Margin Interest: How Binance Charges Borrowing by the Hour

Two costs, one of which is on the fee page

A margin trade is financed. Part of the position is paid for with the trader’s collateral, and part is paid for with a loan from the venue. The trading fee is charged when the order fills and is visible in the fill record. The interest is charged for the loan, accrues over time, and appears somewhere else entirely.

That separation is the source of most margin-cost surprises. A trader who calculates a round trip from maker and taker rates has calculated the fee, not the financing. If the position stays open for a day, the interest can exceed the fee. If the rate moves against them, it can exceed it by a wide margin.

Binance’s margin documentation describes the mechanism in unusual detail, including a rule change that took effect on 2026-04-30. The details are worth reading because they decide the size of the second bill.

Simple interest, hourly, at a rate that moves

The first property is that the interest is simple, not compounded. Binance says users are “charged simple interest for their borrowings hourly.” The principal does not grow by the interest and then earn interest on the larger amount; each hour’s charge is calculated on the principal.

The second property is that the rate is dynamic. “Margin loan interest rates will change every hour based on current market conditions.” The rate is not a fixed annual percentage divided by 8,760. It is an hourly rate that the venue resets, and the rate that applies to the next hour may differ from the one that applied to the last.

The third property is the accrual boundary. Interest “accrues at the start of each hour (e.g., 13:00, 14:00)” and is “added to their total margin debt every time it accrues.” The debt grows; it is not paid from a separate cash balance unless the account is repaid.

Those three properties produce a cost that is easy to underestimate. A rate quoted as 0.0004% per hour looks negligible. Multiply by 24 hours and it is 0.0096% per day; multiply by 365 and it is about 3.504% per year at a constant rate. The rate is not constant, but the arithmetic shows why an hourly figure is not the same thing as a small figure.

The 2026 rule change: the first hour is prorated

Before 2026-04-30, Binance charged a full hour’s interest the moment funds were borrowed. The FAQ describes the old behaviour: “The system automatically accrues one hour’s interest when you borrow funds,” and then a new hour’s interest accrues at the start of each subsequent hour. Borrow at 13:55 and repay at 14:30, and the account had been charged two hours.

The rule effective 2026-04-30 08:00 UTC changed the first charge. Binance now calculates it “on a prorated basis” using the “actual number of seconds between the borrowing time and the next hourly settlement time.” The formula is:

First interest = Principal amount * Hourly interest rate * (Actual seconds / 3,600)

The FAQ’s worked example is precise. Borrow 10,000 USDT at 05:30:49 at a 0.0004% hourly rate. The seconds until 06:00 are 1,751, so the first charge is 10,000 × 0.000004 × (1,751 / 3,600) = 0.01945556 USDT.

The change is small in absolute terms and large in behaviour. A trader who borrows for a few minutes no longer pays a full hour for the privilege. But the proration applies only to the first period. After that, the ordinary hourly rule resumes.

The full-hour periods that follow

After the first charge, Binance charges “for full hours until repayment.” The formula is:

Periodic interest = Principal * Hourly interest rate * Number of subsequent interest-bearing hours
Total interest = First interest charge + Total Periodic Interest

Interest is “rounded up to 8 decimal places,” which is a rounding convention rather than a material cost, but it explains why a calculated value and the displayed value can differ in the last digit.

The practical consequence is that the timing of a repayment matters more than the size of the first charge. If a balance remains at a settlement time, “the system will charge interest for the next full 1-hour interest period.” Repaying at 06:01 after a 06:00 settlement does not undo the 06:00 charge; it stops the 07:00 charge. Binance states the same rule more directly: “once the first interest period is triggered, it is non-refundable,” and “even if the user repays early within that hour, the interest for the entered interest period will still be charged.”

So the cost of a loan is driven by how many hourly boundaries it crosses, not by how many minutes it was open. A loan held for 61 minutes can cross two settlement times and pay two full hours after the prorated first period. A loan held for 59 minutes may cross one.

A worked cost table

The arithmetic is easier to see with a table. Take a 10,000 USDT principal borrowed at 05:30:49, so the first period covers 1,751 seconds. The subsequent full hours are charged at the same hourly rate for illustration.

The rates are illustrative, not Binance’s current rates. The point is the shape: the first charge scales with the seconds, the later charges scale with the hours, and the hourly rate multiplies both.

