What swap is
When a forex position is held past the daily rollover, it is closed and reopened for the next value date. The interest-rate difference between the two currencies is charged or credited, and that adjustment is the swap.
total swap = rate per lot per night × lots × nights
Two properties make it different from every other cost:
- It accrues with time, not with activity. A position held for three weeks pays twenty-one times.
- It can be positive. Holding the higher-yielding currency of a pair can pay you, which is the mechanism behind carry trades.
The triple-swap day
Forex settles on a two-business-day basis, so the roll on Wednesday covers the weekend and is charged at three times the normal rate. Some brokers use Friday instead, particularly on non-forex instruments.
The practical effect is not subtle. A swing trader who habitually opens on Tuesday and closes on Thursday is paying five nights of swap for two days of exposure, and has probably never noticed. Whether the triple day falls inside your typical hold is worth checking once.
Why the yearly figure is on this page
A rate of −$7.50 per lot per night looks like nothing. It is $225 a month and $2,737 a year on a single standard lot.
That figure is worth comparing against your average trade result rather than against your balance. If the yearly carry on your typical position size approaches your yearly profit, the strategy is competing with its own holding cost — and the fix is usually shorter holds or a different pair, not better entries.
The same logic applies to the crypto version of this cost, which arrives as funding every eight hours instead of nightly.
Where the numbers come from, and why we ask
Swap rates are set by each broker, not by the market. They differ between brokers on the same pair, differ between the long and short side of that pair, and change without notice.
That is why this calculator asks for the rate rather than shipping a table. A table would be wrong for most visitors within weeks, and quietly — which is worse than asking. Your broker publishes current rates in the contract specification, usually inside the platform.
Two related notes: swap-free "Islamic" accounts typically replace it with a fixed administration fee rather than removing the cost, and a few brokers apply swap in points rather than currency, in which case convert before entering it here.