Geologic Time Converter
Convert Ga, Ma, ka, and years, then identify the matching major Earth-history interval using the ICS 2026/06 chart.
Use the Geologic Time Converter
Unit Converter
Elapsed-duration conversion. A non-negative value can also be interpreted as an age before present.
Earth age interpretation
66 Ma- Eon
- Phanerozoic
- Era
- Cenozoic
- Period / epoch
- Paleogene – Paleocene
- Context
- Mammals diversify after the K–Pg boundary
Select a row to load its older boundary. This is a concise major-interval reference based on the ICS chart 2026/06, not the full chart.
| Eon | Era | Period / Epoch | Start (Ma) | Duration (Ma) |
|---|
| Symbol | Full Name | Equals (years) |
|---|---|---|
| Ga | Gigaannum | 1,000,000,000 |
| Ma | Megaannum | 1,000,000 |
| ka | Kiloannum | 1,000 |
| yr | Year | 1 |
| dec | Decade | 10 |
| cent | Century | 100 |
| mil | Millennium | 1,000 |
Notation note
Age and duration are different. This converter uses the same decimal factors for arithmetic, but only non-negative ages from 0 to 4,540 Ma are mapped to Earth-history intervals. The term “yr BP” is especially associated with radiocarbon reporting; do not assume every elapsed duration has a 1950 CE epoch.
Summary
Convert Ga, Ma, ka, and years, then identify the matching major Earth-history interval using the ICS 2026/06 chart.
How it works
- Select the input unit (Ma, Ga, ka, years, decades, centuries, or millennia).
- Type a finite numeric duration; all equivalent units update instantly.
- For values from 0 to 4,540 Ma, the age interpretation card identifies the matching major interval.
- Use the "Geologic Time Scale" tab to browse the concise reference.
- Click any row in the reference table to pre-fill the converter with that age.
- Copy any result with the copy icon next to each output field.
Use cases
- Translate Ma/Ga/ka values from scientific papers into intuitive time spans.
- Cross-check dates when reading about the dinosaur era, ice ages, or Earth formation.
- Educational aid for geology, paleontology, or Earth science students.
- Quick reference when comparing different geologic periods side by side.
- Convert radiometric dating results between common notation styles.
- Understand deep-time values cited in climate science and astronomy.
- Look up when a specific geologic period started and how long it lasted.
- Confirm unit conversions before including them in reports or articles.