Checking if a transaction is going to require the 0.01BTC transaction fee.

[dgamer5000]

There doesn't seem to be an API Call that can do this. At least, I can't find one. Yet, the bitcoin client is able to do it. Any idea how I can do it?

[theymos]

The selected coins are randomized with each send, so an estimate wouldn't be entirely reliable. Someone recently published a patch that added "prepared" transactions, though.

Generally, if you're sending more than a few BTC and the amount you're sending is much less than the total amount of BTC in your wallet, there will be no required fee.

[Gavin Andresen]

What theymos said.  There's another thread about this, too, and I'll ask here what I asked there:  what is the use case for an 'estimate transaction fee' function? What if the estimate is wrong, what would your application do?

[Pieter Wuille]

See the 3rd commit here: https://github.com/bitcoin/bitcoin/pull/289

It introduces RPC calls to prepare a transaction, inspect it, and then choose to send or cancel it.

[Dude65535]

The estimate being wrong would not be a big problem if there were a way to resend an existing transaction with a fee (or a bigger fee) attached. For the gui I would think the right place for such a command would either be right clicking the 0 confirmation transaction or in the window brought up by double clicking the transaction.

[redshark1802]

Wouldn't it be possible to send X and the client automatically calculates the fees(Y) for it?
Resulting in X(new) = X(old)-Y?

regards, redshark1802