Quote from: prezbo on December 08, 2012, 11:22:17 PM

Quote from: 2112 on December 08, 2012, 11:10:58 PM

Quote from: Ascholten on December 08, 2012, 07:51:08 PM

or am I just stuck and paying a BIG fee?

Not if you have a bitcoin-rich uncle. Just meet with him and ask him to use his 1000 BTC wad of cash to mop up the dust in your wallet.

I'm not kidding. You can avoid all fees if you can convince someone to include your small transaction outputs in a single large transaction. It is the total sum transferred that matters.

If my calculation is correct, he would need ~3200 btc*day worth of inputs, so about 100 of 1 month old coins would probably do it. If I had any old coins I would gladly do this for you, but alas I don't.

Let's show our work:

Typical transaction size examples in KB (from blockchain):

A) 1 input/1 output (sending exact balance of one input) = 191 bytes
B) 1 input/2 output (sending money from single input with some change) = 258 bytes
C) 2 input/1 output (consolidating two address balances to one output) = 404 bytes
D) 12 input/2 output (sending from many inputs with change) = 1851 bytes
E) 34 input/1 output (consolidating 34 inputs to one output) = 3400 bytes
F) 128 input/2 output (sending with a dice-spammed wallet) = 22935 bytes

Calculated fee for last transaction in list = 23k * .0005 = 0.0115 regardless of actual BTC amount sent (actual transaction was 0.013 BTC fee).

Code:

priority = sum(input_value_in_base_units * input_age)/size_in_bytes
minimum priority to avoid the enforced limit = above 57,600,000

So if transaction example B was a 20 BTC input with 144 confirmations (1 day old):
priority = ( 2,000,000,000 * 144 ) / 258 = priority 1,116,279,060 = free OK

If transaction example F input was 20 BTC, one day old, plus 127 satoshispams, one day old:
priority = { ( 2,000,000,000 * 144 ) + ( 1 * 144 ) + ( 1 * 144 ) + ( 1 * 144 ) .... } / 22935
priority = { (288000000000) + (18288) } / 22935
priority = 12,557,234 < 57,600,000

That transaction priority would be about one-fifth the size needed for free priority, either we can wait five days instead of one day, or use 100 BTC instead of 20 when adding a "helper balance" to the wallet.

Note above that the age of the small-BTC spam inputs have near zero effect on the priority, only their additional size.
Double the spam inputs, you only double the size, and double the age or balance required by a big helper balance when attempting to empty wallet for free.