average cycle length 🤔

A glimpse of Heaven 💛 • 🩷💙🩷💙

Normally my average cycle length is 25 days but my last cycle was 27 (AF was 2 days late in November) so when using calculators (ex: ovulation or pregnancy test calculators) should I use my average length of 25 days or my most recent which is 27 days in November?