Formula
The formula is displayed so the result can be checked independently. PreBreakout does not use a hidden scoring model on this page.
Worked hypothetical example
For the hypothetical series 100, 120, 110, 90, 130, 80, 125, 140, the deepest decline is from the running peak of 130 to the later trough of 80: 38.46%.
Important: the numbers are fictional and are not associated with a security, issuer or current market price.
What this calculator does not tell you
- Order matters: a trough only counts against a peak that occurred earlier in the series.
- The calculation describes the values you paste; it does not estimate future drawdown or probability.
- Use consistent observations if you compare two series, because different sampling frequencies can produce different maximum drawdowns.
Why a simple high-minus-low calculation is not enough
Maximum drawdown is path-dependent. If a low occurs before a later high, that pair cannot represent a decline from that high. The calculator therefore walks the sequence in order, updates the running peak as new highs appear, and compares every later observation with the highest value seen up to that point.
Sampling frequency changes the observed path
A sequence of daily observations can contain a deeper peak-to-trough move than a monthly sequence covering the same broad period because monthly sampling may skip intermediate extremes. When comparing examples, keep the observation rule consistent.
How to use it for learning
Change one input or observation at a time and check how the output changes. The page reports only deterministic arithmetic from your inputs; it does not convert the result into a quality score, forecast or trading instruction.