// conversions › 1 · Basic Converters
Convert time between nanoseconds and millennia via the second. Month = 30 days, year = 365.25 days (Julian).
result = value × (from→s) ÷ (to→s)
It converts convert time between nanoseconds and millennia via the second. month = 30 days, year = 365.25 days (julian) by first normalising your value to the SI base unit (second) and then scaling to your chosen target unit. This hub-and-spoke approach guarantees every unit pair is internally consistent.
90 minutes to hours: 90 × 60 = 5400 s (base), then ÷ 3600 = 1.5 hr.
Calendar months vary from 28 to 31 days, so this tool fixes a month at 30 days and uses the astronomical Julian year of 365.25 days (31,557,600 s). Smaller units are exact multiples of the SI second.
Project scheduling, physics, astronomy and historical timelines.
Conversions are exact ratios where the units are defined exactly (most SI and imperial units) and best-available constants otherwise. Extremely large or small magnitudes are shown in general (g) format; round-tripping through the base unit may introduce tiny floating-point differences in the final decimal places.