eth_feeHistory

eth_feeHistory looks backward across a window of recent BNB Smart Chain blocks and returns each block's base fee (paid in BNB), its gas-used ratio, and priority-fee samples at the percentiles you request. With BSC sealing a block roughly every three seconds under PoSA, even a few dozen blocks captures a fresh, fine-grained fee picture. Call https://bsc.therpc.io/YOUR_API_KEY at chain ID 56, and the data becomes the raw input for an EIP-1559 fee strategy that picks sensible maxFeePerGas and tip values.

Use cases

Build a fee estimator that reads recent percentile rewards to set maxFeePerGas and maxPriorityFeePerGas for a BNB transaction.
Render a fee-trend chart in a wallet or in a bscscan.com-style explorer view.
Watch gasUsedRatio climb toward 1.0 to detect BSC congestion during busy PancakeSwap windows.
Drive MEV-aware bidding by inspecting how high the upper reward percentiles run block to block.

Parameters

#	Name	Type	Required	Description
1	`blockCount`	string \| number	Yes	Number of blocks to include in the history window. Most providers cap this at 1024.
2	`newestBlock`	string	Yes	The most recent block to include in the window.Default: `latest`
3	`rewardPercentiles`	number[]	No	Array of percentile values (0–100) at which to sample priority fees from each block. Pass an empty array to omit reward data.

Response

Type	Description
object	Object with: `oldestBlock` (hex, starting block of the window), `baseFeePerGas` (array of hex wei — one per block plus the next predicted value), `gasUsedRatio` (array of floats 0–1 per block), `reward` (array of arrays — per-block percentile priority fees in hex wei; only present when `rewardPercen

Example request

1curl https://bsc.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 BNB Smart Chain playground.

Errors & troubleshooting

Code	Message	Cause
`-32602`	`invalid argument`	blockCount is 0, out of range, or rewardPercentiles contains values outside 0–100.
`-32000`	`block not found`	`newestBlock` references a block that does not exist on this node.

Common pitfalls

The baseFeePerGas array carries one extra trailing entry: the node's forecast for the next BSC block, which has not been sealed yet — do not mistake it for a confirmed fee.
Against a network or node that predates EIP-1559 support, the call errors out or omits the fee fields entirely; guard for that path.
A large blockCount returns a hefty payload, so cap the window at roughly 100–200 blocks per request and page through longer ranges.

Supported networks

Mainnet — Chain ID: 56
Testnet — Chain ID: 97