Bonding Curve

What is Bonding Curve?

A bonding curve is a rule—usually implemented in a smart contract—that automatically prices a token as a function of how many tokens exist (the token’s supply). Instead of relying on an order book or a market maker on an exchange, users can buy tokens from the contract (minting new supply) or sell tokens back to the contract (burning supply), with the price updating deterministically after every trade.

How Does Bonding Curve Work?

At the core of a bonding curve is a mathematical function that maps supply to price. The contract holds (or accounts for) a reserve asset—often ETH, a stablecoin, or another base token. When someone buys, they deposit the reserve asset into the contract and receive newly minted tokens. When someone sells, they return tokens to the contract, which burns them and pays out reserve assets according to the curve’s rules.

A simplified step-by-step flow looks like this: 1. A curve is defined: The project chooses a pricing function (for example, linear, exponential, or another custom curve) and parameters such as starting price and slope. 2. A reserve mechanism is set: The contract specifies what asset backs redemptions (e.g., ETH) and how much of each purchase is retained in reserves. 3. Buying (minting) happens: A user sends the reserve asset to the contract. The contract calculates how many tokens to mint based on the current supply and the curve. After minting, supply increases, and the next buyer faces a higher (or differently adjusted) price. 4. Selling (burning) happens: A user sends tokens back. The contract calculates the payout from reserves based on the new supply after burning. Supply decreases, and the price moves down (or adjusts according to the curve).

The “shape” of the bonding curve matters because it determines how quickly price changes as supply grows. A linear curve increases price at a steady rate per token minted. An exponential curve can make early tokens relatively cheap but becomes expensive quickly as supply expands. Other shapes (including logarithmic or piecewise curves) can be designed to match a project’s goals—such as smoother early distribution or stronger scarcity later.

A helpful analogy is a venue selling tickets with a posted rule: “Each time a ticket is sold, the next ticket costs a bit more.” There’s no haggling and no need to find another buyer; the venue itself is always willing to sell at the current posted price and buy back according to its refund policy. In crypto, the smart contract plays the role of the venue, and the curve is the posted pricing rule.

Bonding Curve in Practice

Bonding curves show up in DeFi and Web3 token design wherever teams want and without depending on centralized exchanges. They’re commonly used for: