The simple holding calculation
For a position that has not been reduced, a basic estimate is: current value = quantity × reference price; cost basis = quantity × purchase price plus the fees included in your record; estimated unrealized profit or loss = current value − cost basis. Return percentage = profit or loss ÷ cost basis × 100, when cost basis is greater than zero.
This simplified calculation describes a position using the values entered. A portfolio with multiple buys, sells, rewards, transfers or fees may need transaction-level accounting. The result is not a tax calculation or a realized return.
A worked Bitcoin example
Suppose you bought 0.5 BTC at £40,000 per BTC and include £50 in purchase fees. Recorded cost basis is (0.5 × £40,000) + £50 = £20,050. At a £50,000 reference price, estimated value is 0.5 × £50,000 = £25,000. The difference is £4,950, or about 24.69% of the recorded cost basis.
Why the estimate can differ from proceeds
A reference price can differ from the price available when you trade. Spread, execution fees, slippage, taxes and timing are not included unless you explicitly include them. When you sell part of a position, the remaining cost basis depends on the accounting method and applicable rules; the simple whole-position formula is not enough to determine that treatment.
The calculators on this site use prices you enter, do not fetch a live execution quote and are intended for information only.
Common questions
Is this the same as realized profit or tax liability?
No. It is a simple estimate from entered quantities and prices. Realized gain and tax treatment depend on transactions, fees and the rules that apply to you.