eth_getBlockTransactionCountByNumber

eth_getBlockTransactionCountByNumber reports how many transactions sit inside a single Ethereum block, identified by its height or by a tag such as latest or finalized. You point it at a block; it answers with one hex number. On Ethereum mainnet (chain ID 1, where block space is paid for in ETH) a validator seals one block every 12-second slot, so this count is a quick read on how busy that slot was. Send the request to https://ethereum.therpc.io/YOUR_API_KEY and you get back the transaction count for the block at the height or tag you named, without pulling down the full block body.

Use cases

• Gauge live congestion by polling the count at latest each slot — a string of fat blocks usually means the EIP-1559 base fee is about to climb.
• Build a per-block fullness series and feed it into your own fee-estimation heuristic alongside eth_feeHistory, since how packed recent blocks were drives the next base fee.
• Walk a range of heights and flag the outliers: near-empty blocks during quiet hours, and the dense ones that spike during an airdrop claim or a popular NFT mint on OpenSea.

Parameters

Response

Example request

1curl https://ethereum.therpc.io/YOUR_API_KEY \
2  -X POST \
3  -H "Content-Type: application/json" \
4  -d '{
5    "jsonrpc": "2.0",
6    "method": "eth_getBlockTransactionCountByNumber",
7    "params": ["latest"],
8    "id": 1
9  }'

Try it live in the Ethereum playground.

Errors & troubleshooting

Common pitfalls

• The pending tag counts the transactions a client currently expects to pack into the next block from the mempool, so two calls a second apart can disagree as new txs arrive and others get included.
• The result is a hex string like 0x9c, not a JS number. Run it through parseInt(value, 16) before you compare or chart it, or your "150" block will sort as the string "0x96".

Supported networks

• Mainnet — Chain ID: 1
• Sepolia — Chain ID: 11155111

See also

• eth_getBlockTransactionCountByHash
• eth_blockNumber
• eth_getBlockByNumber
• eth_getTransactionByBlockNumberAndIndex

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