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Overview

RektHub uses optimized libraries for bonding curve calculations. These utilities handle the constant product math that powers price discovery and trading.
For Integrators: You typically don’t need to use these libraries directly—the BondingCurve contract handles all calculations. This reference is useful if you’re building off-chain quoters, simulators, or custom trading algorithms.

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BondingCurveMath

The core library for constant product (x × y = k) bonding curve calculations. Location: contracts/libraries/BondingCurveMath.sol

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Purpose

  • Calculate token outputs for buy orders
  • Calculate native outputs for sell orders
  • Calculate fees as percentages (basis points)
  • Pure functions—no state modifications

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Functions

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calculateBuyReturn

Calculate how many tokens a buyer will receive for a given native token input. 
function calculateBuyReturn(
    uint256 nativeAmount,
    uint256 virtualNativeReserves,
    uint256 virtualTokenReserves
) internal pure returns (uint256 tokensOut);
Parameters:
  • nativeAmount (uint256): Amount of native tokens to spend (after fees)
  • virtualNativeReserves (uint256): Current virtual native reserves in the curve
  • virtualTokenReserves (uint256): Current virtual token reserves in the curve
Returns:
  • tokensOut: Amount of tokens the buyer will receive
Formula: 
tokensOut = (nativeAmount * virtualTokenReserves) / (virtualNativeReserves + nativeAmount)
This implements the constant product formula: x * y = k Example Usage: 
// Off-chain calculation (JavaScript)
function calculateBuyReturn(
	nativeAmount,
	virtualNativeReserves,
	virtualTokenReserves
) {
	return (
		(nativeAmount * virtualTokenReserves) / (virtualNativeReserves + nativeAmount)
	);
}

// Example
const nativeIn = ethers.parseEther('0.1');
const virtualNative = ethers.parseEther('30');
const virtualTokens = ethers.parseEther('1073000000');

const tokensOut = calculateBuyReturn(nativeIn, virtualNative, virtualTokens);
console.log('Will receive:', ethers.formatEther(tokensOut), 'tokens');
Important: This calculates the raw output before considering real reserve limits. The BondingCurve contract takes the minimum of this calculation and available real tokens.

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calculateSellReturn

Calculate how many native tokens a seller will receive for selling tokens. 
function calculateSellReturn(
    uint256 tokenAmount,
    uint256 virtualNativeReserves,
    uint256 virtualTokenReserves
) internal pure returns (uint256 nativeOut);
Parameters:
  • tokenAmount (uint256): Amount of tokens to sell
  • virtualNativeReserves (uint256): Current virtual native reserves in the curve
  • virtualTokenReserves (uint256): Current virtual token reserves in the curve
Returns:
  • nativeOut: Amount of native tokens the seller will receive (before fees)
Formula: 
nativeOut = (tokenAmount * virtualNativeReserves) / (virtualTokenReserves + tokenAmount)
Example Usage: 
// Off-chain calculation (JavaScript)
function calculateSellReturn(
	tokenAmount,
	virtualNativeReserves,
	virtualTokenReserves
) {
	return (
		(tokenAmount * virtualNativeReserves) / (virtualTokenReserves + tokenAmount)
	);
}

// Example
const tokensToSell = ethers.parseEther('1000000');
const virtualNative = ethers.parseEther('30');
const virtualTokens = ethers.parseEther('1073000000');

const grossNativeOut = calculateSellReturn(
	tokensToSell,
	virtualNative,
	virtualTokens
);
console.log('Gross output:', ethers.formatEther(grossNativeOut));

// Apply 1% fee
const fee = (grossNativeOut * 100n) / 10000n;
const netNativeOut = grossNativeOut - fee;
console.log('Net after fees:', ethers.formatEther(netNativeOut));
Fee Deduction: calculateSellReturn returns the gross amount before fees. Always subtract the protocol fee (1%) to get the net amount users receive.

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calculateFee

Calculate a fee as a percentage using basis points. 
function calculateFee(
    uint256 amount,
    uint256 feeBasisPoints
) internal pure returns (uint256 fee);
Parameters:
  • amount (uint256): Amount to calculate fee on
  • feeBasisPoints (uint256): Fee in basis points (100 = 1%, 10000 = 100%)
Returns:
  • fee: Calculated fee amount
Formula: 
fee = (amount * feeBasisPoints) / 10000
Example Usage: 
// Off-chain calculation
function calculateFee(amount, bps) {
	return (amount * bps) / 10000n;
}

// Examples
const amount = ethers.parseEther('100');
const onePercent = calculateFee(amount, 100);
console.log('1% fee:', ethers.formatEther(onePercent));

const thirtyPercent = calculateFee(onePercent, 3000);
console.log('30% of fee:', ethers.formatEther(thirtyPercent));
Basis Points: 1 basis point = 0.01%. Common values: 1% = 100 bps, 5% = 500 bps, 10% = 1000 bps, 100% = 10000 bps

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Next Steps

Bonding Curves Explained

Understand the economics

Bonding Curve Contract

See how it’s implemented

Events Reference

Track trades with events

Interfaces

Contract interfaces and ABIs