# Gas Fee Intelligence Explorer

> Live gas on 7 EVM chains: base fee, tips, trend and the USD cost of transfers and swaps. Pulls eth_feeHistory (last 100 blocks, 10th/50th/90th percentile tips) and eth_gasPrice from Ethereum, Base, Arbitrum, OP Mainnet, Polygon, Avalanche and BNB Chain, prices the native tokens via DefiLlama and shows what a native transfer, ERC-20 transfer and swap cost on each chain — ranked cheapest first, with OP Stack L1 data fees as an upper bound.

Part of usefulweb.site (https://usefulweb.site/). Results are deterministic calculations from the inputs and the listed assumptions; the API returns exactly what the web page shows.

## Use it
- Human interface: https://gasfeeintelligenceexplorer.usefulweb.site/ (interactive tool at https://gasfeeintelligenceexplorer.usefulweb.site/tool)
- JSON API: POST https://gasfeeintelligenceexplorer.usefulweb.site/api/v1/calculate with a JSON object of inputs (schema: https://gasfeeintelligenceexplorer.usefulweb.site/api/v1/tool)
- OpenAPI: https://gasfeeintelligenceexplorer.usefulweb.site/openapi.json
- MCP (Streamable HTTP): https://gasfeeintelligenceexplorer.usefulweb.site/mcp - tool `gas_fee_intelligence_explorer`

## Inputs
- mode (select): Data source
- chains (multiselect): Chains
- blocks (integer): Blocks of fee history
- pasted (textarea): Pasted JSON - {"prices":{"ETH":2400},"chains":{"ethereum":{"feeHistory":{…eth_feeHistory result…},"gasPrice":"0x…","l1FeeUpperBoundWei":{"erc20-transfer":"0x…"}}}}

## Method
- eth_feeHistory(blockCount, "latest", [10, 50, 90]) per chain: base fee per block (the last entry is the next block's base fee) and the 10th/50th/90th percentile priority fee of each block; the tool takes the median of each percentile across blocks.
- Price tiers = next base fee + median p10 (slow) / p50 (standard) / p90 (fast) tip. Chains without a base fee use eth_gasPrice. Trend compares the average base fee of the newest fifth of blocks with the oldest fifth (±15 %).
- Operation costs use typical gas amounts — native transfer 21,000 (exact), ERC-20 transfer ≈ 65,000, DEX swap ≈ 150,000 (estimates; real usage varies by contract and state) — times the standard tier.
- USD: native token prices from the DefiLlama coins API (coingecko:ethereum, polygon-ecosystem-token, avalanche-2, binancecoin).
- L2 data fees: on Base and OP Mainnet the OP Stack GasPriceOracle (0x4200…000F) getL1FeeUpperBound(size) is added as an upper bound using approximate transaction sizes (50 / 120 / 350 bytes unsigned). Arbitrum's L1 component is not included (it is folded into gas used at execution time and needs a per-transaction estimate).