Trading fees and break-even calculator
“Before this trade makes a cent, how far does price have to move just to pay for itself — and what do these costs add up to over a hundred trades?”
Costs are charged twice and noticed once. This calculator converts commission and slippage into the price move a trade needs to net flat, then multiplies that round trip by a run length so the total is visible in one number rather than a hundred small ones.
Free to use, nothing to sign up for, and nothing you type here is sent anywhere — the arithmetic runs in your browser.
What it computes
commission cost = per-side commission x 2 (per-share mode multiplies by shares first) slippage cost = slippage per share x shares x 2 round trip = commission + slippage break-even move = round trip / shares (in price) break-even % = break-even move / entry x 100 break-even price = entry +/- the move (long / short) fee drag = round trip x trades
What you type in
| Field | What it means | Example |
|---|---|---|
| Entry price | The entry, which the break-even percentage is measured against. | 100 |
| Shares | Quantity, which spreads the round trip across more or fewer units. | 100 |
| Commission | Per side. Flat by default, or per-share with the toggle. | $1 |
| Per-share toggle | Switches the commission unit. | off (flat) |
| Slippage per share | Spread and slippage cost per share, charged on both sides. | $0.01 |
| Trades | The run length for the fee-drag projection. | 100 |
Reading the result
- Round trip — the total cost of opening and closing once.
- Break-even move, in price and in percent, plus the break-even price for a long and a short.
- Fee drag — the same round trip repeated over the run length set in the field.
Worked example
Entry 100, 100 shares, $1 flat per side, $0.01 slippage per share, 100 trades.
- Commission both sides $2, slippage both sides $2, round trip $4
- Break-even move $0.04, i.e. 0.04% — the long needs 100.04 to net flat, the short 99.96
- Cost as a share of the $10,000 position: 0.04%
- Fee drag over 100 trades: $400
$400 is 4% of a $10,000 account, paid in pieces too small to notice one at a time. That total is the reason the projection field exists.
What trips people up
- The commission unit is a real trap. Flat-per-side and per-share differ by the share count — at 100 shares that is a 100x difference in the answer. The toggle is not cosmetic.
- Slippage is charged twice, once on each side, because that is when it happens.
- The break-even figures ignore financing, borrow and taxes.
Questions
- Should commission be flat or per share?
- Whichever your broker charges. Equity brokers commonly quote a per-side total; futures and options are usually per contract per side. Ledger of Alpha stores the two units separately for exactly this reason.
- What slippage number is realistic?
- Your own fills are the only honest source. A liquid large-cap and a thin small-cap are not comparable, and the figure belongs to the instrument and the size, not to the market as a whole.
Related calculators
These are the same calculators built into Ledger of Alpha, where they read your own trade history instead of numbers you re-type. See the full product
Keep the record these numbers come from
A free account logs the trades you size here, so the win rate and averages you type into these calculators come from your own history rather than a guess.