uniswap – Understanding Price Differences Between Pair Contracts and Swap Pair Contracts

pairingsswapsuniswap

I created a few bots to pull data from Uniswap. For example, using ETH/DAI. Even though the pairs are the same, the contract ID's are different for pairs and swap. Why is it that the swap price predominantly lower than the pair price?

Best Answer

The pair price is the price that you will get if you trade an infinitesimally small amount. It is a theoretical equilibrium price that you will never get in practice.

The swap price is the price that you will get if you swap the given amount (1 Eth in your screenshot). The swap price will always be lower than the pair price because of the "price impact" (something referred to as slippage), which is inherent to how AMM work. The bigger the swap in relation to the size of the pool, the worst price you will get. You can learn more about it here. The swap price most likely also include the swap fee that you pay to the liquidity providers (often 0.2% or 0.3%).

Related Solutions

Uniswap API – How to Query for Pair ID of a Chosen Token

You can write a query to filter all the liquidity pairs on Uniswap and get the pair address

    {  pairs (where :{token0 : "0x0f7f961648ae6db43c75663ac7e5414eb79b5704", token1 :"0xc02aaa39b223fe8d0a0e5c4f27ead9083c756cc2"}) { // token1 is the ethereum address
    id
    createdAtTimestamp
    volumeUSD
    //any other field you want
  }
}

[Ethereum] Computing the Uniswap V3 pair price from Q64.96 number

    function getPrice(address tokenIn, address tokenOut)
        external
        view
        returns (uint256 price)
    {
        IUniswapV3Pool pool = IUniswapV3Pool(factory.getPool(tokenIn, tokenOut, FEE);
        (uint160 sqrtPriceX96,,,,,,) =  pool.slot0();
        return uint(sqrtPriceX96).mul(uint(sqrtPriceX96)).mul(1e18) >> (96 * 2);
    }

Returns spot price with 1e18 precision. Be careful to use spot price because it is a subject for a flash loan attacks. Either use TWAP price or check that price hasn't move much before using spot price. Also, I haven't tested this code for precision loss and upper/lower boundaries. Because Uniswap v3 use Q64.96 notion for decimals but it doesn't seem that practical. The output of the function is a number with e18 precision. It depends which decimal lib you use in your project.

Best Answer

Related Solutions

Uniswap API – How to Query for Pair ID of a Chosen Token

[Ethereum] Computing the Uniswap V3 pair price from Q64.96 number

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