Coin Selection and Output Design

Coin Selection and Output Recommendations

Inputs:

• Pick single large output that is slightly larger than send value:

  • If possible create 1 - 1 transaction with remainder being a reasonable fee.
  • If change output needed, try to create a round-value output that is at-least 10x the fee.
  • If change would be less than 10x fee, try to find a larger input to spend.

• If large input is more than 2x amount to be spent:

  • Try to create two outputs of identical amount: (i) spend (ii) change.
  • If fee too large create 3 outputs: (i) spend (ii) change (iii) small change round value (at least 10x fee).

Dust

Never spend a dust output that would increase the fee more than the value of the input.

Change

In General: Never create a small change output if it would increase the required fee by more than the output's value.

Privacy: Avoid small outputs in general. Just spend to fee.

Privacy: Try to create change outputs with round-value outputs, adjust fee to have non-round value.