Date & Time
Calculate calendar dates, workdays, elapsed intervals, high-precision stopwatch laps, and session tally counts. All tools navigate leap years and time zones accurately, running 100% client-side with zero tracking or uploads.
All Date & Time Tools (12)
Date Calculator – Add or Subtract Calendar Days
Add or subtract days, weeks, months, and years from any starting date with precise calendar and leap year adjustments.
Days Between Dates Calculator – Date Difference
Calculate total calendar days, business workdays, weekend days, and full duration between any two dates.
Stopwatch – Online Millisecond Accurate Stopwatch
Accurate online stopwatch with millisecond precision, lap tracking, split times, and background tab accuracy.
Tally Counter – Multi-Item Click Counter Online
Versatile click counter supporting multiple counters, customizable increments, decrements, and session persistence.
Business Days Calculator (Working Days & Holiday Exclusion)
Count working days between dates or add business days to a starting date with custom weekend and holiday exclusions.
Time Duration Calculator (Hours, Days & Workdays)
Calculate the exact elapsed time duration between two dates and times, with business days and total hour conversions.
Unix Timestamp Converter: Epoch Seconds to Date & UTC
Convert Unix epoch timestamps to UTC ISO dates, local time, and relative intervals.
Unix Timestamp Converter
Convert Unix epoch seconds and milliseconds to human-readable dates and back.
Work Hours & Timesheet Calculator
Calculate daily work hours, unpaid lunch breaks, overtime, and gross payroll earnings.
Online Stopwatch with Split Laps
Precise digital stopwatch with millisecond accuracy and multi-lap split time recording.
World Clock Meeting Planner
Coordinate global meetings across multiple time zones with business hour compatibility grids.
Retirement Countdown Calculator
Count down remaining years, months, days, and working hours until your target retirement date.
Calendar Mathematics & Chronological Precision
Chronological calculations are deceptively complex. Variations in monthly day counts, quadrennial leap year rules, daylight saving shifts, and statutory business holidays make mental date arithmetic prone to significant human error.
Toolzy's Date & Time utilities leverage the ISO 8601 extended calendar standard and local browser high-resolution time APIs (window.performance.now). Whether you are projecting contract deadlines, calculating statute of limitations expiration, tracking business day turnarounds excluding weekends, or timing lab sprints, our tools provide exact chronological precision.
Because all operations execute locally, no personal calendar appointments, project timelines, or session tallies are ever transmitted across the internet.
Key Formulas & Mathematical Standards
Precision algorithms and verified standards powering our date & time
Calendar Day Difference
Computes total integer days between two epoch timestamps taking into account leap seconds.
Business Working Days
Filters out non-working Saturday and Sunday intervals across the span of the calendar range.
Gregorian Leap Year Condition
Official Gregorian calendar leap year rule accounting for the 400-year cycle century exception.
Who Uses Our Date & Time?
Frequently Asked Questions
Common questions about using our date & time
Do the date calculators account for leap years?▼
Yes, all calculations strictly follow the Gregorian calendar standard, including leap years (such as 2024, 2028) and century rules.
Can the business day calculator exclude specific holidays?▼
Yes, the tool allows you to filter standard weekend days and account for custom non-working holidays to give you an accurate commercial turnaround window.
How accurate is the online stopwatch?▼
Our stopwatch uses the browser's performance.now() API, which provides sub-millisecond hardware clock resolution rather than standard lower-precision timer ticks.
Will my tally counter reset if I accidentally refresh the page?▼
The tally counter preserves state in your browser's local session storage so your counts remain intact even across accidental page reloads.
Explore Other Categories
Discover more fast, browser-based utilities across our specialized collections
Unit Converters
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Math & Education
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Home & Construction
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Finance
Discount savings, markup, profit margins, CD returns & overtime pay.