Work out piggy bank savings goal instantly with clear inputs, formula shown and shareable results.
Time to a savings goal is what is left divided by the rate of saving, with monthly extras converted to a weekly equivalent. Showing progress as a percentage matters more than it sounds: visible progress is the single strongest predictor of sticking with a savings plan.
Savings goal
weeks = (goal - saved) / (weekly + monthly extra / 4.348)
At these amounts interest is negligible, but a small matched contribution from a parent teaches the same lesson far more effectively.
Fix the target and the date. A moving goal removes the sense of progress that makes saving work.