Convert Gregorian Years to Megayears
Convert Gregorian Years (yr) to Megayears (Ma) instantly and accurately.
Conversion Formula
Ma = yr × 1.000000000e-6
About Gregorian Years
The Gregorian year = exactly 365.2425 days = 31,556,952 s (mean over the 400-year cycle with 97 leap years). The Julian calendar (45 BCE) used 365.25 days; Gregorian reform (1582) dropped 10 days and amended the centennial rule. Britain adopted it in 1752; Greece in 1923. Carbon-14 dates are reported in 'years BP' (before 1950 CE). 1 yr = 365.2425 d = 8,765.82 h = 31,556,952 s.
About Megayears
A megayear (1 Ma) = 10⁶ yr ≈ 3.156 × 10¹³ s - the timescale of geology and tectonic evolution. The K-Pg mass extinction at 66.0 Ma; Cambrian explosion ~538.8 Ma; Great Oxygenation Event ~2,400 Ma. Plate motion at 2-10 cm/yr = 200-1,000 km per Ma (Atlantic ~3,000 km wider since Pangaea rifting ~200 Ma ago). Background extinction rate measured in extinctions per million species-years. 1 Ma = 10⁶ yr.
Quick Reference Table
| Gregorian Years (yr) | Megayears (Ma) |
|---|---|
| 1 yr | 1 × 10-6 Ma |
| 2 yr | 2 × 10-6 Ma |
| 5 yr | 5 × 10-6 Ma |
| 10 yr | 1 × 10-5 Ma |
| 25 yr | 2.5 × 10-5 Ma |
| 50 yr | 5 × 10-5 Ma |
| 100 yr | 1 × 10-4 Ma |