Round-trip cost bundles every real cost of completing a trade, the exchange fee on the entry, the exchange fee on the exit, and the slippage incurred on each, into one honest number, usually expressed in basis points (bps; 100 bps equals 1%). It's the true hurdle a trade's expected move has to clear before the trade is worth taking at all.
A strategy that "wins" on 55% of trades but only captures moves smaller than its round-trip cost isn't actually profitable. It's donating the difference to the exchange on every single trade, win or lose. This is why cost-aware backtesting matters more than raw win rate: a strategy needs edge net of round-trip cost, not just a directionally-correct signal.
zengtrade applies a single global round-trip cost figure (currently 15bps for crypto spot) uniformly across every backtest, every strategy, and every forward paper fill, the same honest number everywhere, not a favorable number for the marketing page and a different one for the actual engine.
Educational content, not investment advice. zengtrade is paper-first and non-custodial.