Editorial Policy
How we research, verify, review, and correct everything on this site.
How we verify
Every number on this site traces back to a primary, authoritative source rather than to another website. The definition of the second comes from the BIPM (SI), the standard work year and 40-hour week from the U.S. Fair Labor Standards Act, calendar rules from the Gregorian calendar definition, and time-zone behavior from the IANA time zone database.
The full source list, with links, is on our methodology page. Calculator results are computed from these formulas in your browser — there is no hidden rounding or estimation beyond what each tool states.
Who writes and reviews
Content is written and maintained by Darrell Donaghy, Founder. Darrell Donaghy is an indie developer based in Minnesota who has been building web tools for 25 years. By day he's a Marketing Director with 15 years of experience. HowManyHoursIn.com is one of several side projects where he builds small, focused utilities he uses himself. Each explainer page shows a "last reviewed" date, and pages are re-checked when the underlying standards change (for example, a leap-second announcement) or when a reader reports an issue.
Corrections policy
We aim for the numbers to be exactly right. If you find an error — a wrong figure, a broken calculation, an out-of-date standard, or an unclear explanation — please tell us and we will fix it.
- Email hello@mlighthouse.com with the page URL and what looks wrong.
- We review correction reports within a few business days.
- Substantive factual fixes update the page's "last reviewed" date so the change is visible.
Advertising & independence
This site is supported by advertising (Google AdSense). Advertisers do not influence the calculations, explanations, or recommendations on any page. Ad content is served by Google and is clearly distinguishable from our editorial content. See our privacy policy for how advertising cookies are handled.