Bitcoin Mempool Visualizer

See inside Bitcoin's waiting room.
Live mempool data. Recommended fees. Fee histogram. Updated every 30 seconds.

The Bitcoin mempool is where unconfirmed transactions wait to be included in a block. When the mempool is congested, fees rise as users compete for limited block space. This visualizer shows you real-time mempool conditions so you can time your transactions for the lowest possible fees.

Live Mempool Status

Fetching mempool data…

What Is the Bitcoin Mempool?

The mempool (short for "memory pool") is a temporary storage area where valid but unconfirmed Bitcoin transactions wait before being included in a block. Think of it as a waiting room: when you broadcast a transaction, it enters the mempool and stays there until a miner picks it up and adds it to a block.

Each Bitcoin node maintains its own mempool. When the network is busy, the mempool grows as transactions pile up faster than miners can process them. During quiet periods, the mempool may nearly empty out, and even low-fee transactions get confirmed quickly.

Why miners care about the mempool

Miners select the highest-fee transactions from the mempool to maximize their revenue. A congested mempool means higher fees for miners — and the fee histogram above shows exactly how much fee income is waiting to be claimed.

How Fees Are Prioritized

Bitcoin miners have limited block space (approximately 4 MB per block, or about 1 vMB of weight). When more transactions are waiting than can fit in a block, miners naturally pick the ones paying the highest fee per virtual byte (sat/vB). This creates a fee market:

High Congestion

When the mempool is large (100+ MB), fees spike. Only transactions paying premium fees get confirmed quickly. Low-fee transactions may wait hours or even days.

Low Congestion

When the mempool is small (under 5 MB), even minimum-fee transactions get confirmed in the next block. This is the ideal time to send transactions at the lowest cost.

Reading the Fee Histogram

The fee histogram shows how much transaction data (measured in virtual megabytes) is waiting at each fee rate. Taller bars at high fee rates mean heavy congestion and expensive transactions. When most of the volume sits at low fee rates, the network is calm and affordable.

As a sender, you want your fee to be competitive with the current "front of the line." The recommended fees section above does this calculation for you — just pick the speed tier that matches your urgency. As a miner, a loaded histogram means rich blocks full of high-fee transactions waiting to be mined.

Frequently Asked Questions

What is a sat/vB and how does it determine my fee?

Sat/vB means "satoshis per virtual byte." It's the fee rate that determines how quickly your transaction gets confirmed. A typical Bitcoin transaction is about 140 vBytes. At 10 sat/vB, the total fee would be 1,400 satoshis (~$1 at current prices). Higher sat/vB = faster confirmation but higher cost.

When is the cheapest time to send a Bitcoin transaction?

Fees are generally lowest on weekends (especially Sunday mornings UTC) and during low-activity periods in the US and European time zones. Watch the mempool size above — when it's under 5 MB and the minimum fee is 1-2 sat/vB, that's an ideal time to send. During NFT mints, token launches, or market volatility, fees can spike 10-50x.

How does the mempool affect miners?

A full mempool is great for miners. When many transactions are competing for block space, fees increase, boosting miner revenue beyond the base block reward. During periods of high congestion, transaction fees can sometimes equal or exceed the 3.125 BTC block reward. This fee income is increasingly important as block rewards halve every four years.

My transaction is stuck. What can I do?

If your transaction is unconfirmed for a long time, you have several options: (1) Wait — if the mempool clears, even low-fee transactions eventually confirm. (2) RBF (Replace-By-Fee) — if your wallet enabled RBF, you can rebroadcast with a higher fee. (3) CPFP (Child-Pays-For-Parent) — send a new transaction spending the unconfirmed output with a high enough fee to incentivize miners to confirm both. Most modern wallets support RBF.

How big is the Bitcoin mempool right now?

Check the "Mempool Size" card at the top of this page for the current size in megabytes. A mempool under 5 MB usually means low fees and quick confirmations. Between 5-50 MB is moderate. Over 100 MB indicates significant congestion. The data updates every 30 seconds using the mempool.space API.

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