Samourai Wallet Launches Nextblock.is For More Accurate Transaction Fee Estimation The Next Block estimator assesses all the unconfirmed transactions in the mempool, then computes at what miner fee rate a transaction needs to be broadcasted right now for it to be confirmed into the next block. https://www.nobsbitcoin.com/samourai-launches-nextblock-is-for-more-accurate-block-fee-estimation/