Need to measure time in millennia? This millennia calculator computes the exact number of millennia between any two dates.
Millennia calculator
How it works
Pick a start date and end date. The calculator shows the time span in millennia (to three decimal places), plus equivalent years, decades, and centuries. Works for historical dates too - the default shows time since 1 AD.
Measuring deep time
Millennia are the natural unit for:
- Human civilization: About 10-12 millennia old
- Recorded history: About 5 millennia
- Major religions: 1-4 millennia
- Long-term projections: Climate, geology, astronomy
