eth_getUncleCountByBlockNumber

eth_getUncleCountByBlockNumber returns, as a hex string, the number of uncle blocks referenced by the block at a given height or block tag (latest, earliest, safe, finalized, and so on). On Polygon — the PoS network whose gas token is MATIC, served at https://polygon.therpc.io/YOUR_API_KEY (chain ID 137, 0x89) — the answer is always "0x0", since its Bor/Heimdall consensus with L1 checkpoints does not fork into uncles. The method is the height-addressed counterpart of eth_getUncleCountByBlockHash and is kept for Ethereum JSON-RPC compatibility.

Use cases

• Walk a sequential range of block numbers to compute an uncle rate over time; on Polygon every height returns "0x0", so the computed rate is zero — a direct reflection of its forkless PoS design.
• Use it as a quick precheck before requesting uncle details with eth_getUncleByBlockNumberAndIndex; since Polygon's count is always "0x0", you can skip that follow-up entirely.

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_getUncleCountByBlockNumber",
7    "params": ["latest"],
8    "id": 1
9  }'

Try it live in the Polygon playground.

Errors & troubleshooting

Common pitfalls

• On Polygon's PoS chain the result is "0x0" regardless of which block or tag you pass, so do not write branching logic that assumes a height could ever carry uncles here.
• The value comes back as a hex string ("0x0"), not a number — convert it (e.g. parseInt(result, 16)) before doing any numeric comparison or arithmetic.

Supported networks

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

See also

• eth_getUncleByBlockNumberAndIndex
• eth_getUncleCountByBlockHash
• eth_getBlockByNumber

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_getUncleCountByBlockNumber","params":[""]}'