Forex Swap Calculator

A forex swap calculator tells you how much interest you will pay or earn for holding a currency position open overnight, before you ever place the trade. In foreign exchange (the market where you trade one currency against another), every position left open past the daily rollover time is either charged or credited a small amount called the swap, also known as rollover. The calculator above turns three simple numbers, the swap per lot per night, the number of lots, and the nights you plan to hold, into a clear total cost or credit. This page explains what swap is, the interest-rate difference that creates it, the triple-swap Wednesday rule, positive versus negative carry, and swap-free accounts, so you can plan multi-day trades with your eyes open. Nothing here is financial advice, and no tool can promise profit. The goal is simple: know your holding cost before you commit.

What a Forex Swap or Rollover Actually Is

When you buy one currency you are effectively borrowing the other. Because the two currencies pay different interest rates set by their central banks, holding the position overnight means you owe interest on the currency you sold and earn interest on the currency you bought. The net of those two amounts is the swap. Your broker settles this once a day at a fixed rollover time, usually 5 p.m. New York time, and either adds a small credit to your account or deducts a small charge. If you open and close within the same trading day and never hold past rollover, no swap applies at all. Swap only ever matters for positions carried overnight, which is exactly why multi-day and longer term traders need to price it in.

The word rollover exists because your position is technically closed and reopened at the new day, rolling it forward to the next settlement date. You do not see this happen, and your entry price does not change. All you see is the swap line on your account. On some platforms swap is quoted in points or pips (the smallest standard price increment), and on others it is quoted directly in your account currency per lot. The calculator above works in account currency per lot, which is the clearest way to think about real cost.

The Interest-Rate Differential Behind Swap

Every currency has a benchmark interest rate set by its central bank. When you hold a currency pair, the swap reflects the gap between those two rates, called the interest-rate differential. If you buy a currency with a high interest rate against one with a low rate, the differential works in your favour and you tend to earn swap. If you buy the low-rate currency against the high-rate one, the differential works against you and you pay swap. Brokers also add their own markup and financing costs, so the swap you actually receive is usually a little worse than the pure rate gap would suggest. Rates change over time as central banks adjust policy, which means a pair that pays positive swap today can turn negative later. Always check your broker's current swap table rather than assuming last month's number still holds.

What the Calculator's Inputs and Outputs Mean

The calculator above keeps things deliberately simple so you can run a plan in seconds. Here is each field in plain English.

• Swap per Lot per Night: the amount your broker charges or pays for one standard lot held for one night, in your account currency. Enter it as a negative number if you pay (for example -7.00) and a positive number if you earn (for example 1.50). You find this figure in your broker's swap or specification table.
• Number of Lots: the total position size in standard lots. A standard lot is 100,000 units of the base currency. If you trade mini or micro lots, enter the fraction, for example 0.10 for a mini lot or 0.01 for a micro lot.
• Nights Held: how many overnight rollovers the position will sit through. Count each night the position is open past the broker's rollover time, and remember to count a Wednesday hold as three nights because of triple swap.
• Total Swap (output): the full cost or credit across the whole holding period. Negative means it costs you, positive means it pays you.
• Swap per Night (output): the total divided across the nights, useful for comparing pairs at a glance.
• Direction (output): a plain label telling you whether you pay or earn over the period.
• Nights (output): the night count the tool used, so you can confirm you included any triple-swap adjustment.

How to Use the Forex Swap Calculator Step by Step

1. Open your broker's swap table and find the pair you plan to trade, noting the long (buy) or short (sell) swap depending on your direction.
2. Enter that figure in Swap per Lot per Night, keeping the minus sign if it is a charge.
3. Enter your position size in Number of Lots, using decimals for mini or micro lots.
4. Work out how many nights you will hold, then add extra nights for any Wednesday the position spans (one Wednesday equals three nights).
5. Type that adjusted number into Nights Held.
6. Read the Total Swap and Swap per Night outputs, and check the Direction label so you know if you pay or earn.
7. Compare that cost against your expected move. If overnight swap eats a meaningful slice of your target, rethink the size or the holding period.

The Formula and Mechanics

The maths is refreshingly plain. Total swap equals the swap per lot per night, multiplied by the number of lots, multiplied by the nights held. In short form: Total Swap = Swap per Lot per Night x Lots x Nights. Swap per night is simply the total divided by the nights. The only piece that trips people up is the night count, because of the weekend settlement convention explained below. Keep the sign consistent: a negative swap per lot produces a negative total, meaning money leaves your account. The tool does not model changing swap rates over the period, so if you expect to hold across a central-bank decision that may move rates, treat the result as an estimate and re-run it once rates settle.

