<p><a href="https://en.bitcoin.it/wiki/Key_pool" rel="nofollow">Every 100 transactions</a>, counting both sending and receiving. For receiving, you can treat multiple transactions to the same address as a single transaction.</p>

<p>This ensures that you don't lose any bitcoins if, for example, your hard drive crashes.</p>

<p>The option <code>keypool</code> in Bitcoin-Qt client adjusts this.</p>

CC BY-SA 3.0
2013-04-19T07:04:59.800Z
2013-04-19T07:04:59.800Z
Nick ODell
<p>You're never <strong>obligated</strong> to back up your wallet. It is something you do to protect yourself.</p>

<p>You do not need to backup your wallet to prevent from double spending (you spend BTC, loose your wallet, restore from an old wallet and try to spend the same coin). The protocol will stop that from happening because the transfer exists in the block chain.</p>

<p>However, you do need to back up your wallet to know what you have to spend. Without a current wallet the protocol won't know that you own a BTC and that you can spend it.</p>

<p>It is impossible (without a lot of computing power) to double spend BTC. Without your wallet you won't know what you have to spend. You can loose Bitcoins forever just like you can loose cash forever.</p>

CC BY-SA 3.0
2013-04-19T07:00:43.513Z
This is all true but doesn't answer the question.
Nick ODell
CC BY-SA 3.0
2013-04-19T06:50:24.053Z
2013-04-19T06:50:24.053Z
Will
<p>Is it obligatory to backup <code>wallet.dat</code> after each outgoing transfer?</p>

<p>I understand it is, but not after each incoming transfer.</p>

CC BY-SA 3.0
2013-04-19T13:40:31.990Z
This question has already been asked and answered; see [How should you backup your wallet?](http://bitcoin.stackexchange.com/questions/746/how-should-you-backup-your-wallet/).
gosuto
<wallet><client><bitcoin-core><wallet.dat>
When do I have to backup wallet.dat?
Michał Tajchert
# When do I have to backup wallet.dat?

(Asked by: username_0 on 2013-04-19)

Is it obligatory to backup `wallet.dat` after each outgoing transfer?

I understand it is, but not after each incoming transfer.

**Tags:** wallet, client, bitcoin-core, wallet.dat

> **Comments:**
> **username_1**: This question has already been asked and answered; see [How should you backup your wallet?](http://bitcoin.stackexchange.com/questions/746/how-should-you-backup-your-wallet/).  

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## 2 answers

### Answer by username_2 on 2013-04-19. Score: 2 | Accepted answer

[Every 100 transactions](https://en.bitcoin.it/wiki/Key_pool), counting both sending and receiving. For receiving, you can treat multiple transactions to the same address as a single transaction.

This ensures that you don't lose any bitcoins if, for example, your hard drive crashes.

The option `keypool` in Bitcoin-Qt client adjusts this.


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### Answer by username_3 on 2013-04-19. Score: -2

You're never **obligated** to back up your wallet. It is something you do to protect yourself.

You do not need to backup your wallet to prevent from double spending (you spend BTC, loose your wallet, restore from an old wallet and try to spend the same coin). The protocol username_3 stop that from happening because the transfer exists in the block chain.

However, you do need to back up your wallet to know what you have to spend. Without a current wallet the protocol won't know that you own a BTC and that you can spend it.

It is impossible (without a lot of computing power) to double spend BTC. Without your wallet you won't know what you have to spend. You can loose Bitcoins forever just like you can loose cash forever.

> **Comments:**
> **username_2**: This is all true but doesn't answer the question.  

---

