Supertrend: ATR Bands and State Changes

Calculate the raw bands first

A common construction starts from the midpoint of the bar, (high + low) / 2. It adds and subtracts a multiplier of ATR to form basic upper and lower bands. The final bands can retain earlier values according to conditional rules, and a close crossing the relevant retained band can switch the direction state. TradingView publishes its Supertrend formulas and state conditions.

This distinction matters when recreating an indicator. Plotting midpoint plus or minus ATR creates an envelope, but does not reproduce the carried-band logic. The ATR period, smoothing, multiplier, initialization and equality comparisons all affect the resulting sequence.

A hypothetical state transition

Assume high is 104, low is 100, ATR is 2 and multiplier is 3. Midpoint is 102, so the basic upper band is 108 and basic lower band is 96. Suppose the preceding final upper band was 107 and preceding close was 103. Under the documented upper-band rule, the 108 candidate can be rejected in favor of retaining 107.

If the prior state was downward, price is tested against that retained upper boundary. A completed close of 106 does not cross above 107, so the state remains downward. A later completed close of 108 can flip the state upward, after the band values for that observation have been calculated. The displayed line then follows the applicable lower band rather than remaining at the upper boundary.

This example isolates the state decision; it is not a complete multi-bar backtest. To reproduce every output, a worksheet needs each bar's high, low, close, ATR, basic bands, final bands and previous state. Retaining only the last plotted line loses information necessary to explain the next update.

Understand the signal timestamp

A current bar can cross a boundary and then close back on the other side. A strategy using intrabar observations can therefore act differently from one using confirmed closes. A historical chart generally shows the completed state, so its apparent sequence may not represent every event that was visible in real time.

Price gaps also separate an indicator's threshold from an executable order price. If a line is at 107 but the first available market quote is 110, the chart does not create liquidity at 107. A Supertrend value used as a stop reference remains subject to order type, tick grid and actual execution.

Inspect behavior before choosing parameters

A smaller multiplier can switch state more often; a larger one can delay recognition of a reversal. Neither change proves that overall results improve. Range-bound data may produce repeated state changes, while a long trend can make a heavily delayed setting look appealing in retrospect.

Check ATR construction and valid order increments. Use a documented backtest to record the exact implementation, decision time and costs. The useful output is an auditable state sequence, not a promise that each color change identifies a profitable trade.