---
title: "Deep Time Calendar: Earth's History in a Year | Fossil Wharf"
description: "Squeeze Earth's 4.54 billion years into one calendar year, or along a walk, a pitch or a toilet roll, and see where life, dinosaurs and humans land."
url: https://fossilwharf.me/deep-time-calendar/
---

4.54 billion years in one year

# Deep time calendar

If Earth formed at midnight on 1 January, the dinosaurs died out on 26 December and our own species turned up at 23:25 on New Year's Eve. This calendar squeezes Earth's 4.54 billion years into one year, and lays the same history along a walk, a football pitch or a toilet roll of any length.

## How the deep time calendar works

The year starts with Earth's formation, 4.54 billion years ago, and ends at midnight on 31 December, today. Each event's date is simply how far through Earth's history it happened: 66 million years ago is 98.5 percent of the way through, which is 26 December. Every day of the calendar stands for about 12.4 million years and every second for about 144 years, so the 300,000 years of our own species fit into the last 35 minutes.

The line works the same way. On the 4.54 km walk each metre is one million years: the Cambrian Explosion begins only 539 m from the end, and the peak of the last ice age is the final 2.7 cm. On a 100 m pitch, megalodon disappears 8 cm before the goal line. For a toilet roll, count the sheets and measure one, and every sheet becomes millions of years.

Print the page for a classroom or a beach walk: the buttons and menus are left off the printout.

## Sources

Earth's age, 4.54 billion years with an uncertainty of less than 1 percent: [USGS, Age of the Earth](https://pubs.usgs.gov/gip/geotime/age.html). Each event in the table links to its own source: peer-reviewed papers (Wilde et al. 2001; Djokic et al. 2017; Poulton et al. 2021; Matthews et al. 2021; Wellman et al. 2003; Burgess et al. 2014; Martínez et al. 2011; Boessenecker et al. 2019; Villmoare et al. 2015; Hublin et al. 2017; Clark et al. 2009), the [ICS chart v2026/06](https://stratigraphy.org/chart), the Smithsonian, the Natural History Museum and the Charmouth Heritage Coast Centre.

## Questions

**If Earth's history were a year, when would humans appear?**

Homo sapiens, about 300,000 years ago, arrives at 23:25 on 31 December, about 35 minutes before midnight. The first members of our genus, 2.8 million years ago, arrive at 18:35 the same day.

**When would the dinosaurs live on the calendar?**

The first dinosaurs, some 230 million years ago, appear on 13 December; they die out with the ammonites on 26 December, 66 million years ago.

**Why does the year start with 4.54 billion years?**

That is the age of the Earth from meteorites and lead isotopes, given by the USGS with an uncertainty of less than 1 percent.