English

Find a broker

Home / Tools / Calculators / Margin interest calculator

Margin interest calculator

What it costs to borrow the part of a position you did not fund yourself, per day and over the whole hold.

Hold a leveraged position overnight and you are borrowing the difference between the position and the money you put up. That borrowing accrues interest every night the position stays open.

It is small on a day trade and it is not small over a quarter, which is why a position that made money on the chart can lose it on the statement.

account ccy

The full exposure, not the margin.

account ccy

Everything above this is borrowed.

%

Usually a benchmark rate plus the broker's markup. Check the financing schedule rather than the headline.

days

Brokers use one or the other depending on the instrument. 360 makes the daily figure slightly larger.

Interest over the hold$593.75
Amount borrowed
$95,000.00
Per day
$19.79
As a share of your own money
11.9%
The number that decides whether the hold was worth it.

A model, not a quote. Every figure here comes from what a broker publishes or what you type, and real fills, spreads and rates move.

The formula

Borrowed
position value − your own funds
Daily interest
borrowed × annual rate ÷ day-count basis
Total
daily interest × days held

How to use it

  1. Enter the full position valueNot the margin. The exposure is what determines the borrowing, and confusing the two is the single most common error in leveraged trading.
  2. Enter what you actually put upThe difference between the two is the loan. Put up the whole position and there is nothing to borrow and no interest to pay.
  3. Find the real rateBrokers publish financing as a benchmark plus a markup, and the markup is frequently larger than the benchmark. The headline rate on the marketing page is rarely the rate on the statement.
  4. Set the holding periodInterest is the cost that grows with time rather than with size, which is what makes it invisible on a day trade and decisive over months.

A $100,000 position held for a quarter

Put up $5,000 of your own money against a $100,000 position and you have borrowed $95,000. At 7.5% on a 360-day basis that is $19.79 a day.

Held for 90 days, the interest comes to about $1,781, which is 36% of the $5,000 you committed. The position has to make that much before it makes anything.

The same position held for two days costs $40, which nobody notices. Time is the whole variable.

Simple accrual, not compounded

Interest is calculated on the original borrowing throughout rather than being rolled into the loan, because brokers debit financing to the account rather than adding it to the position.

Rates also move. A figure entered today applied across ninety days assumes a rate that will not change, and floating rates do.

Common questions

Is this the same as swap on a forex position?

Related but not identical. Forex swap is a financing adjustment that can be a credit or a debit depending on the rate differential between the two currencies. This calculates a one-directional borrowing cost, which is closer to how share and CFD margin lending works.

Why does the day-count basis matter?

Dividing by 360 rather than 365 makes each day about 1.4% more expensive. It is small, it is real, and it is in the contract.

Should I include the interest when working out my return?

Yes. A position that gained 5% while paying 4% in financing returned 1%. The financing does not appear on the chart.

Read more

Other broker fee and cost calculators