Gas Limit

The gas limit is a parameter set by users (or wallets on their behalf) that defines the maximum amount of computational effort they're willing to consume for a blockchain transaction. On Ethereum, every operation (transferring tokens, executing smart contract functions, storing data) consumes a specific number of gas units. The gas limit acts as a safety mechanism — if a transaction tries to consume more gas than the limit, it reverts, preventing users from accidentally spending unlimited fees on stuck or infinite-loop transactions.

Different operations require different gas amounts: a simple ETH transfer requires exactly 21,000 gas, a basic ERC-20 token transfer needs ~65,000 gas, and a complex DeFi operation (like a multi-hop swap through several liquidity pools) might require 200,000-500,000+ gas. The actual cost in ETH is calculated as: gas used × gas price (in gwei). Setting the gas limit too low causes transaction failure (but gas is still consumed for the computation performed); setting it too high wastes no money — only gas actually consumed is charged.

Ethereum also has a block gas limit (currently ~30 million gas per block), which determines how many transactions can fit in each block. This is a critical network parameter — increasing the block gas limit allows more throughput but requires validators to process more data, potentially increasing hardware requirements and reducing decentralization. This fundamental tension drives the development of Layer 2 scaling solutions.