Days to Hours Converter
Enter the time in days below to convert it to hours.
Convert Days to Hours
Enter a value in days (d) to convert to hours (hr).
Day to Hour Conversion Table
Table showing various day measurements converted to hours. Click any preset value or arrow to load it into the converter.
How to Convert Days to Hours
To convert days to hours, multiply the time by the following conversion ratio: 24 hours/day.
Since one day is equal to 24 hours, you can use this simple formula to convert:
The time in hours is equal to the time in days multiplied by 24.
For example, here's how to convert 5 days to hours using the formula above.
How Many Hours Are in a Day?
There are 24 hours in a day, which is why we use this value in the formula above.
Our day to hour calculator automatically converts your time measurements with full decimal and scientific precision across US customary, imperial, and SI metric standards.
Days and hours are both units used to measure time. Keep reading to learn more about each unit.
What Is a Day?
A day is a unit of time equal to 86,400 seconds (s), the base unit for time. Civil day equal to 24 hours or 86,400 seconds. [1]
The day is classified as a standard unit of time. Days can be abbreviated as d; for example, 1 day can be written as 1 d.
When working with days (d) in formulas or technical specifications, always verify whether your target system uses SI metric, US customary, or British imperial standards.
In practice, days (d) are widely used across large-scale industrial, bulk, and macro-level time specifications within international standard workflows, engineering documentation, and technical data sheets.
What Is an Hour?
An hour is a unit of time equal to 3,600 seconds (s), the base unit for time. Equal to 60 minutes or 3,600 seconds. [2]
The hour is classified as a standard unit of time. Hours can be abbreviated as hr; for example, 1 hour can be written as 1 hr.
When working with hours (hr) in formulas or technical specifications, always verify whether your target system uses SI metric, US customary, or British imperial standards.
In practice, hours (hr) are widely used across large-scale industrial, bulk, and macro-level time specifications within international standard workflows, engineering documentation, and technical data sheets.
When converting time between days (d) and hours (hr), keep full floating-point precision (1 d = 24 hr; 1 hr = 0.0416667 d) during intermediate calculations and round only the final hour figure to match your instrument tolerance.
More Day & Hour Conversions
Need to calculate in the opposite direction? Use our hours to days converter (hr to d) to switch your starting unit immediately. You can also explore related tools such as converting minutes to hours, converting seconds to hours, or converting days to weeks.
Frequently Asked Questions
References
- [1]NIST OWM StandardNIST OWM (SI Units — Time)·Time Metrology Standard — Days (d) to Hours (hr)
- [2]BIPM SpecificationBIPM (SI Base Unit: Second (s))·Unit Specifications: Day (d) & Hour (hr)
- [3]NIST CUU ReferenceNIST CUU (Non-SI Units Accepted for Use (min, h, d))·Conversion Factors & Mathematical Basis (d to hr)