Swap Calculator

A spot FX position that stays open through the daily rollover is charged or credited a day of interest. The long holds the base currency, so it earns the base currency's rate and pays the quote currency's; the short is the reverse. The interest-rate differential approximates the interbank tom-next forward points that set the cost of rolling a position one day forward, and brokers add a markup, so a broker's swap can differ from the estimate, and the markup can make both sides a charge.

In interest-rate mode each leg accrues on its own currency's day count: actual/360 for EUR, USD and CHF, actual/365 for GBP, JPY, AUD and CAD. No verified day count is held for NZD, so the calculator asks for it, and every day count is editable because a broker can apply its own basis. The base leg is in the base currency and converts into the quote currency at the entered price. A markup is entered as one annual total and split half on each leg, coming off the rate earned and added to the rate paid. In swap-points mode the broker's swap long or swap short, in points or pips as the platform publishes it, is multiplied by the size of that unit and by the units, giving the swap in the quote currency; on a 5-digit quote (3-digit for JPY pairs) a point is a tenth of a pip.

Spot FX rolls over once each trading day. The rollover on the triple day, Wednesday by default, carries three days of financing: for the many pairs that settle two business days after the trade, a position rolled on Wednesday moves its value date from Friday to the following Monday. Brokers set the triple day per symbol, so it is editable. Value-date holidays, which can move extra days onto other rollovers, are not modelled.

The cost of holding adds the spread and the commission, half of each at entry and half at exit, with the swap at each rollover in between. The spread is measured against the mid price and paid once per round trip. The swap and the spread convert into the account currency the way the Pip Value Calculator converts a pip value; commission is taken as charged in the account currency.

1 standard lot of EUR/USD long at 1.1253 on a USD account has a notional of 100,000 × 1.1253 = $112,530. With the euro deposit facility rate of 2.50% and the 4.00% upper limit of the US federal funds target range, both on actual/360, and no markup, the euro leg earns €100,000 × 2.50% ÷ 360 = €6.94, or $7.81 at 1.1253, and the dollar leg pays $112,530 × 4.00% ÷ 360 = $12.50: −$4.69 for each day of financing.

Opened on a Monday before the daily rollover and closed the following Monday before it, the position is held through five rollovers, Monday to Friday. Wednesday's carries three days, so the swap covers seven days: 7 × −$4.68875 = −$32.82, with the daily figure unrounded.

With an illustrative 0.2-pip spread and $7.00 round-trip commission per lot (brokers set their own), entry and exit each cost $1.00 of spread and $3.50 of commission, $4.50 apiece. The week costs −$4.50 − $32.82 − $4.50 = −$41.82, 78% of it swap. The short side of the same position is credited $32.82 over the week before any markup; a broker's markup reduces that credit and can turn it into a charge.