Everyday
Tips, discounts, and quick everyday math.
Tip Calculator
Tip amount, total bill, and amount per person.
Discount / Sale Price Calculator
Stacked discounts, total savings, and sales tax.
Age Calculator
Exact age in years, months, and days from a date of birth.
Date Difference Calculator
Days, weeks, months, and years between two dates.
Tip Calculator
This calculator applies your chosen percentage directly to the bill amount to get the tip, then adds that to the bill for the total, and divides the total evenly across however many people you enter. It doesn't try to round to "nice" per-person amounts, so if you need clean bills or coins, round up slightly and treat the difference as a bit of extra tip. The quick-select buttons are just shortcuts for common rates (15/18/20/25%) — you can still type any custom percentage.
Discount / Sale Price Calculator
Multiple discounts here stack multiplicatively, not by adding the percentages together: a 20% discount followed by an additional 10% off multiplies the price by 0.8 and then by 0.9, which comes out to less savings than a flat 30% off. This is how "extra X% off already-reduced items" actually works at most stores, so it's worth checking each discount is meant to apply to the already-discounted price rather than the original. Sales tax, if entered, is calculated on the final discounted price rather than the original sticker price.
Age Calculator
Your age breakdown is calculated calendar-aware, not by dividing total days by 365: it counts full elapsed years, then full elapsed months within the current year, then the leftover days, borrowing from the previous month's actual length (28-31 days) whenever the day-of-month hasn't been reached yet. That's why the years/months/days figure matches how people naturally describe their age, while the "total days alive" figure is a separate straight day-count between the two dates. The next-birthday countdown simply looks at this year's birthday date and rolls to next year if it's already passed.
Date Difference Calculator
Total days is a straight count between your two dates, while months and years are approximations derived from calendar months and a 365.25-day average year, so don't expect the years figure to line up exactly with a birthday-style breakdown. If you enter an end date earlier than the start date, the calculator swaps them automatically and tells you it did so, rather than showing a negative result. The optional weekday-only count walks day by day and excludes every Saturday and Sunday in the range, which is handy for estimating business-day timelines.