# Weighted Math

## Overview

Weighted Math is designed to allow for swaps between any assets whether or not they have any price correlation. Prices are determined by the pool balances, pool weights, and amounts of the tokens that are being swapped.

Balancer's Weighted Math equation is a generalization of the

For more formulas and derivations of the below formulas, please refer to the Balancer Whitepaper.

## Implementations

### TypeScript

Developers can use the TypeScript math implementations used by the Smart Order router

### Python

There are also Python implementations in progress

## Invariant

The value function

Where

ranges over the tokens in the pool is the balance of the token in the pool â€‹is the normalized weight of the tokens, such that the sum of all normalized weights is 1.

## Spot Price

Each pair of tokens in a pool has a spot price defined entirely by the weights and balances of just that pair of tokens. The spot price between any two tokens,

is the balance of token , the token being sold by the swapper which is going into the pool is the balance of token , the token being bought by the swapper which is going out of the pool is the weight of token is the weight of token

### Spot Price with Swap Fees

When we consider swap fees, we do exactly the same calculations as without fees, but using

## Swap Equations

### outGivenIn

When a user sends tokens

Info

If you're computing this value yourself, remember that the pool collects swap fees as a percentage of the **input token**. In the equation above,

### inGivenOut

It is also very useful for swappers to know how much they need to send of the input token