Fee rate is the fee divided by virtual size, in sats per vbyte (sat/vB). It is the number miners sort by. Learn how to calculate and choose one.
The formula
fee rate (sat/vB) = fee (sats) ÷ virtual size (vB)Working it out
A transaction is 141 vB and pays 1,410 sats. Its fee rate is 1,410 ÷ 141 = 10 sat/vB. Another transaction of 282 vB paying 2,000 sats pays more in total but only 7.1 sat/vB, so a miner prefers the first one.
Why miners sort by rate
A block has room for a fixed amount of weight. To earn the most, miners fill it with the highest-paying transactions per unit of space, a bit like packing a suitcase with the most valuable items per centimetre.
Choosing a rate
- Next block: look at current estimates for 1 block.
- Within an hour: a 6-block target is usually much cheaper.
- Whenever: use a low rate and wait for a quiet period, but not below what nodes will relay (see Relay policy and standardness).
Worked example: what will I pay?
A typical native SegWit payment with one input and two outputs is about 141 vB.
| Fee rate | Fee | In BTC |
|---|---|---|
| 1 sat/vB | 141 sats | 0.00000141 |
| 5 sat/vB | 705 sats | 0.00000705 |
| 20 sat/vB | 2,820 sats | 0.0000282 |
Older units you may see
Some tools show sat/byte (the same as sat/vB for legacy transactions) or BTC/kvB, as Bitcoin Core's estimatesmartfee does. To convert BTC/kvB to sat/vB, multiply by 100,000.
Key takeaways
- Fee rate = fee ÷ virtual size, measured in sat/vB.
- Miners prioritise by fee rate, not total fee.
- Pick a target based on how soon you need confirmation.
Common questions
What is a vbyte?
A virtual byte: transaction weight divided by four. It accounts for the SegWit discount.
What fee rate should I use?
Check a current estimate. Fee rates change with demand, from 1 sat/vB on quiet days to much higher when blocks are full.
What is a good fee rate right now?
It changes with demand. Check the MyBitcoinExplorer fee page for our node's current estimates.
Is sat/vB the same as sat/byte?
For legacy transactions yes; for SegWit transactions vbytes account for the witness discount, so sat/vB is the correct measure.