XRPL IOU Fee Rate calc.

const BigNumber = require('bignumber.js') const availableBalance = new BigNumber(10) const currency = { transfer_rate: '1050000000' } const one = new BigNumber(1) const rate = new BigNumber(currency.transfer_rate).dividedBy(10000000).minus(100) // Percentage const fee = new BigNumber(availableBalance).times(one.minus(one.dividedBy(one.plus(rate.dividedBy(100))))) const maxCanSend = availableBalance.minus(fee).toNumber() console.log({ rate: rate.toNumber(), fee: fee.toNumber(), maxCanSend })