Why do backtest results differ from live strategy performance?

Why do backtest results differ from live strategy performance?

Backtest results in FYERS Automate are based on historical market data and the inputs selected during the test, such as date range, initial capital, and slippage. Live strategy performance may differ because real orders are affected by current market conditions and execution factors.

Backtest should be used to evaluate strategy logic and historical performance. It does not guarantee future returns.

Backtest and live execution

A backtest simulates trades using past data, while live execution happens in real time. Results may vary due to slippage, liquidity, fast price movement, order execution, brokerage, taxes, and other charges.

For example, a strategy may show a positive result in backtest, but live performance can change if orders are executed at different prices or if market conditions are different from the tested period.

What if…

ScenarioSolution
My live return is lower than the backtest returnLive trades may have been affected by slippage, liquidity, charges, or market movement.
The backtest was profitable, but live trades are notHistorical performance does not guarantee future results. Review the strategy logic and risk.
I changed slippage and the result changedThe backtest recalculates performance using the updated slippage percentage.
My live order was not executed as expectedLive execution depends on market conditions and order availability at that time.
Last updated: 13 Jul 2026