Most traders obsess over entries, exits and indicators, and treat costs as a rounding error. A few rupees of brokerage here, a fraction of a point of spread there — none of it feels like it matters. And on any single trade, it doesn't. The damage is structural, not per-trade. It only shows up when you stop looking at one fill and start looking at a year of them.
Your true cost has more parts than the line on your contract note. Commission is the obvious one. But there's also the spread — the gap between bid and ask you pay every time you cross it — and, if you hold leveraged or FX positions overnight, swap and funding fees that accrue silently while you sleep. Together they form a tax that's levied on activity, not on profit. The market charges you whether you were right or wrong.
Measure cost against your gross profit, not in isolation
The single most useful reframe is this: a cost number means nothing on its own. "I pay ₹40 a round-trip" tells you nothing. What matters is cost as a percentage of your gross profit — what your strategy earns before the broker takes their cut.
A trader who makes ₹500 of gross edge per trade and pays ₹40 in costs is giving up 8% of their edge. Annoying, survivable. A trader who scrapes ₹60 of gross edge per trade and pays the same ₹40 is handing back two-thirds of everything they earn — and is one bad week away from negative. Same fee. Completely different verdict. The absolute number hid that; the ratio exposed it.
A worked example: break-even on price, negative on costs
Consider a trader who, on raw price action, is almost exactly break-even. Their entries and exits net out to a small gross profit over the year — say ₹30,000 across 800 round-trip trades. On price alone, they have a faint, fragile edge.
- Gross P&L on price: +₹30,000
- Cost per round-trip (commission + spread): ₹50
- Total cost: 800 × ₹50 = −₹40,000
- Net result: ₹30,000 − ₹40,000 = −₹10,000
On the chart this looks like a flat, slightly positive year. In the account it's a clear loss. Nothing about the strategy needs to be "fixed" — the entries were fine. The leak was entirely in the cost line, multiplied by a trade count nobody was watching. (These figures are illustrative; the point is the structure, not the specific numbers.)
Why frequency is the multiplier
Cost is per-trade, so cost drag scales directly with how often you trade. This is why scalping and high-frequency styles are the most fee-sensitive in existence — a tiny per-trade cost, applied hundreds or thousands of times, becomes the dominant term in the equation. The faster you trade, the larger a share of your gross edge the broker silently claims.
Every marginal, low-conviction trade you skip is money saved twice: once because you avoided a likely loss, and again because you never paid the fee to take it.
That second saving is the one nobody counts, and it's why discipline around trade selection pays even when the trade you skipped would have won. It connects directly to overtrading: the cost of churn isn't just the bad fills, it's the toll booth you pass through on every single one. Different styles wear this tax very differently, which is part of what makes some styles quietly profitable and others not.
Know My Trade measures how much of your gross profit is eaten by commission, swap and funding fees, breaks it down by style, asset class and fee type, and reports your cost per round-trip. Crucially, it flags any style where fees exceed profit — so you can see at a glance which corners of your book are working for the broker instead of for you.
What to do about it
The fixes are unglamorous and effective:
- Trade less, but better. Cutting trade count is the most reliable way to cut cost, and it usually improves the quality of the trades that remain.
- Build cost into the bar. Before taking a setup, ask whether the expected move clears your round-trip cost with room to spare. If the edge is thin and the cost is fixed, the setup doesn't qualify — no matter how clean the chart looks.
- Watch overnight holds. For FX and leveraged positions, swap and funding accrue every night you stay in. A position that's flat on price can bleed steadily through financing alone, so factor the holding cost into any multi-day thesis.
None of this requires a better strategy. It requires seeing the tax. Pull your gross P&L, pull your total costs, and put one over the other. If fees are eating a small slice, protect what works. If they're eating most of it — or exceeding profit in a particular style — you've found a leak that no new indicator will ever close.