The estimatesmartfee RPC estimates the approximate fee per kilobyte needed for a transaction to begin confirmation within conf_target blocks if possible and return the number of blocks for which the estimate is valid.

# estimatesmartfee conf_target ("estimate_mode")

## *bitcoin-cli help estimatesmartfee

estimatesmartfee conf_target ( "estimate_mode" ) Estimates the approximate fee per kilobyte needed for a transaction to begin confirmation within conf_target blocks if possible and return the number of blocks for which the estimate is valid. Uses virtual transaction size as defined in BIP 141 (witness data is discounted). Arguments: 1. conf_target (numeric, required) Confirmation target in blocks (1 - 1008) 2. estimate_mode (string, optional, default="conservative") The fee estimate mode. Whether to return a more conservative estimate which also satisfies a longer history. A conservative estimate potentially returns a higher feerate and is more likely to be sufficient for the desired target, but is not as responsive to short term drops in the prevailing fee market. Must be one of (case insensitive): "unset" "economical" "conservative" Result: { (json object) "feerate" : n, (numeric, optional) estimate fee rate in BTC/kvB (only present if no errors were encountered) "errors" : [ (json array, optional) Errors encountered during processing (if there are any) "str", (string) error ... ], "blocks" : n (numeric) block number where estimate was found The request target will be clamped between 2 and the highest target fee estimation is able to return based on how long it has been running. An error is returned if not enough transactions and blocks have been observed to make an estimate for any number of blocks. } Examples: > bitcoin-cli estimatesmartfee 6 > curl --user myusername --data-binary '{"jsonrpc": "1.0", "id": "curltest", "method": "estimatesmartfee", "params": [6]}' -H 'content-type: text/plain;' http://127.0.0.1:8332/