Understanding SWAPs in Forex: What Are They and Why Do They Matter?

Forex swaps, also known as FX swaps, are a small overnight fee that traders either pay or earn when they hold a position past their broker’s rollover time. These commissions are from the interest rate differentials between the two currencies in the pair you are trading. Swaps matter because they directly influence long-term profitability. In other words, if you are using a strategy that trades overnight, then you need to be aware of what forex swaps are and how they are calculated to avoid paying extra fees. For day traders, these fees make almost no difference, but for swing traders and trend traders, swap costs can add up fast. Understanding how they work can help you avoid unnecessary losses and even earn extra income in some cases.

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What are FX swap charges?

A forex swap is the interest rate adjustment applied to your open trade when it stays active overnight. Every currency has its own interest rate, so when you trade a pair, you automatically deal with an interest rate difference. It won’t bother you unless you leave open trade overnight. 

Because of this interest rate difference, you can earn a swap (positive swap) or pay a swap (negative swap). It all depends on which currency in the pair has the higher interest rate and whether you are buying or selling that currency pair. 

When you trade a pair, you are borrowing one currency and buying another at the same time. If the currency you are buying has a higher interest rate, you may earn a swap. If the currency you are buying has a lower interest rate, you will pay the swap. 

FX swap charges in simple terms 

  • Higher-yielding currency - potential positive swap
  • Lower-yielding currency - likely negative swap

To understand this better, let’s take a look at the EUR/USD example. The U.S. The Federal Reserve has a higher interest rate (around 4% currently) than the European Central Bank (around 2%). This makes saving and investing in U.S. dollars more profitable. So, because the USD rate is higher than the EUR rate, the rule applies. If you are buying the lower-yielding EUR and selling the higher-yielding USD, you have a negative swap rate, and when you sell EUR and buy the dollar, you get a positive swap, therefore earning the interest. In terms of the EUR/USD trade, when you buy EUR/USD, you will have a negative swap, and when you click sell EUR/USD, you will generate a positive swap. Calculating Forex swap becomes much easier when you know these details. 

How FX swaps work

FX swaps are calculated by brokers automatically during the daily rollover. Although the calculation itself looks technical, the idea behind it is relatively simple: swaps reflect the interest rate difference between the two currencies involved. Several factors directly influence the number you see on your platform as swap rates. These factors include central bank interest rates for each currency, overall market liquidity, your position size, and trade direction. Central banks set interest rates for each currency. For example, the Fed sets the interest rates in the USA for the dollar, while the ECB sets rates for the euro in the eurozone. Market liquidity is also important here, as thin markets are risky for traders. Lot size determines the amount of FX swap charges you pay or receive. As a result, you need to know which rate is higher and whether a buy or sell order will bear these rates in your favor. 

Short vs long swap

A long swap applies when you buy the currency pair, while a short swap is applied when you sell it. The swap rate for each direction is different because you are essentially borrowing one currency and lending the other. Let’s discuss a simple example with AUD/JPY. Let’s say you buy the AUD/JPY pair. If the Australian interest rate is higher than the Japanese, then your position may earn a small positive FX swap charge every night. But if the Japanese rate rises or the broker markup changes, that same trade could start costing you money instead. This is why it is crucial to know the difference between short vs long swap concepts to ensure you always know how much you have to pay if you leave the position open overnight. 

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FX swap rates differences between currencies

FX swap charges vary greatly depending on the pair you are trading. These rates are also different from broker to broker. Major pairs usually have smaller, more predictable forex swaps because their interest rate differences are relatively stable. Minor pairs have slightly wider rates, while exotic currency pairs can have very large FX swap charges due to big interest rate gaps and much lower liquidity. 

FX swap rates differences among different currency types:

  • Majors - Lower swap costs
  • Minors - Medium swap rates
  • Exotics - Usually high swap rates

Sometimes, there are triple swaps on Wednesdays, which compensate for the weekend rollover. If you are holding long-term swing trades, Wednesday becomes an important day to watch closely. Exotic pairs like USD/TRY and USD/ZAR can produce extremely high swaps, sometimes positive, and often negative, so they should be traded very carefully when you leave positions open overnight. 

Short vs long swap

A short swap applies when you short the pair, and a long swap applies when you buy a long currency pair. Because each direction has its own interest rate impact, the difference can be large, even for the same pair on the same day. 

This is where carry trading comes into play. Traders who focus on earning positive swaps will choose pairs where they can collect daily interest by holding the higher-yielding currency. 

However, carry trading works when the market goes in their favor; otherwise, losses from price movements can wipe out the swap profits. 

Calculating Forex swap

While each broker uses slightly different formulas, most swap calculations follow a simple pattern. The simplified formula is as follows:

Swap = (Contract Size × Swap Rate × Days Held) / 10

Main variables:

  • Contract size - Lot size (1 standard lot = 100,000 units of a currency)
  • Swap rate - The broker’s daily long or short rate
  • Day held - number of rollovers
  • Direction - Long or short

Swaps usually are small amounts depending on the lot size, but when you hold open trades for 15-30 days, it can make a big difference, especially if you have several positions opened at once. 

