Years (365 days) to Days (yr to d)

Formula

1 yr = 365 d

days = years (365 days) × 365 — reverse: years (365 days) = days × 0.002739726027

The factor is derived from the SI definitions of both units (base unit: s) as listed in NIST SP 811; results on this page are shown to 6 significant figures, the API returns up to 12.

Worked examples

• 5 yr = 1825 d
• 12.5 yr = 4562.5 d
• 100 yr = 36500 d

Years (365 days) to days conversion table

FAQ

How many days are in one year?

1 yr = 365 d. The factor comes from the SI definitions of both units (NIST SP 811 / BIPM), so it is exact or correct to at least 10 significant figures.

What is the formula to convert years (365 days) to days?

Multiply the value in years (365 days) by 365: days = years (365 days) × 365. For example, 5 yr = 1825 d.

How do I convert days back to years (365 days)?

Multiply by the inverse factor 0.002739726027 (years (365 days) = days × 0.002739726027), or use the days-to-years (365 days) page.

Related conversions

• Days to years (365 days) (reverse)
• Time Converter — all time units in one tool
• Hours to Minutes
• Minutes to Hours
• Minutes to Seconds
• Seconds to Minutes
• Days to Hours
• Hours to Days
• Weeks to Days
• Days to Weeks

Machine access

• API: GET https://tttkmbb.com/api/v1/convert?value=5&from_unit=year_365&to_unit=day
• MCP: server https://tttkmbb.com/mcp, tool convert_units with {"value":5,"from_unit":"year_365","to_unit":"day"}
• Markdown: https://tttkmbb.com/conversion/years-to-days.md · JSON: https://tttkmbb.com/conversion/years-to-days.json (add ?value= for a result) · Units: /api/v1/units?quantity=time
• OpenAPI operationId: convert_units. Freshness: static. Authentication: none.

Sources

• NIST Special Publication 811 – Guide for the Use of the International System of Units (SI), Appendix B conversion factors (standard)
• BIPM – The International System of Units (SI Brochure, 9th edition) (standard)
• Wikipedia – Conversion of units (reference)