Seven calculators that didn't fit anywhere else — birthdays and dates, time zones, pet ages, Roman numerals and what you'd weigh on the Moon or Mars. All calculations run locally in your browser, with no sign-up.
Which one do I need?
Common questions
Is the ×7 rule for pet ages accurate?
No — it's a rough myth. Dogs and cats age fastest in their first couple of years then slow down, so both the dog age and cat age calculators use size- and lifestage-adjusted formulas, plus epigenetic clock research for dogs, rather than a flat multiplier.
Does the time zone converter handle daylight saving time?
Yes — it accounts for DST in both the source and target zones for the specific date you enter, not just the current offset, since the gap between two zones can change across the year.
How far back do Roman numerals go before the notation breaks down?
Standard notation comfortably covers numbers up to 3,999 (MMMCMXCIX); beyond that, historical convention adds a bar over a numeral to multiply it by 1,000, which the calculator notes if you go past the standard range.