If a futures PnL result looks far too small or too large, check whether the calculator expects a coin quantity or a dollar notional. The futures PnL calculator has a size mode: in notional mode it converts dollars into quantity using the entry price, while in quantity mode it treats your input as the number of coins or contracts. The same typed number can therefore describe two very different positions.
Check which size you have
Position quantity tells you how many units you hold, such as 0.2 BTC. Notional is the position's value at a price, such as $10,000. For a simple linear position:
notional = quantity × entry price
quantity = notional ÷ entry price
Leverage determines how much margin supports a given notional. It does not change the quantity-to-notional conversion or multiply the gross PnL a second time. If a $10,000 position is opened with 5× leverage, the approximate initial margin is $2,000, but the position remains $10,000 in notional exposure.
The calculator follows this distinction in its sizeMode input. With sizeMode: "qty", the entered size is used as quantity. Otherwise, the entered size is treated as notional and divided by entry price. It then calculates gross PnL as price change multiplied by quantity, with direction reversed for a short. Fees and funding are applied separately. This page explains that simplified linear calculation; contract multipliers and inverse-contract settlement rules can differ by venue and contract.
Worked example: $10,000 notional versus 0.2 BTC
Suppose BTC is entered at $50,000 and exits at $51,000. The price rises $1,000, or 2%. Assume a long position and no fees or funding so the size effect is easy to see.
If your intended position is $10,000 notional, quantity is:
$10,000 ÷ $50,000 = 0.2 BTC
The gross PnL is:
($51,000 − $50,000) × 0.2 = $200
If you select quantity mode and enter 0.2, the calculator also uses 0.2 BTC and returns $200 gross PnL. If you select notional mode and enter 10,000, it converts that notional into 0.2 BTC and returns the same gross result.
Now imagine entering 0.2 while notional mode is selected. The calculator interprets that as $0.20 of notional, not 0.2 BTC. It converts $0.20 ÷ $50,000 into 0.000004 BTC, so a $1,000 price move produces just $0.004 gross PnL. That tiny result is not a bug; it follows from the selected unit. The opposite mismatch can be costly too: entering 10,000 in quantity mode means ten thousand units, which is an enormous position if the tool treats each unit as one BTC.
The example ignores contract multipliers. For a venue contract where one contract represents a fraction or multiple of a coin, first translate the displayed contract count into the units expected by the calculator. Check the contract specification instead of assuming that “quantity” always means whole coins.
A quick input audit
Before trusting the output, write down the position in both units. If you have 0.2 BTC at a $50,000 entry, your simple linear notional is $10,000. If the exchange shows $10,000 position value and your margin is $2,000, do not enter the margin as the position size. Margin is collateral; notional is exposure.
Then compare the expected PnL for a small price move. A 1% move on $10,000 notional is about $100 gross PnL before fees and funding. If the calculator returns pennies, inspect the size mode and units. If it returns an amount many times larger than $100, check that you did not enter notional as quantity or apply leverage twice.
When reconciling a live position, compare like with like: same entry price, same exit or mark price, same quantity, and the same contract type. A PnL panel may include realized fees, funding, or other account adjustments that a simple gross calculation excludes. The position size calculator can help derive a quantity from a stop distance and risk budget; the leverage calculator relates notional to approximate margin. Neither changes the meaning of the PnL calculator's size input.
Common mistakes
- Typing the margin deposit into a field that expects position notional.
- Entering coin quantity while notional mode is selected, or dollar value while quantity mode is selected.
- Multiplying a notional position by leverage to get PnL after the notional already includes leverage.
- Treating a contract count as whole coins without checking the contract multiplier.
- Comparing gross calculator PnL with an exchange's net figure that includes fees or funding.
- Assuming a linear quantity-times-price calculation applies unchanged to inverse contracts.
FAQ
Is position size the same as notional?
People use “position size” for both quantity and value. Confirm the unit shown by your exchange and the mode selected in the calculator. Quantity is units held; notional is their approximate value at the reference price.
Does leverage increase PnL?
Leverage can let a trader support more notional with less margin. At a fixed quantity and price move, gross PnL comes from the price difference and quantity. Increasing exposure may increase PnL because quantity is larger, not because leverage is multiplied into the PnL formula afterward.
Why does my exchange show a different PnL?
The comparison may use a different mark or exit price, contract multiplier, settlement currency, or realized-versus-unrealized field. Fees and funding can also change net PnL. Match those inputs before comparing outputs.
Can I use the calculator for inverse contracts?
Use it as a basic estimate only if its units and formula match the contract. Inverse contracts can calculate PnL and settle in the underlying coin, so their contract rules may need a different formula.
This guide is for educational purposes only and is not financial advice.