I currently have BTC 0.38 in a wallet on a computer and I want to transfer all those Bitcoins on another machine.

As I have the Bitcoins on a relatively new address (it has received 1 payment and also some Bitcoins through the move API call), it wouldn't let me transfer the Bitcoins without paying a fee.

I don't want to pay this fee, as it is pretty high for what I'm trying to transfer.

Do I just have to wait some time before spending them again to be able to do so without this fee? Or should I do something else?

  • Do you have a number of very small unspent transactions? If so, you will be required to pay a fee as a result. Dec 15, 2013 at 19:00
  • I would also like to know the answer to do this. Back in the day, bitcoin transaction fees were optional. I don't know if this is coded into the bitcoin network or simply the client.
    – mosca1337
    Dec 15, 2013 at 19:58

1 Answer 1


The fact that you need to pay a transaction or not is determined by the priority of a transaction.

Currently the priority of a transaction is calculated with this formula.

priority = sum(input_value_in_base_units * input_age)/size_in_bytes

The minimum transaction priority for free transactions is actually 57,600,000.

Because you have all the coins in the same transaction output and I guess you will send them to one unique address the transaction size will be about 250 bytes. You have:

min_free_input_age = (min_priority_for_free_tx * size_in_bytes)/input_value_in_base_units
min_free_input_age = (57600000 * 250) / 38000000
min_free_input_age = ~378

So you have to wait 378 blocks (~3 days) before you can spend your coins without TX fee. But note that once sent it will probably take 2 or 3 days more before the transaction will be added in a block.

Please correct me if there is a calculation error.

  • I have all of them on an unique address, but I originally received them on 3 separate addresses. Does that matter? And if it does not: why doesn't the client transfer all the Bitcoins on to a single address before sending them? Dec 16, 2013 at 15:47
  • I've written the answer too fast. The import thing is not to have them on the same address but in the same transaction output.
    – Jan Moritz
    May 21, 2014 at 19:08

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