Why your win rate lies
A win rate on its own says nothing about whether a strategy has an edge, because it moves for free with where you put your exit. Move the target closer and the win rate goes up — with no change to the market and no change to skill, nothing but geometry.
Take a coin flip with a stop and a target the same distance away, 5% on each side. Random price movement clears the target first about half the time, so a coin gets roughly a 50% win rate. Now keep the same stop but pull the target in to 2.5%. The same coin, still deciding nothing but chance, clears that closer target around 67% of the time. Nothing about the underlying odds changed. Only the finish line moved.
This is why two traders can quote the same win rate and mean opposite things — and why a strategy with a "low" 35% win rate can be the one with real edge, once its risk and reward are taken into account. A win rate needs a baseline before it means anything. That baseline is what this calculator gives you.
How this is calculated
The baseline comes from the geometry of your stop and your target, nothing else. If your stop sits risk% away from entry and your target reward% away, a purely random walk reaches the target first with probability:
p = risk / (risk + reward)
That is the win rate luck alone would produce with your exact levels — not 50%, not a round number, whatever your risk and reward actually work out to. Multiply that probability by the number of trades you closed and you get the number of wins chance alone would expect. Compare that expectation to what you actually got, scale by how much a result like that naturally varies, and you have a z-score: how many standard deviations your real result sits from what randomness alone predicts.
How to read your result
A z-score near 0 means your result looks like something chance could easily produce. A z-score far from 0 means your result would be unusual for chance to produce — evidence, not proof, that something other than luck is driving it.
- Above +2 — real edge Your win rate beats what randomness would produce by more than two standard deviations. That is not proof of a durable edge — no calculator can give you that — but it is a real, unusual result worth taking seriously and worth continuing to track.
- Between −2 and +2 — inconclusive The sample cannot yet tell skill apart from luck. This is the most common answer, and it usually means one thing: keep tracking the same way, with more trades, before drawing a conclusion either way.
- Below −2 — worse than random Worse than random with those same stop and target levels. Worth a hard look at execution — are stops actually held where they are set, are targets actually taken — before concluding the strategy itself is the problem.
Whatever the number says, the next useful step is usually the same: look at the setup and the levels behind it, not just the outcome. Our methodology explains how we build indicators around structure and levels rather than raw win rate, and the full indicator catalog puts those levels to work.
Why averages are not enough
The Quick mode above uses your average stop and average target distance, and for a fast gut-check that is a fine estimate — but only if your trades tend to use similar-sized stops and targets. If they vary a lot from trade to trade, averaging first and computing the z-score second can give you the wrong sign.
We tested this on a real signal set of ours where risk ranged from 0.16% to 30% between trades. Computed trade by trade — each one contributing its own probability from its own levels — the result was z = −2.17: worse than random. Computed from the averages of the same set, it came out z = +0.87: a mild positive. Same trades, opposite conclusion, because the average hid how much the geometry moved around from one trade to the next.
That is what Exact mode is for. Paste one trade per line — entry, stop, target, win or loss — and the calculator computes the probability for every single trade from its own levels before combining them, the same way as above and the same way we run it internally. It takes a minute longer to prepare. If your risk and reward vary trade to trade, it is the only mode that tells you the truth.
