How Rollover Is Calculated for AUD/JPY: Interest Inputs and Triple-Swap Conventions

Direct answer

Rollover for AUD/JPY is an overnight adjustment meant to reflect the cost or credit of holding a currency position, driven mainly by the interest-rate differential between the two currencies and the contract’s rollover convention. The mechanics can include additional provider-specific adjustments such as a markup/spread on the rollover rate and a “triple-swap” rule around certain rollover days.

Mechanism or definition

Rollover (swap) is the interest-related part of the P&L that occurs when a forex position remains open past the platform’s daily settlement time. For a currency pair, the concept is usually explained as:

Interest-rate inputs: Each currency has an interest-rate benchmark (often a short-term interbank or central-bank policy rate, or a derived rate used by the provider). The pair’s rollover is largely driven by the difference between the two currency interest rates.
Position direction: Whether you receive or pay rollover depends on whether you are long one currency and short the other. If the currency you are effectively “long” has the higher benchmark rate, rollover is often more favorable; if it has the lower benchmark rate, rollover can be negative.
Annualized-to-overnight conversion: The benchmark rates are typically annualized. To compute an overnight adjustment, they are converted into a per-day amount using the contract’s day-count convention (for example, a division by a number of days in a year) and the platform’s overnight timing.
Triple-swap convention: For some brokers/platforms, the rollover that happens over a weekend (or over a day with extended settlement) may be larger—commonly described as triple the normal amount—because more than one day of interest accrues at once.

Important simplification: Many educational explanations treat rollover as “interest differential × position size × an overnight factor.” In practice, the provider converts inputs into a tradable swap rate using internal tables and contract rules, so the displayed rollover can differ even if two providers use similar benchmark concepts.

Evidence or example (with stated assumptions)

Because there are no live provider rules included here, the following is a checkable example that shows the structure of the calculation. It is not an exact AUD/JPY number.

Assumptions for illustration

You hold an AUD/JPY position overnight.
The provider uses an interest-rate differential model based on annualized benchmarks.
A simplified overnight conversion uses a factor of 1 day / 360 (a common educational simplification; your provider may use a different day-count).
The provider applies no additional markup (real providers often do).
“Triple-swap” applies when the rollover is posted on a rollover day that covers multiple calendar days.

Step 1: Compute the differential

Let r_AUD be the annualized AUD benchmark rate used by the provider.
Let r_JPY be the annualized JPY benchmark rate used by the provider.
Compute the annual differential: Δr = r_AUD − r_JPY.

Step 2: Convert to an overnight rate

Compute a simplified overnight factor: f = (1 / 360).
Overnight interest differential component: Δr × f.

Step 3: Apply direction

If your position is structured such that you are effectively long AUD versus short JPY, the sign of the adjustment follows the sign of Δr; if the direction is reversed, the sign flips.

Step 4: Apply triple-swap when applicable

On a triple-swap posting day, the overnight component may cover roughly three days in one charge/credit.
In the simplified model, you would multiply the normal overnight component by 3.

Where the real-world number can differ

Providers may use different day-count conventions.
They may incorporate contract-specific parameters and internal rollover rate tables.
They may include a markup (or other adjustments) on top of the benchmark differential.
The exact posting can depend on the platform’s server time and the order’s open/close timestamps.

If you want to independently verify the calculation at a practical level, the best method is to compare rollover postings across consecutive nights using your platform’s displayed swap rate (or swap formula in contract notes, if provided) while keeping everything else constant.

Limitations and risks

Provider rules vary: The same currency pair can show different rollover amounts across platforms because each provider may implement its own day-count method, markup, and triple-swap timing. - Timing and failure modes: Rollover can be posted according to the platform’s cutoff time in server time.