How many trades is enough?

Trade count gates every other metric

A 70 percent win rate from 10 trades and a 70 percent win rate from 300 trades are not the same claim. The first is seven good trades, easily produced by luck; the second is a pattern. When you optimize, the search will happily hand you the combination with the prettiest metrics, and on a small sample that is usually the luckiest one, not the best one. Filtering by a minimum trade count is how you stop the optimizer from rewarding noise.

The noise floor, in one formula

The uncertainty in an observed win rate shrinks with the square root of the number of trades. The standard error below shows why small samples are so unreliable: at 25 trades a 60 percent win rate carries roughly a 10 point swing in either direction; at 400 trades that swing is about 2.5 points. Four times the trades, half the uncertainty.

from math import sqrt

# Standard error of an observed win rate p over n trades.
def win_rate_se(p, n):
    return sqrt(p * (1 - p) / n)

win_rate_se(0.60, 25)   # 0.098  -> about +/- 10 points
win_rate_se(0.60, 100)  # 0.049
win_rate_se(0.60, 400)  # 0.024  -> about +/- 2.5 points

Working rules of thumb

There is no magic number, but practical thresholds help you avoid the worst mistakes:

• Under 30 trades: treat every metric as anecdote, not evidence.
• 30 to 100 trades: a rough read; fine for discarding obviously bad settings, weak for ranking the good ones.
• 100 to 200 trades: a reasonable sample for most swing strategies.
• 200 or more trades: enough that metric differences start to be real rather than noise.

How to raise the trade count

If a strategy simply does not trade much, you have three honest levers, in order of preference: extend the date range so it sees more history; test on a lower timeframe where signals fire more often, accepting higher relative costs; or broaden the entry condition so it triggers more, at the risk of diluting the edge. What you must not do is keep the tiny sample and pretend the metrics are solid.

//@version=5
strategy("Trade Count Aware", overlay=true)

// ... entries and exits ...

// Show the running count of closed trades on the chart.
var label tag = na
if barstate.islast
    label.delete(tag)
    tag := label.new(bar_index, high,
         text = "Closed trades: " + str.tostring(strategy.closedtrades),
         style = label.style_label_down)