Binance and Kraken don't calculate spot shorting borrow costs the same way. Binance charges interest by the hour, with rates that float based on market conditions — you pay interest in whichever coin you borrow. Kraken charges a fixed opening fee and a fixed rollover fee for spot margin shorting. The rollover fee starts 4 hours after opening, and the rate is locked in when your order fills. If you only look at "shorting BTC," Kraken's BTC rollover rate is 0.0100% per 4 hours, which works out to about 0.06% per day. Binance's BTC borrow rate at any given moment could be much lower or much higher than that, depending on the real-time hourly rate shown on the margin data page. You can't compare the two by taking one platform's historical rate and applying it to the other's fixed fee. You need to compare the same coin, the same notional amount, and the same time period.
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Binance: Borrowing costs are floating, accrued hourly as simple interest
Shorting on Binance spot margin is straightforward: you borrow the coin you think will drop, sell it, then buy it back later to repay. The cost comes from the interest on that loan. Binance's margin lending rate changes once every hour based on market conditions. Interest is calculated as simple interest and accrues at each full hour, adding to your margin liability total.
After April 30, 2026, the first interest charge was adjusted: instead of charging a full hour as soon as you borrow, it now calculates based on the actual seconds between your borrow time and the next full hour. The formula is:
First interest charge = Loan principal × Hourly rate × (Actual seconds / 3,600)
After that, billing returns to full-hour settlements. Unpaid loans continue accruing interest in full one-hour units until repaid. This means the shorter your short position, the smaller that first interest charge. But once you cross a full hour mark, every subsequent hour adds a new interest charge. Repaying early only stops future interest — the charge that already triggered won't be refunded.
The rate itself floats. You can check it on the Binance margin data page or the margin trading page. Before borrowing, you can see the current hourly rate and the estimated rate for the next hour. Rates vary widely by coin. On some Binance regional sites, BTC's hourly rate might be around 0.00004%, which annualizes to less than 0.5%. Meanwhile, some smaller-cap coins can have annualized borrow costs in the double digits or higher. Shorting a major coin and shorting an obscure altcoin are completely different cost tiers — that's the first variable you need to align before comparing.
Also, if you pay interest with BNB, some pages show a 5% discount. But the discounted rate is what actually gets charged, and you need enough BNB in your account with the setting enabled. When comparing costs, use the number you'll actually be charged, not the pre-discount sticker price.
Kraken: Shorting has fixed opening and rollover fees, locked at execution
Kraken's spot margin shorting splits costs into two parts: an opening fee charged once when you enter the position, and a rollover fee that serves as the holding cost, starting 4 hours after you open. Both fee rates are determined by the coin you borrow. When you short BTC, Kraken lends you BTC from its margin pool to sell, and fees are calculated based on the amount of BTC sold.
Kraken's official page lists rates for each coin. BTC's opening fee and rollover fee are both 0.0100%. Most other coins are 0.020%, and some like Cardano are 0.026% or 0.024%. The rollover fee cycle is once every 4 hours. At BTC's 0.0100% rate, there are six cycles per day, so holding one BTC short position costs about 0.06% of notional value per day in rollover fees.
Kraken's rates can fluctuate with market conditions, but your rollover rate is locked when your order executes. It won't change mid-position due to market rate shifts. This design gives you more cost certainty than Binance: what you see at entry is what you pay for the entire holding period. You won't experience Binance-style overnight rate spikes. The tradeoff is that if market borrowing rates fall, your locked rate won't drop with them. If rates rise, you're protected.
Comparing both on the same terms
| Binance Spot Margin | Kraken Spot Margin | |
|---|---|---|
| Billing method | Hourly simple interest, floating rate | One-time opening fee + rollover fee every 4 hours |
| Rate locked? | No, may change hourly | Yes, rollover rate locked at execution |
| BTC short cost reference | Check real-time hourly rate on margin data page | Rollover 0.0100% / 4 hours, about 0.06% per day |
| First charge | Prorated by actual seconds | Opening fee charged immediately, rollover starts after 4 hours |
| Fee currency | Interest paid in the borrowed coin | BTC short fees based on BTC amount |
| Where to check | Margin data page, margin trading page, interest records | Order table shows rates, position tab shows current rollover rate |
The most common mistake is taking Binance's BTC hourly rate at one moment, multiplying by 24, and comparing that to Kraken's daily rate. Binance's rate floats — the rate you see at entry only guarantees that one hour. The next full hour could be different. Kraken's rollover rate is fixed once your order fills, so your calculated daily cost won't drift during the entire holding period. A fairer approach: first decide how long you plan to hold, then run a "what if the rate stays the same" scenario using Binance's current rate, while acknowledging that the actual result may differ. For Kraken, just use the locked rate.
Say you short 10,000 USDT worth of BTC and hold for 24 hours. On Binance, if the current BTC hourly rate is 0.00005%, 24 hours of interest is about 0.12 USDT. If the rate jumps to 0.0005%, the same position costs 1.2 USDT — a tenfold difference. On Kraken, BTC rollover is 0.0100% per 4 hours. Over 24 hours (six cycles), the fee is 10,000 × 0.0100% × 6 = 6 USDT. In this scenario, Binance's current rate produces a much lower cost than Kraken, but Binance's cost is uncertain while Kraken's is fixed. If Binance's rate spikes during your holding period, the actual cost could exceed Kraken's.
How to choose
If you're shorting BTC or ETH and holding for a short time (a few hours to a day or two), Binance's floating rate is usually lower under normal market conditions. The prorated first interest charge is also slightly friendlier for short-term traders. The tradeoff is accepting rate change risk during your holding period — especially after crossing multiple full hours, the cost could end up higher than you estimated at entry.
If you plan to hold for several days or more, or want to lock in costs at entry, Kraken's fixed rollover rate makes budgeting more predictable. You give up the chance to pay less if rates fall, but you gain protection from sudden borrow rate spikes that could force early exits or unexpected costs.
If you're shorting smaller-cap coins, the fee differences between platforms can be much larger than for BTC. Binance's rates span a wide range across coins, so you must check the current borrow rate for that specific coin before opening — don't extrapolate from BTC. Kraken's fee table covers major coins and a decent number of smaller ones, but you still need to confirm there's enough available supply in the margin pool for the coin you want to short. Otherwise your order may not fill or only partially fill.
Whichever platform you use, there's something more important than borrow cost to check before shorting spot margin: available borrowable supply and liquidation risk. No matter how low the borrow rate is, if there isn't enough supply to build your desired position, or if price swings trigger liquidation, the cost comparison becomes meaningless. Before opening a position, check the current available borrow amount on the borrow page, and confirm your liquidation price and margin ratio on the position page. That information affects your position's survival more directly than the interest rate itself.
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References
- Binance·Binance Margin Dynamic Interest Rate System FAQ, 2026-11-02
- Binance·Binance Margin will Optimize the Interest Rule for Loans, 2026-11-02
- Kraken·What are the fees (opening and rollover) for margin trading?, 2026-11-02
- Binance·Cross Margin Data (regional margin rate page for observing BTC and USDT hourly rate levels), 2026-11-02
