Habit calculators and planners

Small tools with a real calculation behind them. Nothing you enter leaves your browser.

• Habit formation calculator

  This habit formation calculator turns research into calendar dates. In a 2010 study of 96 people at University College London, reaching a plateau of automaticity took between 18 and 254 days, with a median of 66 days. Enter your start day to see those dates.

• Habit streak planner

  Divide your goal in days by the number of days you will realistically do the habit each week, then multiply by seven for calendar days. For example, 100 completed days at five days a week takes 140 calendar days. This planner does the arithmetic and gives you a finish date.

• 1% better every day: the exact arithmetic, with a calculator

  Getting 1% better every day compounds to about 2.7 times after 100 days and about 37.8 times after 365 days, because 1.01 to the power of 365 is 37.7834. Declining by 1 percent daily leaves about 0.0255. This is arithmetic about compounding, not a forecast of how people actually improve.