How many hours are in 1 day?

1 d equals 24 h. This is an exact conversion factor defined by NIST.

How do I convert days to hours?

Multiply the value in d by the conversion factor. For example, 10 d = 240 h. Use our calculator above for instant results.

Is the days to hours conversion exact?

Yes, this conversion is mathematically exact based on the international definition of these units (NIST SP 811).

Days to Hours (d → h) — Free Online Converter

Why Convert Days to Hours?

Converting between days (d) and hours (h) is one of the most common time conversions. Whether for engineering, cooking, travel, or science, knowing how to quickly convert d to h saves time and prevents errors.

Time conversions between d and h are fundamental in project management, cooking, fitness, and daily scheduling. Project managers convert between hours, days, and weeks when planning sprints and estimating delivery timelines. Cooking recipes specify times in minutes or hours depending on the technique. In fitness, interval training requires precise conversions between minutes, seconds, and sometimes hours for endurance events like marathons.

How to Convert Days to Hours

To convert days to hours, use the following formula:

h = d × 24

Example: 1 d = 24 h

For example, 5 d = 120 h, 10 d = 240 h, and 100 d = 2400 h. Our calculator above performs this conversion instantly with full precision — no rounding errors.

Common Use Cases

One full day: 1 d = 24 h
One week: 7 d = 168 h
A typical weekend getaway: 3 d = 72 h
A standard two-week vacation: 14 d = 336 h
One year: 365 d = 8760 h

Common Mistakes to Avoid

Month/year ambiguity: "1 month" varies from 28 to 31 days. For precise calculations, always specify the exact number of days.
Leap year errors: Don't assume 1 year = 365 days. For multi-year calculations, account for leap years (avg = 365.2425 days).
Time zone confusion: When scheduling across time zones, always specify UTC offset. "3 PM" means different things in different countries.

Pro Tips

Memorize the factor: 1 d = 24 h. For quick mental math, remember this base conversion.
Quick reference: 5 d = 120 h · 10 d = 240 h · 25 d = 600 h · 50 d = 1200 h · 100 d = 2400 h
Bookmark this page: Save this converter for instant access. It works offline once loaded — no internet needed.

Days to Hours Conversion Table

d	h
0.01 d	0.24 h
0.1 d	2.4 h
0.5 d	12 h
1 d	24 h
2 d	48 h
5 d	120 h
10 d	240 h
20 d	480 h
50 d	1200 h
100 d	2400 h
500 d	12000 h
1000 d	24000 h

All values in this table are mathematically exact per NIST SP 811.

Days → Hours

d → h Reference Table

🌍 Real-World Examples