eth_feeHistory

eth_feeHistory returns historical base fees, gas-used ratios, and priority-fee percentiles for a window of recent Polygon PoS blocks. Polygon implements EIP-1559, so fees are paid in MATIC as a base fee plus a priority tip, and this method gives you the raw data to estimate both. Because Polygon produces a block roughly every 2 seconds, a window of even a few hundred blocks still only spans minutes — ideal for a responsive fee oracle. Query https://polygon.therpc.io/YOUR_API_KEY (chain ID 137, 0x89) with a block count, a newest block, and the percentiles you want sampled.

Use cases

• Build a MATIC fee estimator that derives maxFeePerGas and maxPriorityFeePerGas from recent percentile data for type-2 Polygon transactions.
• Render a gas-fee trend chart in a Polygon wallet or explorer from the per-block base fees.
• Detect Polygon congestion — for instance a burst of QuickSwap or Polymarket activity — by watching gasUsedRatio climb toward 1.
• Implement MEV-aware tipping by analysing the high-percentile reward values to land in competitive blocks.

Parameters

Response

Example request

1curl https://polygon.therpc.io/YOUR_API_KEY \
2  -X POST \
3  -H "Content-Type: application/json" \
4  -d '{
5    "jsonrpc": "2.0",
6    "method": "eth_feeHistory",
7    "params": [
8        4,
9        "latest",
10        [
11          25,
12          50,
13          75
14        ]
15      ],
16    "id": 1
17  }'

Try it live in the Polygon playground.

Errors & troubleshooting

Common pitfalls

• The baseFeePerGas array has one more element than the block window: the last entry is the node's prediction for the next Polygon block, not a confirmed value.
• Polygon does implement EIP-1559, so fee fields are present — but if you reuse this code against a non-1559 chain it will error or omit the base-fee data.
• A large blockCount produces a big response; most providers cap it at 1024, and capping yourself at 100–200 blocks per call keeps payloads small and oracle updates fast.

Supported networks

• Mainnet — Chain ID: 137
• Amoy — Chain ID: 80002

See also

• eth_gasPrice
• eth_estimateGas
• eth_maxPriorityFeePerGas

1curl https://polygon.therpc.io/YOUR_API_KEY \
2  -X POST \
3  -H 'Content-Type: application/json' \
4  -d '{"jsonrpc":"2.0","id":1,"method":"eth_feeHistory","params":["4","latest",[25,50,75]]}'