To count days: the first day is the day after the amount is due and the last day is the day which the payment is received or the day of judgment.
Days are available on a table of days.
Be sure to know whether there is a leap year in the year(s) you are calculating interest on for this will affect the calculation of pre and post judgment interest.
When using the chart minus 1 before making the calculation for days.
Claim is on March 31, 2012 and the judgment day is April 14, 2012. Therefore your first day in your calculation is April 1, 2012 and your last day is April 13, 2012. So 13 days. Post judgment will start on April 14 and end when the money is paid. The money is paid on the 5 June 2012.
Calculate as of the day the cause of action arose to the day before judgment
2000 x 0.03 x (13/365) = $2.14
Post Judgment Interest:
Calculate post judgment interest from the day of judgment up to and including the payment date.
April 14, 2012 to June 5, 2012 = 53 days
2002.14 x 0.03 x (53/365)
= 60.0642 x 0.145
= $ 8.72