Forex Swap Calculator
Calculate overnight swap or rollover charges on a position held over days.
Please note: Forex trading carries a high risk of loss, amplified by leverage. Exchange rates must be entered manually — no live market data is used.
What the Forex Swap Calculator does
Swap, or rollover, is the interest adjustment applied when a forex position is held past the daily cut-off. It comes from the interest rate differential between the two currencies in the pair, adjusted by your broker's markup.
Formula
Swap = Rate per lot × Lots × NightsTriple-swap days count as three nights each
Inputs explained
| Input | Unit | Required | Notes |
|---|---|---|---|
| Trade size (lots) | number | Yes | Accepts more than 0. |
| Lot type | one of 4 options | Yes | — |
| Swap rate per standard lot per night | number | Yes | From your broker, quoted per standard lot. Negative means you pay, positive means you earn. |
| Nights held | number | Yes | Accepts 0 or more. |
| Triple-swap days included | number | Optional | Usually Wednesday, charged 3×. Accepts 0 or more. |
| Currency | one of 10 options | Optional | — |
How to use it
- Choose Lot type and Currency.
- Enter Trade size (lots), Swap rate per standard lot per night and Nights held.
- Optionally add Triple-swap days included.
- Select Calculate.
Worked example
Holding 1 lot with a −$4.20 nightly swap for 5 nights including one Wednesday.
- Lots
- 1
- Swap rate
- -4.20
- Nights
- 5
- Triple days
- 1
5 + 2 = 7 effective nights × −$4.20 = −$29.40 paid.
Reading the result
- "Annualised at this rate" is a hypothetical extrapolation of today's rate held for a full year — swap rates float with central-bank differentials, so read it as illustrating scale, not forecasting a year-long cost.
- The progression from "per night" to "30 nights" to "annualised" shows how swap compounds simply through holding time — a small nightly figure becomes material only for genuinely long holds, which is why swap matters far more for carry-style trades than short-term ones.
Assumptions and limitations
- The swap rate is a single flat figure entered for the whole holding period — real broker swap rates move with rate differentials and broker policy, so a rate checked once may not still be current for a long hold.
- Triple-swap day is a number you supply, not something inferred from an actual calendar — the calculator has no concept of which night falls on which weekday, so it relies on correctly counting the broker's designated day within the period.
Common mistakes
- Assuming swap works identically for a long and short position on the same pair — the sign flips with direction, so a rate that pays on one side charges on the other.
- Forgetting to include a triple-swap day when it falls inside the holding period, which understates the true cost of a multi-day hold that crosses the broker's chosen day.
Frequently asked questions
Can swap ever be positive?
Yes, when you hold the higher-yielding currency and the differential exceeds the broker markup. This is the basis of the carry trade, though it exposes you to currency risk.
How do I avoid swap entirely?
Close positions before the daily rollover, or use a swap-free account if your broker offers one.