Stablecoin pairs explained: USDT and USDC quote currencies
In a pair like BTC/USDT, USDT is the quote currency: the unit the price is shown in and the currency you pay or receive. BTC/USDT and BTC/USDC are two separate markets, each with its own order book. Their prices sit close together but rarely match exactly. The gap comes from the USDC/USDT rate and from each book’s own liquidity.
This guide explains how quote currencies work, why prices differ, and how to convert between them. Examples use illustrative prices.
Base and quote
Every trading pair has two parts, written BASE/QUOTE.
- Base currency: the asset being bought or sold. In BTC/USDT, it is BTC.
- Quote currency: the unit the price is expressed in. In BTC/USDT, it is USDT.
A price of 60,000.00 on BTC/USDT means 1 BTC costs 60,000.00 USDT.
- Buying BTC/USDT spends USDT and receives BTC.
- Selling BTC/USDT spends BTC and receives USDT.
Order quantity is usually entered in the base currency, such as 0.1 BTC. Some order forms also let you enter an amount in the quote currency, such as 1,000 USDT. Check which unit the form is using before you confirm.
Why stablecoins are common quote currencies
Stablecoins such as USDT and USDC are tokens designed to track the US dollar. Quoting in a stablecoin lets traders read prices in dollar terms while staying on-chain or on-venue, without converting back to bank currency.
Many venues list the same coin against several quote currencies, for example BTC/USDT, BTC/USDC and BTC/USD. Each is its own market.
This guide covers how pairs work. It does not assess any stablecoin’s design, reserves or risk.
Why the same coin has slightly different prices
Three things keep BTC/USDT and BTC/USDC close but not identical.
1. The stablecoins trade against each other
USDC and USDT have their own market, USDC/USDT. Its price is usually very close to 1.0000, but it moves in small amounts.
Say BTC/USDT is 60,000.00 and USDC/USDT is 0.9995, meaning 1 USDC buys 0.9995 USDT. The equivalent BTC price in USDC is:
60,000.00 ÷ 0.9995 = 60,030.02 USDC
So a BTC/USDC price around 60,030 is consistent with BTC/USDT at 60,000. The coin has not changed value; the measuring unit has.
2. Each pair has its own order book
The two books have different buyers, sellers, depth and spreads. A large order in one book moves that book’s price without touching the other. See how to read an order book.
3. Arbitrage narrows the gap, not to zero
When the gap grows larger than trading costs, some traders buy in one market and sell in the other. That activity pulls prices back together. Fees, transfer times and depth mean a small gap usually remains.
Conversion example: two routes to the same trade
A trader holds 1,000.00 USDC and wants BTC. There are two routes. The example assumes a trading fee of 0.1% per trade, taken from what is received. Fee schedules vary by venue.
Route A: buy directly on BTC/USDC at 60,030.02
- BTC before fees: 1,000.00 ÷ 60,030.02 = 0.016658 BTC
- Fee: 0.016658 × 0.001 = 0.000017 BTC
- BTC received: 0.016642 BTC
Route B: convert to USDT, then buy on BTC/USDT at 60,000.00
- Convert: 1,000.00 USDC × 0.9995 = 999.50 USDT
- Conversion fee: 999.50 × 0.001 = 1.00 USDT, leaving 998.50 USDT
- BTC before fees: 998.50 ÷ 60,000.00 = 0.016642 BTC
- Fee: 0.016642 × 0.001 = 0.000017 BTC
- BTC received: 0.016625 BTC
Route B delivers about 0.000017 BTC less. At $60,000.00, that is about 0.000017 × 60,000 = $1.00, roughly the cost of the extra trade.
Here the two quoted prices were exactly in line, so the extra fee decided it. In real markets, spreads and depth in each book also shift the result. For larger orders, slippage can matter more than the fee; see slippage explained.
Quote currency on derivatives
Perpetual futures also have a settlement currency, often called the margin asset.
- A USDT-margined perpetual takes margin in USDT and settles P&L and funding in USDT.
- A USDC-margined perpetual does the same in USDC.
A trader holding only USDC who opens a USDT-margined contract may first need to convert. The contract’s terms, tick size and funding schedule can also differ between the two versions. Check your venue’s contract specification. For how settlement works more broadly, see spot vs futures vs perpetuals.
Comparing pairs at a glance
| Question | Where to look |
|---|---|
| What is the price in each quote currency? | Each pair’s last price and best bid/ask |
| Are the prices consistent? | Divide one by the USDC/USDT rate and compare |
| Which book is deeper? | Order book depth near the best price |
| What does each route cost? | Spread, fees per trade, number of trades needed |
| What currency settles a perp? | The contract specification |
Common mistakes
- Comparing prices across quote currencies as if they were the same unit. Adjust for the stablecoin rate first.
- Forgetting the conversion fee. Two trades mean two fees.
- Entering quantity in the wrong unit. “1,000” can mean 1,000 USDT or 1,000 of the base coin, depending on the form.
- Posting margin in the wrong stablecoin. A USDC balance does not fund a USDT-margined position on most venues without conversion.
Related
Fees shape which route is cheaper; see maker vs taker fees. For the order types used on each pair, read market, limit, stop and stop-limit orders explained.
Frequently asked questions
What is a quote currency?
In a pair written as BASE/QUOTE, the quote currency is the unit the price is expressed in. In BTC/USDT, a price of 60,000 means one BTC costs 60,000 USDT. Buying spends the quote currency; selling receives it.
Why is BTC priced differently in USDT and USDC?
The two pairs are separate markets. USDT and USDC trade against each other at a rate that is close to, but not always exactly, one to one. Each pair also has its own order book, depth and spread, so prices can drift slightly apart.
Is it cheaper to trade BTC/USDT or BTC/USDC?
It depends on the venue's fee schedule, the spread and depth in each book, and whether you first need to convert one stablecoin into the other. Converting adds a trade and a fee. Comparing the full cost of each route gives the answer for a given order.
Does a perpetual's quote currency matter?
Yes. A USDT-margined perpetual settles profit, loss and funding in USDT, and a USDC-margined one settles in USDC. The margin you post and the balance that changes are in that currency. Check your venue's contract specification.
Hippo provides information, not investment advice.
Part of our guide: Perpetual futures funding rates, explained
