Days Between Dates Calculator - Calculate Duration

Calculate the exact number of days, weeks, months, and years between two dates. Find the duration instantly with our accessible, mobile-first date calculator.

Full original guide (expanded)

Audit: Complete

Formula (LaTeX) + variables + units

This section shows the formulas used by the calculator engine, plus variable definitions and units.

Formula (extracted text)

$ \text{ms}_{\text{perDay}} = 1000 \times 60 \times 60 \times 24 $ $ \text{Time}_{\text{diff}} = \text{EndDate}_{\text{ms}} - \text{StartDate}_{\text{ms}} $ $ \text{TotalDays} = \text{round}( \frac{\text{Time}_{\text{diff}}}{\text{ms}_{\text{perDay}}} ) $

Formula (extracted text)

$ \text{TotalDays}_{\text{inclusive}} = \text{TotalDays} + 1 $

Variables and units

No variables provided in audit spec.

Sources (authoritative):

Home — calcdomain.com · Accessed 2026-01-19
https://calcdomain.com/
Everyday Life — calcdomain.com · Accessed 2026-01-19
https://calcdomain.com/lifestyle-everyday
Time and Date — calcdomain.com · Accessed 2026-01-19
https://calcdomain.com/subcategories/time-date
Date Calculator (Add/Subtract Days) — calcdomain.com · Accessed 2026-01-19
https://calcdomain.com/date-calculator
Age Calculator — calcdomain.com · Accessed 2026-01-19
https://calcdomain.com/age-calculator
Time Duration Calculator — calcdomain.com · Accessed 2026-01-19
https://calcdomain.com/time-duration-calculator
Birthday Calculator — calcdomain.com · Accessed 2026-01-19
https://calcdomain.com/birthday

Changelog

Version: 0.1.0-draft
Last code update: 2026-01-19

0.1.0-draft · 2026-01-19

Initial audit spec draft generated from HTML extraction (review required).
Verify formulas match the calculator engine and convert any text-only formulas to LaTeX.
Confirm sources are authoritative and relevant to the calculator methodology.

Verified by Ugo Candido on 2026-01-19
Profile · LinkedIn

Formulas

(Formulas preserved from original page content, if present.)

Version 0.1.0-draft

Citations

Add authoritative sources relevant to this calculator (standards bodies, manuals, official docs).

Changelog

0.1.0-draft — 2026-01-19: Initial draft (review required).