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Bitcoin Mempool Fee Heatmap

Live sat/vB fee tiers, the next projected blocks colour-coded by fee rate, and the mempool's depth by fee band — so you can pick the right fee for your next on-chain send and know whether to broadcast now or wait.

Reading the live mempool…

How to use this

Bitcoin fees are paid per virtual byte (sat/vB), and miners fill blocks with the highest-paying transactions first. So the only number that matters for speed is your fee rate, not the total fee. The upcoming-blocks heatmap shows the blocks miners are likely to mine next — block 1 in about ten minutes, block 2 in twenty, and so on — coloured green (cheap) to red (expensive) by each block's median fee. Pay at least a given block's rate and you should land in it.

The depth ladder shows how much transaction weight is queued at each fee band. When the high-fee bands are nearly empty, paying a few sat/vB jumps you to the front. When they're stacked deep, you're competing with a lot of other urgent transactions and the price of speed rises.

Don't overpay

Most wallets default to "fast" and quietly overpay. If the next-block rate is in the single digits, there is essentially nothing to gain from paying more — and if it's elevated but your payment isn't urgent, waiting usually works: outside of sustained inscription / Runes waves, fee spikes have historically drained within days. Best practice is to send with RBF (replace-by-fee) enabled, start at a modest rate, and bump it later only if confirmation is taking too long — rather than burning sats up front. For the full mechanics of the mempool and fee market, see the mempool explainer.

Frequently asked questions

What is a sat/vB fee and why does it matter?
Bitcoin transaction fees are paid per virtual byte (vByte), measured in satoshis per vByte (sat/vB). Miners pick the highest-paying transactions first, so the fee rate — not the total fee — decides how quickly you confirm. A small, efficient transaction at a high sat/vB confirms faster than a large one paying a big total at a low rate. This heatmap shows the sat/vB you need for each confirmation target.
How do I read the projected-blocks heatmap?
Each cell is a block that miners are likely to mine next, roughly ten minutes apart — block 1 is the next ~10 minutes, block 2 the next ~20, and so on. The colour runs green (cheap) to red (expensive) by the block's median fee. To confirm in block N, pay at least the fee rate shown for that block. If you're not in a hurry, aim for a later, greener block and pay less.
What is the mempool backlog in blocks?
The mempool is the queue of unconfirmed transactions each node holds. Its size is measured in virtual bytes; since a block holds roughly one million vBytes, dividing the mempool vsize by that gives the backlog in "blocks" — how many blocks it would take to clear the current queue if no new transactions arrived. A few blocks means the network is quiet; dozens of blocks of high-fee backlog means real congestion.
Should I send now or wait for lower fees?
If the next-block fee is low (single digits of sat/vB) there's little to gain from waiting. If it's elevated and your transaction isn't time-sensitive, waiting often pays off — fee spikes have historically eased within days unless driven by a sustained inscription or Runes wave. Either way, sending with RBF (replace-by-fee) enabled lets you start low and bump the fee later if it's taking too long, instead of overpaying up front.
Where does the data come from and how fresh is it?
Live from the mempool.space public API — recommended fees, the projected mempool blocks and the full fee histogram. The tool auto-refreshes every 60 seconds and all rendering happens in your browser. Fee estimates are a real-time snapshot and can change from block to block, so always confirm the fee in your own wallet before broadcasting a transaction.
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