How rollover is calculated for EUR/NZD

Direct answer

Rollover (often called swap) for EUR/NZD is the net interest effect of holding a forex position overnight. Conceptually, it comes from the interest-rate difference between the euro and the New Zealand dollar, converted into a daily amount, then adjusted by the way your provider applies swap terms (including any special conventions such as triple-swap on certain days).

Mechanism and definition: what rollover tries to represent

In spot forex, you typically enter a trade as an exchange of currencies with settlement conventions. When you keep the position open past the normal settlement timing, the economic exposure shifts from “spot exchange” toward “carry.” Rollover is the provider’s method for charging (or crediting) that carry for each overnight holding period.

A common way to think about it is:

• Choose the two currencies involved (EUR and NZD).
• Use interest-rate inputs for each currency to estimate what holding that currency would “earn” or “cost.”
• Convert those annualized ideas into a daily interest factor using day-count conventions.
• Apply the factor to your position size, separately considering whether you are long or short each currency.
• Combine and then add provider-specific adjustments (for example, how they compute the swap points and how they handle pricing components).

Important: your account’s displayed rollover numbers are not just a mathematical abstraction; they are terms the provider publishes. Market rates and provider methodology can cause differences from generic “interest difference” intuition.

Evidence or example (with explicit assumptions)

Because exact provider formulas vary, a self-check method is usually more reliable than trying to recreate the provider’s internal computation from public rate sheets.

Assume a simplified model to understand the moving parts:

1. Daily rates

• Suppose you have an annual “interest input” for EUR and another for NZD.
• Convert each to a daily rate using a day-count convention (for instance, dividing by 360 or 365—providers and rate sources differ).
• Let the daily EUR factor be r_EUR and the daily NZD factor be r_NZD.

2. Directional effect

• If you are long EUR/NZD, you are effectively exposed to being long EUR and short NZD.
• In a simplified sign convention, net carry is “(EUR benefit) minus (NZD cost).”
• If you are short EUR/NZD, the sign flips.

3. Position size scaling

• Rollover is typically proportional to the notional amount (contract size) and expressed per day or per rollover event.
• Currency conversion may be needed to express the final amount in your account currency.

4. Triple-swap convention On certain rollover days, many providers apply a “triple” multiplier so the charge/credit reflects an extended holding period (for example, when there is an additional non-business day). In practice this means the overnight rollover entry is larger on those days than on normal rollover days.

5. Provider adjustments Even with the same underlying interest inputs, providers may apply additional adjustments when forming the actual swap points (for example, through pricing of the two legs, liquidity/hedging effects, or the way they incorporate their own costs and quoting conventions). That is why two accounts can show different EUR/NZD rollover outcomes.

Material limitation: a simplified example can explain direction and scaling, but it cannot guarantee the same numeric result you will see on your statement. The only dependable way to match the number is to compare your provider’s published swap terms (or the actual posted rollover entries) to your specific position size and direction.

Limitations and risks (what can make the result differ)

1. Day-count and conventions Different sources use different day-count methods. Changing the denominator (360 vs 365) changes the daily rate and therefore the rollover.

2. Provider methodology The “interest difference” intuition may not match exactly because the provider’s swap terms incorporate their own computation and pricing conventions.

3. Triple-swap timing and size Triple-swap changes rollover amounts on specific rollover dates. If you compare two calendar days without accounting for these conventions, the numbers may look inconsistent.

4. Execution and costs Your realized results depend on spread, any commissions, funding-related entries, and how the platform marks the position during rollover. Rollover is only one component of holding costs.

5. Statement verification is scenario-dependent Rollover can appear as debits or credits depending on rate conditions and position direction. Historical relationships do not establish future behavior.