How to Convert Hours to Minutes (and Seconds)
Hours and minutes are the units we use every day to schedule, plan, and measure time — but converting between them requires careful arithmetic, especially with mixed values like 2.5 hours or 1 hour 45 minutes. This guide explains the exact relationships, covers decimal hours (used in time tracking and spreadsheets), and gives you a quick reference table for the most common values.
The Basic Relationships
1 hour = 60 minutes (exact).
1 minute = 60 seconds.
1 hour = 3,600 seconds (60 × 60).
To convert hours to minutes: multiply by 60. For example, 3 hours × 60 = 180 minutes.
To convert minutes to hours: divide by 60. For example, 150 minutes ÷ 60 = 2.5 hours = 2 hours 30 minutes.
Why 60 Minutes in an Hour?
The division of hours into 60 minutes (and minutes into 60 seconds) comes from the ancient Babylonian sexagesimal (base-60) number system. The Babylonians used base-60 because it divides evenly by 2, 3, 4, 5, 6, 10, 12, 15, 20, and 30 — far more divisors than base-10.
This system was transmitted to ancient Greece and then to medieval Europe through Arabic astronomy, and it has remained the standard for time measurement ever since. Despite metric efforts (the French Revolutionary calendar tried a 10-hour day with 100-minute hours in the 1790s), 60-based time proved too entrenched to replace.
Decimal Hours
Spreadsheets, time-tracking software, and billing systems often use decimal hours rather than hours and minutes. 1.5 hours means 1 hour and 30 minutes; 0.25 hours means 15 minutes.
To convert decimal hours to hours and minutes: take the decimal part and multiply by 60. For example, 2.75 hours → 0.75 × 60 = 45 minutes → 2 hours 45 minutes.
To convert hours and minutes to decimal hours: divide the minutes by 60 and add to the hours. For example, 1 hour 20 minutes → 20 ÷ 60 = 0.333 → 1.333 hours.
Quick Reference Table
Common time conversions:
- 15 min = 0.25 hours
- 30 min = 0.5 hours
- 45 min = 0.75 hours
- 90 min = 1.5 hours
- 120 min = 2 hours
- 150 min = 2.5 hours
- 180 min = 3 hours
- 240 min = 4 hours
Time in Everyday Contexts
Flight times: A 2-hour 45-minute flight is 165 minutes. Connecting flight calculations add minutes directly: a 45-minute layover after a 1h 55m flight followed by a 3h 10m leg totals 355 minutes = 5 hours 55 minutes.
Cooking and baking: A recipe that cooks for 1 hour 15 minutes at 180°C requires 75 minutes of oven time.
Exercise: A 90-minute training session is 1.5 hours. At an average pace of 10 km/h, that covers 15 km.
Time billing: 2 hours 20 minutes billed at $150/hour = 2.333 hours × $150 = $350.
Conclusion
1 hour = 60 minutes = 3,600 seconds. To convert hours to minutes, multiply by 60. For decimal hours, multiply the decimal part by 60 to get minutes. For time billing and spreadsheets, use decimal hours: 1 hour 45 minutes = 1.75 hours. Use our free time converter for any combination instantly.