How Dynamic Transactions Work?

[roy]

I'm using Copay Wallet app and there is three options for transaction fees:

Priority: 0.002213 BTC/kiB
Normal: 0.000152 BTC/kiB
Economy: 0.000053 BTC/kIB

How do I know how much will I pay for transferring some coins?

[CryptAxe]

Copay allows you to choose your transaction fee. Transaction fees are an optional (but basically required, for a reasonably fast transaction) fee that is paid directly to the Bitcoin miners that secure the network. You can select any of the three options copay provides, with the idea that paying more causes your transaction to be confirmed more quickly on the Bitcoin network.

[roy]

I understand completely what you said. What I asked was how to calculate how much I'm going to spend for a transaction.

What KiB means?

For what I understand, the fee is variable in any of the options.

I have the impression that if you're going to send 1BTC from many addresses containing fractions, it can increase considerably because it'll have more information in the transaction (more KB).

[ranochigo]

KiB is kilobyte.

Usually, the client analysies the mempool and attempts to get the information about the average fees. Miners usually include transactions by the fee/kb to utilise the space efficiently. The higher TX fee/kb would get included first. They call the shots so your transactions might not get included no matter how much you pay.

Yes, a higher amount transacted does not mean that the size would be higher. The inputs of a transaction only contains the TXID that the UXTO (Unspent Transaction Output) is in and a script to satisfy the requirement for the output to be used. The output contains integers and scripts that supply the requirements for the UXTO to be valid in the future transactions. This means that a higher number of output and inputs would result in a larger size. Even a 1000BTC TX can be sent without fee and confirm in a timely fashion if the coins aren't moved for a long time and have a small size.

[bitkilo]

I understand completely what you said. What I asked was how to calculate how much I'm going to spend for a transaction.

What KiB means?

For what I understand, the fee is variable in any of the options.

I have the impression that if you're going to send 1BTC from many addresses containing fractions, it can increase considerably because it'll have more information in the transaction (more KB).

Most wallets have multible fee options and i always choose "optimul" or similar.
It is always best to add a fee as the normal rule of thumb is the larger the fee the more incentive the miners have to include your transaction in the next block.

If your dealing with old coins that have sat in your wallet for years then you should get away with sending them with no or very little fee since its the average value-times-age that matters.

This would be a good link to have a look at if you interested in how the network deals with fees:
http://bitcoinfees.com/