About All Time Calculator

All Time Calculator is a free reference tool built for anyone who works with dates, times, schedules, and calendars. Our goal is simple: take calculations that are surprisingly easy to get wrong — business days, overtime hours, time-zone conversions, age, deadlines — and make them instant, accurate, and easy to understand.

What We Build

We maintain more than 40 free online calculators organized into six categories:

Time & Timers — arithmetic, duration, Pomodoro, stopwatch, cooking timers
Date & Lifecycle — age, baby age, birthday, pregnancy due date, retirement countdown
Scheduling & Planning — deadlines, business days, week numbers, time zones, flight planning
Work & Payroll — weekly hours, shift time, overtime, payroll periods, project tracking
Health & Wellness — medication schedules, jet lag recovery, pet feeding
Data & Conversion — Unix timestamps, Julian dates, decimal hours, time unit conversion

Every calculator is built with edge cases in mind: daylight saving transitions, leap years, non-standard work weeks, half-hour time zone offsets, and the quirks that make calendar arithmetic genuinely hard.

Our Editorial Team

Our guides are written and reviewed by practitioners with direct experience in the topics they cover. We do not publish content on a subject without someone on the team having worked with it professionally.

James Whitfield — Founder & Lead Editor

James spent a decade in software engineering and technical project management before founding All Time Calculator. He has built scheduling systems, payroll integrations, and time-tracking tools professionally — which is why he knows exactly which date calculations trip people up. He writes and edits the guides on overtime law, deadline planning, Unix timestamps, and developer time utilities.

Dr. Priya Anand — Health & Science Contributor

Priya holds a doctorate in public health and has published research on circadian health and shift-work outcomes. She reviews and contributes to guides on jet lag recovery, sleep science, medication scheduling, and pregnancy dating. Her role is to ensure our health-adjacent content is grounded in current research and appropriately qualified.

Marcus O'Brien — Operations & Business Writer

Marcus has twelve years of experience in operations management and freelance consulting across logistics, finance, and distributed team coordination. He covers time tracking for independent contractors, ISO standards in business reporting, global scheduling for remote teams, and payroll compliance topics.

Editorial Standards

We hold our content to the following standards before publishing:

Every factual claim is traceable to a primary source, official standard, or jurisdiction-specific statute
Calculations are verified against independent sources before being used in guides
Health-related content is reviewed by a qualified professional and includes appropriate qualifications
Legal and payroll content notes the jurisdiction it applies to and does not substitute for professional advice
Articles are updated when underlying rules (tax thresholds, overtime rates, DST policy, ISO standards) change

Why It's Free

All Time Calculator is supported by display advertising. The calculators and guides are free to use without registration, and we do not sell user data. Advertising allows us to keep the tools free and to invest in maintaining accurate, up-to-date content. If you find the site useful, the most helpful thing you can do is share it with someone who needs it.

Get in Touch

Found an error in a calculation or guide? Have a suggestion for a calculator we should build? We read every message sent through our contact page and respond to substantive feedback. Errors in calculation logic or factual content are treated as high-priority fixes.