How often do you have to backup your wallet to ensure you don't lose coins?

[manuel]

Why would you loose coins anyway even if you only backed up your wallet once upon creation?  Isn't it the blockchain that retains all the ownership records of the coins and not the wallet itself?

[Birdy]

the bitcoin-qt client (and maybe others, too) will create new addresses for change (yes, there is change). It will take those from a pregenerated pool, but once those are all used it will generate new ones which aren't in the backup.
As long as your Bitcoins are on old addresses, the backup will have them.

[Barek]

Default size of that pool is 100.

[justusranvier]

Use Armory.

[krishatnet]

I generally back up my wallet every month.

[Barek]

I generally back up my wallet every month.

As long as you don't do more than 100 transactions in a month ...

Oh, yes, another vote for Armory!

[escrow.ms]

I use electrum, just done 2 backups for safety.

[kokojie]

exactly once, if you use blockchain.info and never generate new address.

If you generate new address, then back up after.

[WishIStartedSooner]

When I make new addresses in Blockchain wallet

[mb300sd]

start bitcoin with -keypoolsize=10000

[Lauda]

I never back it up. Never had problems which needed a backup to fix (with anything).

[LiteCoinGuy]

several.

[ralree]

Like other users said, back up your wallet to more than one place.  Using armory is the best option, since you can recreate all the addresses from the master seed, so you just have to print a single page of paper.  If you want to use vanity addresses, make sure to print each one on paper.  I also encrypt mine with PGP and put them in 'the cloud.'  This way, if my house burns down, I can still recover my BTC.  I switched to using electrum and I like it quite a bit.  I have it store its wallet files in my dropbox folder, so they constantly sync.  I also keep nearly all of my coins on offline wallets which I generate here:

https://www.bitaddress.org

This way, even if I get hacked, there's only going to be a few BTC stolen, not my entire stash.  I recommend more people do the same - offline wallets are fantastic.

[twmz]

I have a cron job that backs up my wallet to Dropbox every 15 minutes...

[Barek]

I have a cron job that backs up my wallet to Dropbox every 15 minutes...

Does Dropbox keep multiple versions? Or will it overwrite a good copy with a corrupt one (incase your local wallet ever gets corrupted)?

[Rluner]

I have a cron job that backs up my wallet to Dropbox every 15 minutes...

Does Dropbox keep multiple versions? Or will it overwrite a good copy with a corrupt one (incase your local wallet ever gets corrupted)?

I believe it does.

Let's just hope we can trust Dropbox employees with our wallet data.

[Lauda]

I never back it up. Never had problems which needed a backup to fix (with anything).

I don't wear a seat belt. I've never been in a car accident.

This is also correct. I never wear it, and don't plan to.

[manuel]

exactly once, if you use blockchain.info and never generate new address.

If you generate new address, then back up after.

Where does blockchain.info fit in?  Isn't that a web wallet that doesnt' require any backup?

[escrow.ms]

exactly once, if you use blockchain.info and never generate new address.

If you generate new address, then back up after.

Where does blockchain.info fit in?  Isn't that a web wallet that doesnt' require any backup?

No, Blockchain.info requires backup.

[Birdy]

Where does blockchain.info fit in?  Isn't that a web wallet that doesnt' require any backup?

Nothing requires a backup, but you should have a backup.
Actually blockchain.info is th only Onlinewallet that gives you the opportunity and responsibility to make one.