Test any year for leap status with the full Gregorian rule — divisible by 4, except centuries unless divisible by 400. Settle the 1900 vs 2000 debate instantly — free, runs locally.
Content reviewed October 2026 · About Toolzum
Compute test percentages and grades from correct/total with curve options. Turn 42/50 into 84% (B) instantly — free, local, no signup.
Find the weekday for any Gregorian date — plan anniversaries, verify old records, settle bets. Check what day you were born in seconds — free, no signup, runs locally.
Measure the exact gap between two dates in days, weeks, and months — tenures, ages, project spans. A 3-year job stint reads 1,096 days instantly — free, no signup, runs locally.
Read any PDF's metadata instantly — page count, size, author, creation date, encryption status. Verify a download before opening fully — local parsing, free, no signup.
Test JavaScript template literals live — ${} interpolation, nesting, and escaping, evaluated instantly with instant error highlighting.
1900 is not (century not divisible by 400); 2000 is (divisible by 400). The rule: divisible by 4, except century years, except centuries divisible by 400 — the tool applies all three clauses.
Earth's orbit is 365.2422 days, not 365.25 — the century skip corrects the 11-minute yearly drift. Without it, calendars would slide a full day every 128 years.
For 29 February birthdays: the tool confirms which years actually contain the date, so milestone parties land on real calendar days.
No — the check runs entirely in your browser. Nothing leaves your device.
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