FX swap rates play a crucial role in swing trading and trend trading, and it is necessary to monitor them when you deploy systems that are expected to stay in open positions for several days. Forex swap rates change frequently depending on the macroeconomic factors mentioned above, requiring traders to check them daily, unless you are trading on an Islamic account. 

FX swap rates - Islamic accounts

Sharia laws prohibit interest rates in trading and financial transactions. As a result, swap rates can not be applied to traders who need commission-free trading. As a result, there is a dedicated account type that does not charge swap rates. These account types are called Islamic accounts, and they usually come with slightly higher spreads to make up for the 0 swap fees they provide to Sharia law followers. Traders who apply for Islamic traders can use trend trading and swing trading strategies without any extra costs because of FX swap rates, which is a huge advantage. 

Forex swap trading strategies 

The most popular swap trading method is carry trading, but there are several other strategies built around earning or avoiding overnight interest. These strategies are only useful for traders who have an understanding of swap rates, interest rate trends, and the long-term direction of currency pairs. Let’s explain several most popular and viable Forex swap trading systems in more detail. 

Classic carry trading (most popular system)

Carry trading is the foundation of all swap trading approaches. The basic idea is very simple: you buy a higher-yielding currency and sell the lower-yielding one so you can collect daily positive swaps. Popular pairs often include AUD/JPY, NZD/JPY, USD/TRY, and AUD/USD. JPY (Japanese yen) pairs are popular because Japan has lower rates than other currencies, which enables Japanese traders to borrow money very cheaply (near 0%) and invest it in overseas assets. As a result, the pairs mentioned above traditionally offer the largest interest rate differences. Here is how it works: open a position where the long side pays interest. Each night, your swap is added to your account when positive. Pros include consistent daily interest rate generation, high profitability during stable trends, and usefulness in long-term trading. However, the cons are also multiple: price can move against you and erase swap profits, sharp interest rate changes or central bank decisions can reverse trends quickly, and exotic pairs can be volatile and risky. When both fundamental and technical trends support your direction, a carry trade is the best strategy to deploy. 

Trend-following carry trade (swap + trend combination)

Forex swaps can provide additional backwind when you use a trend following strategy, and swap rates are also on your side. This strategy combines swap income with trend trading. Instead of entering a trade solely for positive swap rates, traders wait until the pair is also moving in their favor technically. Here is how it works: identify a currency pair where long swaps are positive, confirm an uptrend using technical tools like moving averages, breakouts, or similar, and hold the position long-term to collect swap earnings while benefiting from the main trend. This strategy is basically an improved version of the carry trading strategy, as it also adds trend trading for huge potential winners. 

Interest rate prediction strategy

This system is based on anticipating central bank interest rate changes, as swap rates often increase or decrease ahead of major policy decisions. In this system, traders follow economic news and central bank announcements. If a country is expected to raise rates, its currency becomes more valuable. Traders usually position themselves to earn future positive swaps and potential price swings. Works best for fundamental traders who are comfortable with macro analysis. 

Swap arbitrage (only for pros)

Swap arbitrage is another forex swap trading system that tries to exploit differences in swap rates between brokers. Swap values usually vary from broker to broker, and sometimes it is possible to open opposing positions across two brokers and collect a net positive. However, this is a very rare occurrence and is not consistent, and some brokers do not allow such practices. So, sticking with other strategies in this guide is a better idea. 

Positive swap grid trading 

If you love grid trading systems, this is the method to go. It combines grid trading with positive swap rates. The only disadvantage here is that grid trading systems are very risky and are only recommended for very experienced traders. This system is simple: traders choose a pair that pays a positive swap on long or short positions. They place multiple grid entries within a price range. The system collects swap on all open positions while also profiting from small price changes. Since it leaves grid positions open overnight, this system is best for slow-moving pairs with a clear long-term trend and small volatility. 

Long-term diversified forex swap trading system

Some traders go as far as to build a portfolio of positions that pay swaps rather than focusing on a single trade. A Forex swap portfolio simply means you can include several traders like AUD/JPY long, NZD/JPY long, and USD/MXN short. This way, traders are able to spread risks across several interest-bearing pairs and stabilize returns. If one pair fails to perform, others will make up for it, which makes this strategy relatively safe. However, it requires a trader to understand several pair fundamentals and calculate several pair swaps. 

Low-swap avoidance strategies

Some traders build techniques to avoid negative forex swaps, especially swing traders who hold positions for days. For swing traders, negative swaps can increase trading costs, and it is best to avoid these extra costs. If they have to open a trade with negative swap pairs, they might select pairs with the lowest negative swap rates. It is also best to avoid exotic pairs and to exit trades before Wednesday to avoid triple swap costs.

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