.
| Equity fall | Gain needed to recover | At ~7%/yr, roughly |
|---|---|---|
| −20% (typical correction) | +25% | ~3.3 years |
| −34% (COVID crash, 2020) | +52% | ~6.2 years |
| −49% (dot-com, 2000–02) | +96% | ~10 years |
| −57% (financial crisis, 2007–09) | +133% | ~12.5 years |
Recovery times assume a smooth constant return — real recoveries are anything but. The 2020 rebound took months; 2000–02 took most of a decade.
What your allocation actually does in a crash
The fall that matters is the portfolio-level one, and your equity allocation sets it. An 80% equity portfolio in a −34% equity crash falls about 27% overall; at 50% equities, the same crash costs about 17%. That cushion is the honest case for holding anything other than equities — not higher returns, but a shallower hole and a shorter climb out. The simulator assumes the non-equity part holds its value, which is kind: in 2022, bonds fell alongside stocks.
How to use the result
The useful question isn’t “will a crash happen” — it’s “could I sit through this number without selling”. Look at the morning-after value with your real numbers in. If the answer is no, the time to change allocation is now, in calm — not mid-fall, where selling converts a paper loss into a permanent one. A monthly ritual helps here: our free portfolio review checklist includes a concentration and allocation-drift check, and our guide to tracking your investment portfolio covers the system around it.
About this tool
- All computation happens locally in your browser using JavaScript — no data is uploaded, stored or sent anywhere.
- Historic falls are rounded S&P 500 peak-to-trough declines, price-only and USD-based — GBP investors experienced different numbers after currency effects. The simulator provides mathematical context only, not a prediction or investment advice. Capital at risk.
Because the recovery is measured from the lower base. £100,000 falling 50% leaves £50,000 — and £50,000 must double to reach £100,000 again. The formula: required gain = 1 ÷ (1 − fall) − 1, which grows much faster than the fall itself.
No — they are rounded, price-only S&P 500 peak-to-trough falls in USD, used as reference points. UK investors in global funds experienced different portfolio-level numbers, and currency moves can soften or deepen a fall in GBP terms.
It shallows the fall: only the equity portion takes the modelled hit, so 50% in equities roughly halves the portfolio-level drawdown versus 100%. The simulator assumes the non-equity part holds steady — kind but not guaranteed, as 2022 showed when bonds fell alongside stocks.
Yes — the simulator runs entirely in your browser. Nothing you type is uploaded, stored, or sent to any server.