here is quick question. From uniswap pool, which one is base token? token0 or token1?

2 Answers 2


Price in Uniswap pools is tracked in terms of token1/token0, so token1 is the numeraire token if that's what you're asking.

  • like when i flashloan from the pool, the loan must be repayed by base token. this is the reason i ask the question. so i must pay the loan in token1. Right? Oct 29 at 14:50
  • @BirukDamte you can make a flash loan or a flash swap with Uni, but where does the name "base" comes from?
    – kfx
    Oct 29 at 17:35
  • from youtube tutorial. Any way ur answer helped me. Thanks bro Oct 29 at 19:14

There is no on-chain way to determine which token is a base token or which is a quote token if token0 and token1 are mapped to normal trading pairs.

The trading pair base-quote token order is a human-made concept for making natural reading easier. Thus, you need to have your own rules that determine which of the tokens is a quote token (determining quote is usually easier than determining base).

Here are some rules that can help you

  1. First determine if a token is stablecoin. Have a hierarchy of stablecoins to determine a "better stablecoin for stable-stable pairs.

  2. Then check for a native token. A quote token is usually ETH (WETH), MATIC (WMATIC), AVAX (WAVAX) or similar. All "large cap tokens", including BTC (WBTC) are good quote tokens.

  3. If you still cannot determine then flip a coin. However, in this case, it's an exotic pair you probably do not want to trade in the first place.

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