How is forex swap calculated?

Approximately notional × (interest-rate differential between the two currencies) ÷ 360, charged per night a position is held. A long position earns the base-currency rate and pays the quote-currency rate.

Do you earn or pay swap?

You earn swap when the currency you are long has the higher interest rate, and pay it when it is lower. Going short flips the sign.

Why is swap tripled on Wednesdays?

Spot FX settles two business days forward, so the Wednesday rollover covers the weekend. Brokers therefore charge roughly three days of swap at once.

Swap / Rollover Calculator

Estimated overnight financing from interest-rate differential. Educational — your broker's actual swap will differ.

Long 1 standard lot of EUR/USD with a +0.50% rate differential earns ≈ $1.58 per night on a USD account (illustrative 4.5% base vs 4.0% quote rate): a 100,000 EUR notional is ≈ $113,989.99 at today's ECB rate, × 0.50% ÷ 360. Going short flips the sign — you pay it. Brokers add a markup and triple-charge on Wednesdays, so treat this as a floor estimate.As of Jul 2, 2026 · ECB reference rates via frankfurter.dev

Rate differential

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Per-day swap (in quote ccy)

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Total swap (in account ccy)

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How swap is estimated

Swap (also called rollover) is the financing applied to a position held past the daily close. The textbook approximation:

swap_per_day = notional × (rate_long_ccy − rate_short_ccy) ÷ 360

Going long a pair, you earn interest on the base currency and pay on the quote; going short, the sign flips.

This is an estimate. Real broker swaps include a markup, broker-specific funding rates, and sometimes triple-swap on Wednesdays (covering the weekend). Always check your broker's swap table before holding overnight.

Useful reference rates: USD ≈ Fed Funds, EUR ≈ ESTR, GBP ≈ SONIA, JPY ≈ TONA.