Three Worked Examples

Example 1: A Negative-Carry Swing Trade

You go long two standard lots of a pair whose long swap is -7.00 per lot per night, and you expect to hold for five nights with no Wednesday in the window. Total swap is -7.00 x 2 x 5, which equals -70.00. Swap per night is -14.00. The Direction output reads You pay. So before commissions or spread, this position costs 70 dollars just to stay open for the week. If your profit target is only 120 dollars, swap is already draining more than half of it, a clear signal to size down or shorten the hold.

Example 2: A Positive-Carry Hold

You go long three standard lots of a pair whose long swap is +1.50 per lot per night, planning to hold ten nights. Total swap is 1.50 x 3 x 10, which equals +45.00, and swap per night is +4.50. The Direction output reads You earn. Here the overnight interest works in your favour, adding 45 dollars over the period regardless of price direction. This is the mechanic behind carry trades, but never treat the credit as free money: an adverse price move can wipe out many nights of positive swap in minutes.

Example 3: A Hold That Spans Wednesday

You short one standard lot with a short swap of -5.00 per lot per night, opening Monday and closing Friday. The position is open Monday, Tuesday, Wednesday, and Thursday nights, four calendar nights. But Wednesday counts triple, so the effective night count is one plus one plus three plus one, which equals six. Enter 6 in Nights Held. Total swap is -5.00 x 1 x 6, which equals -30.00. Had you naively used four nights, you would have budgeted only 20 dollars and been surprised by the extra 10. This is the single most common swap miscalculation, and the calculator's Nights output helps you catch it.

Swap Scenarios Reference Table

Positive Versus Negative Carry

Positive carry means the pair and direction you hold pay you swap each night. Negative carry means you pay. The same pair can be positive one way and negative the other, because buying the high-rate currency earns while buying the low-rate currency costs. Carry trades try to capture positive carry over weeks or months, but the interest earned is usually small compared with how far price can move. A pair can pay a few dollars a night and still fall enough in a single session to erase a month of carry. Negative carry is not automatically bad either: if your edge is a short, sharp move, a small overnight cost is just part of doing business. The discipline is to always weigh the swap against your realistic price target, which the calculator above makes easy.

Swap-Free and Islamic Accounts

Some brokers offer swap-free accounts, often called Islamic accounts, designed to comply with religious rules that forbid paying or receiving interest. On these accounts the nightly interest swap is removed. That does not always mean holding is free. Many brokers replace swap with a flat administration fee per lot after a certain number of nights, or restrict which pairs qualify. If you use a swap-free account, set the Swap per Lot per Night field to the admin fee your broker actually charges, or to zero only if you have confirmed there is genuinely no holding cost. Read the account terms carefully, because the details vary a lot between brokers.

Practical Tips for Managing Swap

• Check the swap table for your exact pair and direction before entering, since long and short swaps differ.
• Recount nights whenever a hold spans Wednesday, and add the two extra nights for triple swap.
• Re-run the estimate if you plan to hold across a central-bank rate decision, because swap rates can shift.
• Compare swap per night across candidate pairs when the setups look similar; the cheaper hold has an edge.
• For carry trades, never size the position on the swap credit alone; size it on how much you can lose if price turns.
• Log the swap you actually paid after closing, so your journal reflects true net cost, not just entry and exit.

Common Mistakes to Avoid

The most frequent error is forgetting the triple-swap night, which quietly understates the cost of any trade held over the mid-week rollover. A close second is dropping the minus sign, which flips a charge into an imagined credit and makes a losing hold look free. Traders also assume swap is fixed, when in reality brokers update their tables as rates change. Another trap is ignoring swap entirely on small positions, then holding for weeks until the nightly trickle becomes a real dent. Finally, some traders chase positive carry without respecting position size, holding oversized lots for a few dollars of nightly interest while exposing themselves to large price risk. Every one of these mistakes is avoidable by running the numbers before the trade and recording them after.

How Swap Fits Your Trading Journal and Routine

Discipline in trading is mostly about knowing your costs and sticking to a process, not predicting the market. Swap is a real, recurring cost that too many traders leave out of their plan and their review. Build it into your routine: estimate the total swap with the calculator above before you enter, write that estimate into your trade plan, and after the trade closes record the swap you were actually charged. Over a month you will see whether overnight costs are quietly eroding your results and whether your longer holds are truly worth it. A journal that captures swap alongside entry, exit, size, and reasoning gives you an honest picture of net performance rather than a flattering one. That honesty is the whole point of trading with a process.

Swap is one of those quiet costs that separates traders who plan from traders who guess. Use the calculator above to price your overnight holds before you commit, count your nights honestly including any Wednesday triple, and then record the real swap once the trade closes. When you log every trade with its true costs on OneTradeJournal, you build the kind of honest, repeatable process that keeps your decisions grounded in numbers rather than hope.