What this calculator estimates
This tool estimates the overnight financing (also called swap or rollover) you may pay or receive when a forex position is held past the broker’s daily rollover cut-off (often around New York 5 p.m.). The estimate is based on the interest rate differential between the base and quote currencies, your position size, the exchange rate, the day-count convention (360 or 365), and the number of calendar days you hold the trade.
The output is a transparent baseline. Brokers can apply their own swap schedules, markups, and multi-day rollovers for weekends/holidays. Use this page to understand direction and magnitude, then compare it with your broker’s published swap rates.
How to use: How overnight financing works (plain language)
In spot FX, a position is economically similar to borrowing one currency and lending the other. If you go long the pair (buy the base currency), you are effectively earning the base currency rate and paying the quote currency rate. If you go short, the roles reverse. The difference between those rates (after converting from annual to daily) drives whether financing is a credit (positive carry) or a debit (negative carry).
A practical way to think about it: if the currency you are “long” has a higher interest rate than the currency you are “short,” the carry tends to be positive. If the currency you are long has a lower rate, the carry tends to be negative. Real broker swaps can deviate because of funding markets, internal costs, and markups, but the interest differential remains the core intuition.
Inputs (what to enter)
- Trade direction: Long means buy base/sell quote; Short means sell base/buy quote.
- Position size (base units): Notional amount in the base currency (e.g., 100,000 for one standard lot).
- Exchange rate (quote per base): The current spot rate for the pair (e.g., 1.0850 for EUR/USD).
- Base and quote annual interest rates: Annualized rates in percent. Negative rates are allowed.
- Holding period: Calendar days held. This calculator spreads financing evenly across days.
- Contract multiplier: Scales the notional (useful for mini/micro lots or partial lots).
- Day-count convention: 360 (bank) or 365 (actual/365) to convert annual rates to daily rates.
- Account currency interest rate (optional): Used here as an opportunity yield on the quote-currency financing amount for the same day-count basis.
Formula used (and sign convention)
The calculator converts annual rates to daily rates and applies them to your adjusted notional. Let: N = position size in base units, M = contract multiplier, d = days held, D = 360 or 365.
Daily rates: rb,daily = (baseRate/100) / D, rq,daily = (quoteRate/100) / D.
Net daily rate: net = rb,daily − rq,daily for Long, and net = rq,daily − rb,daily for Short.
Financing in base units: financingBase = (N × M) × net × d. Financing in quote units: financingQuote = financingBase × exchangeRate.
Interpretation: a positive result indicates a credit; a negative result indicates a debit. This is a simplified interest-differential model and does not include broker-specific swap points, spreads, commissions, or triple-swap rules.
Worked example (realistic numbers)
Suppose you are long EUR/USD with a position size of 100,000 EUR (one standard lot), the exchange rate is 1.0850, you hold for 7 days, and you use a 360 day-count. Assume the EUR annual rate is 3.75% and the USD annual rate is 5.25%.
- Daily EUR rate: 0.0375 / 360 ≈ 0.00010417
- Daily USD rate: 0.0525 / 360 ≈ 0.00014583
- Net (long): 0.00010417 − 0.00014583 ≈ −0.00004167
- Financing (base): 100,000 × (−0.00004167) × 7 ≈ −29.17 EUR
- Financing (quote): −29.17 × 1.0850 ≈ −31.64 USD
In this scenario the carry is negative: holding the long position for a week costs roughly €29 (about $32) under these assumptions. If you flip the direction to short with the same rates, the sign flips and the estimate becomes a credit.
Assumptions and limitations
- Calendar-day model: financing is spread evenly by day; it does not model triple-swap days or holiday calendars.
- Rate inputs are simplified: brokers may use tom-next rates, internal funding costs, and markups.
- No transaction costs: spreads, commissions, and slippage are not included.
- Currency labeling: results are shown in “base units” and “quote units” because the calculator does not know the actual currency codes for your pair.
- Opportunity yield: the “account currency rate” line is an optional add-on and is not a broker swap; treat it as a rough time-value-of-money adjustment.
