Loop Gas Cost Estimator

WHAT IT DOES

Loop Gas Cost Estimator is a read-only developer tool that analyzes EVM smart contract bytecode to identify loop structures and estimate per-iteration gas costs. It detects loop patterns using opcode analysis (JUMPI + backward JUMP sequences), extracts loop body instructions, counts storage operations (SLOAD, SSTORE), external calls (CALL), memory operations (MLOAD, MSTORE), arithmetic operations (ADD, MUL), and stack operations (DUP, SWAP, JUMP). It then calculates estimated gas per iteration based on EVM gas costs, projects total gas for user-specified iteration counts, and provides optimization recommendations. The tool helps developers identify gas-heavy loops, predict transaction costs before deployment, and optimize loop-heavy functions.

HOW TO USE

Connect your EVM-compatible wallet via the BGWallet bridge and select the network where your contract is deployed. Enter the contract address and specify the number of loop iterations you want to simulate (1-1000). Click "Estimate Loop Gas Cost" to start the analysis. The tool fetches contract bytecode, scans for loop patterns using JUMPI and backward JUMP detection, extracts loop body opcodes, calculates per-iteration gas estimates, and projects total gas for your specified iteration count. Results include a summary of detected loops, per-iteration gas breakdowns (SLOAD, SSTORE, CALL, MLOAD, MSTORE, arithmetic, stack operations), estimated total gas for N iterations, estimated cost in ETH (assuming 30 gwei), and optimization recommendations. All analysis is read-only—no signatures or transactions are submitted.

TECHNICAL MECHANISM

The tool uses ethers.js v5.7.2 to fetch contract bytecode via provider.getCode(address), then performs static opcode analysis to detect loops. Loop detection scans for JUMPI opcodes (0x57) followed by JUMP opcodes (0x56) within a 40-byte window that target an earlier position in the bytecode—this pattern represents the typical loop back-edge in EVM bytecode. Once a loop is detected, the tool extracts the loop body as the bytecode between the JUMPI and the target JUMP, and analyzes each opcode within that region. Gas estimation applies approximate EVM costs: SLOAD (100 gas), SSTORE (2000 gas), CALL (700 gas), MLOAD and MSTORE (3 gas each), ADD (3 gas), MUL (5 gas), DUP (3 gas), SWAP (3 gas), JUMP (10 gas), plus a base per-iteration overhead of approximately 20 gas plus 2 gas per body byte. The tool projects total gas as base transaction cost (21000 gas) + loop setup overhead (500 gas) + (per-iteration gas × iteration count). All estimates are static and deterministic, enabling consistent comparison across different contract versions.

WHAT IT CANNOT SEE

This tool has fundamental limitations that users must understand. It cannot determine exact loop iteration counts without executing transactions or simulating state—the tool assumes the iteration count you provide as a simulation parameter. It cannot analyze loops with dynamically computed bounds that depend on runtime state (e.g., loops where the number of iterations depends on storage values or external calls). It cannot predict gas costs for loops that have never been executed on-chain—the tool analyzes bytecode but cannot validate against actual transaction data. It cannot account for compiler optimizations that unroll or rewrite loops—the detected loop patterns may differ from the original source code. It cannot estimate gas costs for nested or complex loops with variable execution paths—the tool simplifies loop analysis to the detected body and does not model conditional execution within loops. It cannot account for state changes that affect future loop iterations (e.g., storage writes that change loop bounds). It cannot simulate actual EVM execution with specific input values. The tool's gas estimates are approximations and may not reflect actual gas costs due to network conditions, gas price fluctuations, or EVM implementation differences. It cannot analyze contracts with no bytecode or contracts compiled with non-standard compilers.

PLEASE NOTE

This tool only supports EVM-compatible blockchains (Ethereum, Polygon, BSC, Avalanche C-Chain, Optimism, Arbitrum, and their testnets). Solana, Tron, Starknet, SUI, TON, Aptos, Bitcoin, Cosmos, and XRP are not supported. The tool is free, open-source, requires no API keys, and uses the wallet's native provider for all read operations. Gas estimates are approximate and should be validated with actual simulation tools before relying on them for production decisions.