This calculator shows how many interest-free days a credit card purchase actually gets in New Zealand depending on when in your statement cycle you make it, and points you to the best day to time a big buy. The interest-free days a card advertises, often up to 44 or 55, are a maximum, not a guarantee, and the real figure swings widely with timing. The window works like this: purchases sit on the current statement until it closes, then you have a grace period to pay before interest applies, so a purchase made just after the statement date enjoys almost the whole cycle plus the grace period interest free, while one made the day before the statement closes gets only the short grace period. You enter your statement cycle length, the maximum interest-free days your card offers, and how many days after your statement date you are buying, and the calculator returns the interest-free days that purchase will receive, the maximum you could get, and the days you are leaving on the table. Timing a large planned purchase to just after your statement date can give you a month or more of free funding, provided you always pay the closing balance in full by the due date, because carrying any balance usually cancels the interest-free benefit entirely.
Only applies if you pay the closing balance in full by the due date. Carrying a balance usually cancels interest-free days. Estimate only.
The interest-free days for a purchase equal the maximum interest-free days minus how far into the cycle you bought. Buy on the statement date and you get the full maximum; each day later costs you one interest-free day, down to the grace period that applies to a purchase made right before the statement closes.
With a 44 day card and a 30 day cycle, buying 20 days after your statement date gives 44 minus 20, which is 24 interest-free days. Buying the day after the statement would give the full 44, so the timing cost you 20 days.
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