Which costs should a trading backtest include?

Consider commissions, spread, slippage, exchange and regulatory fees, financing or borrow costs, and market impact. Relevance depends on the instrument, holding period, order type, and size.

How does TradingView model commission and slippage?

A Pine Script strategy can declare commission settings and slippage in ticks. These are simulation inputs and do not reproduce every live execution condition.

Can spread be added directly to every TradingView strategy?

There is no single spread setting that represents every workflow. Spread can be approximated through price or fee logic, but the implementation must fit the order model and avoid double counting.

How should cost assumptions be stress-tested?

Choose a base estimate and several adverse but plausible levels, then compare net results and risk. Keep all other settings fixed during the comparison.

Backtesting guide

Cost Model Realism Backtesting

Cost model realism backtesting means representing the fees, slippage, spread, financing, fill rules, and turnover that a strategy is likely to face. The model should match the intended market and execution workflow instead of using one optimistic percentage for every trade.

Read the practical guide

Key Takeaways

List every cost channel before deciding how to encode it.
Match commission and fill assumptions to the instrument and order workflow.
Inspect gross and net results because turnover can dominate a small edge.
Stress-test worse cost assumptions instead of relying on one estimate.

Create a cost inventory

Map explicit commissions, bid-ask spread, slippage, exchange and regulatory fees, borrow or financing costs, and market impact. Not every component can be modeled precisely in a bar-based backtest. State which items are included, approximated, or omitted so the net result remains interpretable.

Separate fixed, percentage, per-contract, and time-dependent costs.
Use instrument-specific assumptions when tick size and liquidity differ.
Estimate costs at the expected order size, not an unrelated account size.

Encode TradingView assumptions explicitly

Pine Script strategies can set commission type and value, slippage in ticks, and limit-order fill verification through strategy declaration properties. These inputs affect simulated orders but do not reproduce an order book or guarantee live fills. Spread may need to be represented through price or fee assumptions, depending on the strategy design.

Set commission_type and commission_value to match the fee convention.
Use slippage as an explicit stress input rather than an unrecorded adjustment.
Review backtest_fill_limits_assumption when limit fills drive the result.

Stress-test the net edge

Run a small grid from the base estimate to adverse but plausible costs. Compare net profit, drawdown, trade count, turnover, and profit factor. A strategy that changes sign after a minor cost increase has little historical margin for error. The stress range should be set from execution evidence when available, not from the level the backtest can tolerate.

Test higher slippage during volatile periods or at larger order sizes.
Check whether small gross winners become net losers after costs.
Repeat the test when the broker, venue, instrument, or order type changes.

Direct Pineify workflow

Put explicit cost assumptions into the strategy

Pineify Pine Script AI Coding Agent can help add or revise commission, slippage, and fill assumptions in strategy code. Strategy Optimizer can then compare the result across a declared cost range.

Pine Script AI Coding Agent

Generate or revise Pine Script strategy properties for explicit simulation assumptions.

Edit the strategy

Strategy Optimizer

Compare performance across cost or execution-related input scenarios.

Test cost scenarios

Boundary: Pineify cannot infer a broker fee schedule, predict market impact, or reproduce every live fill. The user must supply defensible execution assumptions.

Primary sources

TradingView Pine Script strategies documentationVerified 2026-08-16
TradingView Pine Script declaration statementsVerified 2026-08-16

Related Resources

Backtest sensitivity analysis Strategy decay Pine Script backtesting Pine Script AI Coding Agent

This page is educational and does not provide investment advice. Backtests are hypothetical, depend on their data and assumptions, and do not guarantee future results. Trading can result in substantial loss.