Kb of a transaction

[roeylee]

How is it calculated? Can I control it?

[MrBig]

How is it calculated? Can I control it?

I think it's about 180 bytes per input and 34 bytes per output, plus another 10 bytes. Just add all the inputs and outputs plus 10 and you should have a rough figure. Transactions sizes can vary from 0.2kb to over 1kb.

[dragone]

I dont think you can, if are you trying to void from the btc fee if I`m guessing correctly.

Everyone has to pay. Its anything less then .1 = lower priority

[BunsenBurner]

How is it calculated? Can I control it?

I think it's about 180 bytes per input and 34 bytes per output, plus another 10 bytes. Just add all the inputs and outputs plus 10 and you should have a rough figure.

Yup. http://bitcoin.stackexchange.com/questions/1195/how-to-calculate-transaction-size-before-sending

You can check the number of inputs and pick the inputs yourself if your wallet has a coin control feature (such as qt 0.9.0+).

[roeylee]

Can I send to multiple addresses in one transaction? How?

[BunsenBurner]

Can I send to multiple addresses in one transaction? How?

Yup, you can.
Which wallet client are you using? Bitcoin Core (Bitcoin-qt)? Electrum? Armory? Blockchain.info?

[roeylee]

Can I send to multiple addresses in one transaction? How?

Yup, you can.
Which wallet client are you using? Bitcoin Core (Bitcoin-qt)? Electrum? Armory? Blockchain.info?

Bitcoin Wallet on my Android

[Harley997]

How is it calculated? Can I control it?

You can control it by spending a smaller number of inputs and by having a smaller number of outputs in your TX.

The ultimate way to have this happen is to not receive irregular amounts to your address (if you can control this). It is generally best to receive round numbers when receiving BTC (for examples multiples of .01).

[DeathAndTaxes]

How is it calculated? Can I control it?

I think it's about 180 bytes per input and 34 bytes per output, plus another 10 bytes. Just add all the inputs and outputs plus 10 and you should have a rough figure.

147 bytes for compressed keys.  Always use compressed keys to save space.   Most wallets by default create compressed keys.  If your wallet doesn't then yell at them.

[bryant.coleman]

Everyone has to pay. Its anything less then .1 = lower priority

Everything less than BTC0.0001 is low priority. But that said, I am seeing a lot of transactions being done with fees ranging from BTC0.00001 to BTC0.00005. May take a while to confirm, but eventually they will, unlike those unpaid transactions. 

[Coef]

Everyone has to pay. Its anything less then .1 = lower priority

Everything less than BTC0.0001 is low priority. But that said, I am seeing a lot of transactions being done with fees ranging from BTC0.00001 to BTC0.00005. May take a while to confirm, but eventually they will, unlike those unpaid transactions. 

IIRC, tx with fee lower than 0.0001 per KB is treated like tx with no fee attached by most of the mining pools, is it true? 

[Harley997]

Everyone has to pay. Its anything less then .1 = lower priority

Everything less than BTC0.0001 is low priority. But that said, I am seeing a lot of transactions being done with fees ranging from BTC0.00001 to BTC0.00005. May take a while to confirm, but eventually they will, unlike those unpaid transactions. 

IIRC, tx with fee lower than 0.0001 per KB is treated like tx with no fee attached by most of the mining pools, is it true? 

Generally speaking yes, however sending something as a fee does have it's advantages, it would act as a "tip" to the miners.