A position that stays open for a week crosses 168 hourly settlements. At 0.01% per hour, the interest on 10,000 USDT is about 168 USDT before any rate change. That is larger than the round-trip trading fee on most pairs, and it is the number a fee calculator that only knows maker and taker rates will miss.

Cross and isolated: same method, different collateral

Binance’s isolated margin guide uses the same first-interest formula, prorating by the seconds until the next whole hour, and then charges hourly at each whole hour. The dynamic-rate FAQ describes the method for Binance Margin generally. The interest calculation is not the difference between the two modes.

The difference is what stands behind the loan.

• Cross margin uses the account’s broader balance as collateral. A loss on one position can be covered by assets elsewhere in the account, which is why cross margin can support a larger position for the same equity — and why a single bad position can put the whole account at risk.
• Isolated margin confines the collateral to the pair’s own margin. A loss in that pair cannot reach the rest of the account, but the pair’s margin is the entire buffer, and it can be exhausted while other assets sit untouched.

Interest interacts with both through the debt. Because accrued interest is added to the total margin debt, unpaid interest raises liabilities. A margin level that compares assets to liabilities therefore falls as interest accrues, even if the position’s mark price has not moved. Binance’s FAQ recommends monitoring “both the applicable interest rates and your margin level” and warns about “potential liquidation from significant interest rate changes and/or accumulated interest accrued over time.”

That is the mechanism a trader is most likely to miss: interest is not only a cost, it is a slow increase in the liability side of the margin calculation. A position that is comfortably collateralised at entry can become less so simply because it stayed open.

What this means for a trade plan

Three habits follow from the mechanics.

Price the holding period, not just the entry. A maker fee is paid once per fill; interest is paid per hour. A strategy with a two-hour holding period and a 0.01% hourly rate pays about 0.02% in interest on the borrowed portion, which may be comparable to the trading fee. A strategy with a two-week holding period pays about 3.36% at that rate, which dominates the fee.

Repay on the hour, not after it. Because the settlement happens at the top of the hour, a repayment planned for “sometime this hour” is effectively a repayment after the next charge. If the goal is to stop accrual, the repayment has to land before the settlement, not after it.

Read the rate where it is published. The hourly rate is dynamic and is shown on Binance’s margin data page and in the account. A rate copied from a blog post is a historical number. The fee schedule guide explains how to find the trading rates; the interest rate is a separate page and a separate number.

Where interest sits among the other costs

Margin interest is one of four costs a leveraged position can carry. The others are the trading fee, the spread crossed on entry and exit, and the funding payment on perpetual futures. The Binance spot fee guide covers the trading fee; the cross versus isolated liquidation guide covers the liquidation fee that lands when a position fails. Interest is the one that accrues quietly while nothing appears to be happening.

A complete cost estimate adds all four. A partial estimate that stops at the fee page is not conservative; it is a different, smaller trade than the one being considered.

A checklist before borrowing

• Note the principal, the hourly rate shown in the account, and the time of the borrow.
• Calculate the first charge from the seconds until the next whole hour, not from a full hour.
• Count the hourly settlements the position will cross, and multiply by the full-hour charge.
• Decide the repayment time relative to the settlement boundary, not relative to a convenient moment.
• Check whether the interest is being added to debt and how that changes the margin level.
• Re-read the rate if the position stays open; an hourly rate can move.
• Do not treat the trading fee as the whole cost of a margin position.

Sources and what they support

• Binance, New Dynamic Interest Rate System for Binance Margin Trading — states that interest is simple and charged hourly, that rates change every hour, that accrual happens at the start of each hour and is added to margin debt, and gives the proration rule effective 2026-04-30 08:00 UTC, the formulas, the 8-decimal rounding, the 10,000 USDT example and the repayment rules. Page metadata shows it was updated 2026-06-16; read 2026-11-03.
• Binance, Binance Isolated Margin Trading Guide — gives the same first-interest proration formula for isolated margin and states that subsequent interest is charged hourly at each whole hour. Read 2026-11-03.

Risk note. Interest rates, the proration rule and repayment terms were read from Binance’s own pages on 2026-11-03. Rates change hourly and the venue can change the rule again; the rate that applies is the one displayed in the account. Leveraged positions can lose more than the margin posted. Nothing here is investment advice.