# Swap

SpiritSwap provides users a simple way to swap tokens on Fantom via automated liquidity pools. In a swap, one token is sold to buy another token. The rate of the swap is determined by the AMM with the equation:

$x*y=k$

Where

*x*= the number of $AAA tokens,*y*= the number of $BBB tokens, and*k*is a constant. The trader is charged a 0.3% fee to make a swap.Figure 1. Example of a swap on SpiritSwap.

In Figure 1, a trader is swapping $AAA token for $BBB tokens. The trader sends 100 $AAA tokens to the AMM. A 0.3% fee is applied and 0.3 $AAA tokens are not included in the swap. The remaining 99.7 $AAA tokens are swapped in the AMM to $BBB tokens. Since the AMM will be losing $BBB tokens, it must gain $AAA tokens to keep

*k*constant. The equation:$(1,000+99.7)*(10-y)=10,000$

Can be solved for

*y*to give the number of $BBB tokens that the trader will receive. The 0.3% fee of 0.3 $AAA tokens are directly added to the liquidity pool reserves, slightly increasing the value of*k.*Last modified 1yr ago