Small balance, fixed fee: when does the interest catch up?

At 100 USDT it takes 73 days of interest to earn back a single fee. The rate matters less than you might expect. Halve the APR on 3,000 USDT to 2.5% and both fees are back in about 9.7 days; double it on 100 USDT to 10% and earning back both fees still takes 73 days.

Already there, or moved in for the yield?

If the money is already sitting in your exchange account, such as change from a trade or a small amount you weren’t planning to touch, subscribing costs no transfer fee and the table doesn’t apply. From the day accrual starts, whatever it earns is extra, though the product’s own risks don’t go away (see can you lose principal).

If you’d be moving it over from your own wallet or another platform just to earn on it, you pay a fee to bring it in and most likely another to take it out. That’s the last column.

People get this wrong both ways. Some move money in for the yield and compare APRs without counting the fees. Others treat money that was already there as if it had a fee to earn back, and leave small change sitting idle. The difference is whether you’d pay the fee anyway, or only because you want the money to earn.

Where the day counts come from

Days to earn back a fixed fee = fee × 365 ÷ (balance × APR). For the top row, 1 × 365 ÷ (100 × 5%) = 73 days; with a fee each way, swap the 1 for a 2 and you get 146. Daily interest is balance × APR ÷ 365, so 100 × 5% ÷ 365 ≈ 0.0137 USDT.

At lower rates the wait gets long. At 2% APR, a full year on 100 USDT earns 2 USDT, exactly the cost of two 1 USDT fees, so after twelve months you are back where you started.

The table assumes interest runs on the whole balance from the day you subscribe, and in practice it can start later. The flexible-products guide says “Bonus Tiered APR rewards start accruing the day after your subscription is made, starting at 00:00 UTC”, so on products with a bonus tier that portion begins a day late and the shorter day counts in the table stretch by about a day.

This is simple interest, and daily compounding adds very little at this size. At 5% for 73 days, 100 USDT earns 1.0000 USDT simple and about 1.0049 USDT compounded daily. The APR vs APY piece covers how the two convert. For your own numbers, get one day’s interest from the earnings calculator and divide the fee by it.

The two minimums that catch small balances

• Subscriptions have a minimum. The guide “Get Started with Binance Simple Earn Flexible Products” lists “Minimum: The minimum amount of tokens required for a subscription.” That line gives no figure; each product page shows its own, so check before you subscribe.
• Withdrawals have a minimum too. “Crypto Withdrawal Fees on Binance” says: “Please note that there is a minimum amount for each withdrawal request. If the amount is too little, you won’t be able to request a withdrawal.” Scatter small amounts around and you can end up holding coins you cannot send anywhere in one go.

For the real-time part of the rate, the same guide says rewards are accrued every minute and “rounded to eight decimal places”. At the table’s assumptions, 100 USDT earns about 0.0000095 USDT a minute, more than 900 times the smallest eighth-decimal step of 0.00000001. Only a very low real-time rate on a very small balance falls below half a step: under about 0.053 USDT at 5%, or about 2.6 USDT at 0.1%, each minute’s interest is less than 0.000000005 USDT and may round to zero.

When to subscribe, and when to leave it where it is

Money already in your account costs next to nothing to put into a flexible product. You get a little interest, plus one run through subscribing, accruing and redeeming. Your first go at any earn product should use an amount you wouldn’t miss, which is also what your first time using Earn recommends.

If you’d have to move it in, set the day count against how long the money will stay. Say you plan to hold for 60 days. At 100 USDT, earning back both fees takes 146 days, and 60 days of interest comes to about 0.82 USDT, well short of what the two transfers cost. At 3,000 USDT, both fees are back in about 4.9 days; 60 days earn about 24.7 USDT, roughly 22.7 USDT once the fees are paid (all at the assumed rate, counting from the day you subscribe).

If it were our money, we would only put in change that is already in the account. A small amount that needs a transfer would stay where it is once the day count runs past how long we plan to hold it.

The table uses a stablecoin. With a coin whose price moves, one day’s swing can outweigh a year of interest, which is a separate calculation covered in coin or dollar terms.