Practical tips
Use the daily rollover estimate to sanity-check whether financing is material for your strategy. If the daily debit is large relative to your expected daily price move, consider reducing size (via the contract multiplier), shortening the holding period, or choosing a pair/direction with more favorable carry. If the estimate is a credit, treat it as a buffer—not guaranteed profit—because price risk can dominate carry.
Common questions traders ask before holding overnight
Overnight financing is often overlooked because it is small on a single day, but it can compound into a meaningful number over weeks or months. The questions below help you interpret the calculator output in a way that matches how swaps are experienced in real trading accounts.
1) What does “base” and “quote” mean for financing?
A currency pair is written as BASE/QUOTE. For EUR/USD, EUR is the base and USD is the quote. A notional of 100,000 means 100,000 units of the base currency. The exchange rate tells you how many quote units equal one base unit. This calculator reports financing in both base units and quote units so you can see the effect before and after conversion.
Introduction: 2) Why can the sign be different from my broker statement?
Brokers may publish swap as points per lot, as a cash amount, or as a rate. They may also apply a markup, use different reference rates, or include platform-specific adjustments. As a result, your broker’s posted swap can be more negative (or less positive) than a pure interest differential. The sign can also appear inverted if your statement uses a different convention (for example, showing “charge” as a positive number). Here, the sign is straightforward: positive equals credit; negative equals debit.
3) How should I handle weekends and “triple swap” days?
Many brokers apply multiple days of financing on a particular weekday to account for weekend settlement conventions. This calculator does not attempt to guess which day is multiplied; instead, it spreads the total evenly across the number of calendar days you enter. If you want a rough approximation of a week that includes a weekend, enter the full calendar days you expect to hold. If you want to mimic a triple-swap event, you can temporarily increase the days held to see the sensitivity.
4) What if my account currency is neither the base nor the quote?
In many accounts, profits and financing are ultimately converted into your account currency. This page does not perform that final conversion because it does not know your account currency or the relevant conversion rate. The optional account currency interest rate input is therefore treated only as an opportunity-yield adjustment applied to the quote-unit financing amount. If you need a precise account-currency result, use your broker’s conversion rules and the appropriate cross rate.
5) When is financing “material” enough to care about?
A simple rule of thumb is to compare the daily quote-unit financing to your typical daily price movement or to your stop distance. For example, if your expected daily move is 0.3% and your financing is 0.02% per day, it may be secondary. If financing is 0.10% per day and you plan to hold for 30 days, it can become a major driver of net performance. Carry strategies intentionally seek positive financing, but they still face drawdowns when exchange rates move against them.
More context: what can make your broker swap differ
Your broker’s actual swap can differ from this estimate for several reasons. Many brokers use tom-next (tomorrow/next) funding rates rather than policy rates, and they may add a markup. Some apply a multi-day rollover on a specific weekday to account for weekends, and holiday schedules can shift the number of days charged. In addition, some platforms quote swap as “points” or “pips” per lot rather than as an interest-rate differential.
This calculator is still useful because it helps you answer the key planning questions: is the carry likely positive or negative, how sensitive is it to holding period and size, and is it large enough to matter for your expected price move?
If you want to stress-test a trade idea, try changing one input at a time: double the days held to see how quickly financing accumulates; change the day-count from 360 to 365 to see the effect of convention; or adjust the contract multiplier to match your lot size. These quick checks can prevent surprises when you hold a position through multiple rollovers.
Related tools: currency exchange fee comparison calculator (conversion costs) and interest rate parity calculator (forward points vs. rate differentials).
Safety and interpretation notes
This page provides an educational estimate, not a broker quote. Financing is only one component of trading performance. Even if the calculator shows a positive carry, the exchange rate can move against you and produce losses that exceed the financing credit. Likewise, a negative carry does not automatically make a trade “bad” if your expected price move is large enough to compensate.
Finally, be aware that some brokers change swap rates frequently, especially around central bank decisions, quarter-end funding pressures, or periods of market stress. If you plan to hold a position for a long time, consider checking your broker’s swap schedule periodically and re-running the estimate with updated rates.
Arcade Mini-Game: Forex Overnight Financing Cost Calculator Calibration Run
Use this quick arcade run to practice separating useful scenario inputs from common planning mistakes before you rely on the calculator output.
Start the game, then use your pointer or arrow keys to catch useful inputs and avoid bad assumptions.