Understanding Bitcoin Transaction Fees and the Mempool: How Not to Overpay

Short answer: You pay bitcoin transaction fees to the miner who writes your transaction into a block. They don't depend on the amount, but on how much space your transaction takes up in the block and on how many others are waiting at the moment. That queue is called the mempool. On Nov 13, 2026, a simple transaction cost less than 10 cents.

You send bitcoin from the exchange to your own wallet, and the transaction has been stuck on "unconfirmed" for hours. Or your wallet suggests a fee of €15 even though you only want to send €50. Both have the same cause: bitcoin transaction fees follow supply and demand in the mempool. Once you understand that, you rarely overpay and you know what to do when a transaction gets stuck. All figures are as of Nov 13, 2026.

Why does a bitcoin transaction cost a fee?

Roughly every 10 minutes, a miner adds a new block to the blockchain. Every block has a fixed upper limit, in practice room for a few thousand transactions. If more people want to send than fit into the next block, a queue forms.

Whoever wants to get to the front offers more. The miner building the block picks the transactions that pay the most per unit of space. So the fee is not a fixed price that someone sets, but the result of an ongoing auction for space in the next block.

The miner receives the fees on top of the newly created bitcoin. Today they are a small part of its income; in the long run, fees are meant to replace the shrinking reward. How miners work and what they earn is explained in the overview Bitcoin mining explained.

What is the mempool?

The mempool (short for "memory pool") is the waiting room for transactions that have been sent but are not yet in a block. When you press "Send" in your wallet, your transaction goes to bitcoin nodes. Each node checks it and puts it into its mempool. Miners take it from there into the next block.

There are three things you should know about the mempool:

• There is no single mempool. Every node keeps its own. They are usually almost identical, but not quite. With your own bitcoin node, you see your own mempool and estimate fees yourself, without asking someone else's server.
• It is limited. By default, Bitcoin Core keeps at most 300 MB in memory. When it gets full, the transactions with the lowest fee are dropped first, and the minimum fee for new ones rises.
• Waiting transactions expire. If a transaction is still not in a block after 14 days, Bitcoin Core removes it from its mempool by default. The bitcoin then simply stay at your address.

On the morning of Nov 13, 2026, according to mempool.space, around 63’800 transactions were waiting. Together they would have filled about 30 blocks. Almost all of them offered only 0.1 to 0.12 satoshi per vByte and were patiently waiting for a quiet hour.

How to calculate the bitcoin transaction fee

The fee results from two numbers: the size of your transaction and the fee rate.

• Size is measured in vBytes (virtual bytes). It depends on how many inputs and outputs your transaction has and which address type you use.
• The fee rate is given in satoshi per vByte, sat/vB for short. One satoshi is one hundred millionth of a bitcoin.

Fee = size × fee rate. A typical transaction from a modern wallet has one input and two outputs (one to the recipient, one as change back to you) and takes up around 141 vBytes. At 10 sat/vB it therefore costs 1’410 satoshi.

With SegWit, every additional input costs around 68 vBytes. That's why many small amounts in a wallet are more expensive to send than one large one. More on this below under saving.

What does a bitcoin transaction cost today?

On Nov 13, 2026, mempool.space recommended 1 sat/vB for confirmation in the next block and 0.124 sat/vB for "within an hour". The minimum fee that nodes relay has been 0.1 sat/vB since Bitcoin Core 29.1; before that it was 1 sat/vB.

The sats calculator works out how much an amount in satoshi is worth today and at other prices:

How high were fees in the past?

Fees fluctuate strongly, and the peaks always came when many people wanted the same thing at the same time: buying in a bull market, minting inscriptions and tokens on the blockchain or catching the first block at the halving.

Source: mempool.space, median fee rate of the blocks. In 2017 there was hardly any SegWit yet, so one vByte equals one byte.

The record is held by halving block 840’000 on Apr 20, 2024: its fees alone brought the miner 37.6 BTC, twelve times the new reward of 3.125 BTC. Since the start of 2025, on the other hand, blocks have rarely been full, and fees are close to the minimum.

For you this means: low fees are not a permanent state. Plan so that a phase of 50 or 200 sat/vB doesn't force you into an expensive transaction.

Reading the mempool: which fee is the right one?

Most wallets suggest three levels, such as "slow", "medium" and "fast". To do this, they ask a server or your own node how full the mempool is right now. If you want to check yourself, open mempool.space.

How to read the site:

1. Fee recommendation at the top: "Low priority", "Medium priority" and "High priority" are estimates for about an hour, half an hour and the next block.
2. The blocks on the left: these are the next blocks as they would be built from the mempool. Below each is the range of fee rates. If your rate is above the range of the first block, you are likely to be in the next one.
3. Find your transaction: enter the transaction ID from your wallet into the search field. You then see the fee rate, the size and an estimate of when it will be confirmed.

A pattern from the data: in 2023 and 2024, Sunday was on average the cheapest day (median 13 sat/vB compared with 19 sat/vB on Wednesday). You can't rely on it, but if you can wait, you'll often find a quieter hour at the weekend.

Transaction stuck: how to get it out of the mempool

If you chose too low a fee and fees rose afterwards, a transaction can wait for days. There are two ways to speed it up.

1. Bump the fee (RBF, "Replace by Fee"). You send the same transaction again with a higher fee. The new one replaces the old one in the mempool. Since Bitcoin Core 28.0 from October 2024, nodes accept such replacement transactions by default. In wallets such as Sparrow, Electrum or BlueWallet, the function is usually called "Bump fee" or "Increase fee".

2. Follow-up transaction (CPFP, "Child Pays for Parent"). You send the still unconfirmed change onward with a high fee, or the recipient does so with the amount received. A miner can only include the second transaction if it also takes the first. It therefore counts both together. This also works when the sender can no longer change anything, for example with a withdrawal from an exchange.

Saving on bitcoin transaction fees: five ways

You pay the best fee in quiet times. These five habits add up to noticeable savings over the years.

1. No hurry, low level. For transactions to yourself, the slowest level is almost always enough.
2. Use modern addresses. With a SegWit address (bc1q), a simple transaction costs 38% less than with a legacy address starting with 1. Taproot (bc1p) is almost on par. Every current wallet creates them by default. How to set up a wallet is shown in Set up your first wallet.
3. Withdraw less often. Exchanges and savings plan apps often charge a fixed fee for withdrawals, independent of the mempool. If you withdraw less often, you pay it less often. What individual providers charge is in the bitcoin savings plan comparison.
4. Combine small amounts in quiet times. Every input takes up space when you send later. If you have 12 small savings plan withdrawals in your wallet, you should combine them into one of your own addresses when fees are low ("consolidate"). The worked example below shows what that achieves.
5. Small payments via Lightning. For a coffee or small amounts to friends, the blockchain is too expensive as soon as fees rise. The Lightning Network handles such payments for a few satoshi.

What fees mean for bitcoin in the long run

Today the new bitcoin pay for almost all of the network's security. In the 144 blocks up to the morning of Nov 13, 2026, only 3.46 BTC came from fees, against 450 BTC of new reward. That is 0.8% of the miners' income.

Every four years the reward halves, and around the year 2140 it ends completely. Then fees alone have to pay the miners. Whether that will be enough is an open question that is seriously debated in the community. What is clear: low fees are pleasant for you as a user, but for security in the very long run bitcoin needs demand for block space. How the difficulty ensures that blocks still arrive every 10 minutes is explained in the article Difficulty adjustment.

If you want to learn the basics of wallets, backups and transactions in order, you'll find them in the academy under "Understand & secure". The category Mining & Technology collects more articles on mining, nodes and technology.