Define what you want to break even on
The P&L calculator accepts direction, entry price, exit price, position size in units and one fee rate per side. It returns gross P&L, modeled entry-plus-exit fees, modeled net P&L and return on entry notional. It does not have a button that solves for a break-even price. This guide supplies the algebra; the tool lets you check the resulting scenario.
The assumed rate applies equally to both legs, while each leg uses its own notional. With ten units bought at $100 and sold at $101, the model charges the entry percentage against $1,000 and the exit percentage against $1,010. Using $1,000 for both legs would answer a different question.
Real fee treatment can be more complicated. Coinbase Exchange documents maker/taker pricing and partial fills that can receive different treatment. Coinbase Advanced directs customers to the applicable account rates and notes that some pairs have separate schedules. These examples explain why one assumed rate is a simplification; neither source establishes a rate for the reader. Exchange documentation · Advanced documentation
Evidence: Exchange documentation · Advanced documentation
Solve the long example
Let E be entry price in dollars per unit, X exit price, q positive units, and f the fee rate as a decimal. Entering 0.1 in the tool's percentage field means f = 0.001 in the equations, not 0.1.
For a long, gross P&L is q × (X − E). Modeled fees are q × f × (E + X). Set net P&L to zero:
q × (X − E) − q × f × (E + X) = 0
X × (1 − f) = E × (1 + f)
X = E × (1 + f) / (1 − f)
The last line assumes q > 0 and 0 ≤ f < 1. It is not a formula for rebates, inverse contracts or an exchange's minimum commission. The tool rejects negative fee inputs. At an assumed fee of 100% per side, the long formula has no finite break-even exit for a positive entry; do not divide by zero or interpret a validation boundary as a plausible fee.
Use invented inputs of entry $100, ten units and 0.1% per side. The modeled long break-even exit is $100 × 1.001 / 0.999 = approximately $100.2002002. Enter Long, Entry price 100, Exit price 100.2002002, Position size 10 and Fee rate per side 0.1.
At the unrounded mathematical exit, gross P&L and total fees are each approximately $2.002002, leaving zero net within floating-point tolerance. The needed price increase is approximately 0.2002002%, slightly more than twice the 0.1% input. The difference arises because the exit fee applies to a slightly higher notional.
Check rounding before calling the result zero
All table values use the same fictional entry, units and fee assumption. Dollar figures are shown to enough decimals to expose rounding. The tool allows up to eight decimal places for nonzero dollar amounts below $1, and up to two otherwise.
A displayed zero after rounding is not evidence of exact break-even. In the middle row, the loss is two-tenths of one cent across the ten-unit position; the tool can display this as −$0.002. Much smaller floating-point residuals can still round to zero. A venue's permitted price increments and execution costs are not supplied to this model, so the extra decimal places should not be mistaken for a tradable quote.
Keep the full calculated exit while checking the algebra. Round only when presenting the result, and record whether rounding was applied to the price, each fee or the final net amount. Actual venue rounding rules may differ from this simplified calculation.
| Long exit per unit | Gross P&L | Total fees | Modeled net |
|---|---|---|---|
| $100.00 | $0.000 | $2.000 | −$2.000 |
| $100.20 | $2.000 | $2.002 | −$0.002 |
| $100.21 | $2.100 | $2.0021 | $0.0979 |
Reverse the price direction for a short
For the model's short setting, gross P&L becomes q × (E − X); modeled fees still subtract from the result. Setting net to zero gives:
q × (E − X) − q × f × (E + X) = 0
X = E × (1 − f) / (1 + f)
Using the same invented inputs, the exit is approximately $99.8001998. Gross P&L and fees are each approximately $1.998002 at the unrounded result. Entering $99.80 instead produces about $0.002 positive modeled net. The rounding effect changes sign relative to the $100.20 long example.
This calculation does not establish that a short can be opened or held. It does not include borrowing, funding, collateral or liquidation. Read long and short P&L for direction mechanics and calculator liquidation limits for what the tool cannot determine.
Understand when quantity cancels out
Quantity appears in both gross P&L and the proportional fee term, so it cancels when solving this particular zero-net equation. Doubling units doubles the dollar gain and the modeled fees but leaves the break-even price unchanged. That is a property of the assumptions, not a general statement about transaction costs at different sizes.
A fixed charge would not cancel the same way. For a long with an additional hypothetical fixed round-trip cost C, the extended algebra would be X = [E × (1 + f) + C/q] / (1 − f). This is an explanatory extension only: the current tool has no field for C. Do not silently fold a fixed amount into the single rate and call the output an exact calculation.
Different entry and exit percentages would also require separate terms. The current interface uses one rate, so it cannot directly represent different maker/taker rates on the two legs. Spreads, slippage, funding, borrowing, taxes and network charges can alter an actual economic result. See trading-fee limitations.
Reproduce the workflow
The displayed return uses entry notional as its denominator, not collateral or total account value. Net in this article means net of the tool's two percentage fees only. A near-zero model result does not promise an available fill, an after-tax outcome or a loss limit.
- Choose fictional inputs and state whether the position is long or short.
- Convert the assumed fee percentage to a decimal for the algebra.
- Calculate the hypothetical break-even exit using the appropriate equation.
- Enter the result in the P&L tool with the original percentage input. Inspect gross, fees and net separately.
- Change the exit slightly in each direction. Keep extra decimals in your notes and list excluded costs.
Sources & method
- Exchange documentation
Primary source checked November 4, 2026. Provider statements retain the scope and uncertainty described in the text. Checked 2026-11-04.
- Advanced documentation
Primary source checked November 4, 2026. Provider statements retain the scope and uncertainty described in the text. Checked 2026-11-04.
- CryptoTrades P&L calculator
Formula, fee input and money display checked against the implementation; synthetic examples reproduced. No exchange execution tested. Checked 2026-11-04.
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