Deep Time Duration Calculator
Compare two dates as elapsed days, weeks, years, decades, centuries and millennia so long spans feel readable without hiding the arithmetic.
Date span and deep-time scale calculator
Deep Time Duration Calculator
Compare two dates as elapsed days, weeks, years, decades, centuries and millennia so long spans feel readable without hiding the arithmetic.
Deep Time Duration Calculator turns a date span into human, historical and epoch-scale units.
This staged candidate reframes the Spatial Chronograph workshop build as a clearer duration calculator. The 3 Aug 2026 version adds the newer Deep Time Calculator source with embed and citation panels while preserving the earlier repaired route for comparison.
Method and approval route
This staged build is being prepared for calculator approval.
Intended permanent route after approval: /calculators/deep-time-duration-calculator/. This staged page stays noindex until the name, source notes, mobile layout and calculator behavior pass review.
Date-span basis
The calculator should treat each input as a date-only value, compare the two selected dates, and report the elapsed span separately from inclusive endpoint counting.
Scale conversion
Days, weeks and larger units should be shown as readable approximations where calendar-month and leap-year detail would otherwise imply false precision.
User boundary
This is a general duration and timeline tool, not a legal-deadline, rental, payroll, subscription, business-day or astronomical ephemeris ruling.
NIST - Time and frequency from A to Z
ISO - ISO 8601 date and time format overview
Britannica - Gregorian calendar
Interactive workshop instrument