Why swapping USDT for USDC sometimes gives you less than a dollar

05 September 2026

The short answer is that USDT and USDC are different assets with separate supply, demand, and liquidity pools, so their market prices diverge slightly from $1 at any given moment. That divergence means a swap between them almost never exchanges at exactly 1:1.

Why the price isn't exactly $1

Both USDT and USDC are designed to trade near $1, but neither is a perfect mechanical peg. The peg is maintained by arbitrageurs who buy when the price dips below $1 and sell when it rises above, profiting from the difference. This process keeps prices close to $1, but not identical to it.

On most markets, USDT and USDC trade in a range of roughly $0.997 to $1.003. A swap that exchanges USDT for USDC will reflect whatever the current market rates are for both tokens at the moment of execution. If USDT is trading at $1.001 and USDC at $0.998, swapping $100 of USDT will yield about $99.70 of USDC. The difference is simply the market price, not a hidden fee or a broken peg.

Liquidity depth matters

The size of your swap also affects the rate. Every liquidity pool - whether on a decentralized exchange or the internal order book of the exchanger - has a finite depth. A small swap of $50 will typically get a rate very close to the quoted market price. A swap of $50,000 may push the price against you, especially on a chain or pool where liquidity for that pair is thin. The larger the trade relative to available liquidity, the more you lose to slippage.

Slippage is not a fee. It is the mathematical consequence of moving price along a curve. The exchanger will show you an estimated rate before you confirm; the final rate depends on how the pool shifts during the milliseconds your transaction takes to settle.

Network fees and timing

The swap itself incurs a network fee (gas) on whatever chain you use. That fee is separate from the exchange rate. On Ethereum mainnet, gas can be several dollars; on a chain like Polygon or Arbitrum, it is often a few cents. The gas cost is deducted from your input or added to your output, depending on how the exchanger structures the transaction. It is not part of the swap rate, but it reduces what you ultimately receive.

Timing also matters. Volatile market conditions - such as a sudden depeg event or a large order hitting the same pool - can shift rates between the moment you submit the transaction and the moment it confirms. Slippage tolerance settings on decentralized exchanges let you cap how much worse the rate can get, but if the price moves beyond that cap, the swap fails and you pay gas for nothing.

Stablecoins are not fungible with each other

USDT and USDC are issued by different companies, backed by different reserves, and subject to different regulatory scrutiny. That creates slight but persistent differences in perceived risk. During periods of market stress, USDT has historically traded at a small discount to USDC, or vice versa. This is not a glitch. It is the market pricing in the distinct risk profiles of two separate instruments.

The exchanger does not control these rates. It sources liquidity from multiple pools and order books, aggregates them, and presents you with a rate. That rate will always be slightly worse than the best available on any single venue, because the exchanger takes a small spread to cover its own costs.

What to read next

If you are moving between stablecoins and volatile assets, or between stablecoins on different chains, the hub page "Swapping into and out of stablecoins" explains the broader mechanics of how these trades work across networks and what hidden costs to watch for.

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