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You are filling in a timesheet, and the system asks for hours in decimals. Your shift lasted 1 hour and 20 minutes. Do you type 1.20? Stop right there, because that is one of the most common time conversion mistakes.
So, what is 1 hour 20 minutes in decimal? The answer is 1.33 hours (rounded to two decimal places).
Let's look at why, and how you can work this out for any time value without a calculator headache.
The Quick Answer: 1 Hour 20 Minutes in Decimal
1 HOUR + 20 MINUTES IN DECIMAL FORM
80 minutes ÷ 60 = 1.3333...
Rounded to 2 decimal places
The exact value is 1.3333... with the 3 repeating forever, but most payroll, billing, and invoicing systems round it to 1.33.
Why Is 1 Hour 20 Minutes Not 1.20 in Decimal?
This is where most people slip up. Our everyday clock runs on a base-60 system: one hour has 60 minutes. Decimals, however, run on a base-10 system, where each unit is split into tenths and hundredths.
The Common Conversion Mistake
When you write 1.20, a decimal system reads it as 1 hour and 20 hundredths of an hour.
So, 1.20 hours actually means 1 hour and 12 minutes.
That is 8 minutes short of what you actually worked. Over a week of shifts, those missing minutes add up to real money.
The number after the decimal point is a fraction of an hour, not a count of minutes.
How to Write 1 Hour and 20 Minutes in Decimal (Step by Step)
Wondering how to write 1 hour and 20 minutes in decimal yourself? Follow these three easy steps.
You have 1 full hour, so your whole number is 1.
Take the leftover minutes and divide them by 60:
Combine the whole hours and the decimal minutes:
This rounds to 1.33 hours.
The Formula
Plug in your own numbers, and you can convert any duration into decimal hours.
A Shortcut
Since 20 minutes is exactly one-third of an hour (20 ÷ 60 = 1/3), you can remember that 20 minutes is always 0.33 hours as a rounded value. Add the whole hours, and you are done.
1 Hour 20 Minutes in Decimal: Real-Life Examples
Numbers feel more meaningful when you see them in action. Here is how 1.33 hours plays out in common situations.
Minutes to Decimal Hours Conversion Chart
Bookmark this quick reference table for everyday conversions.
| Time | Decimal Hours |
|---|---|
| 1 hour 5 minutes | 1.08 |
| 1 hour 10 minutes | 1.17 |
| 1 hour 15 minutes | 1.25 |
| 1 hour 20 minutes | 1.33 |
| 1 hour 30 minutes | 1.50 |
| 1 hour 40 minutes | 1.67 |
| 1 hour 45 minutes | 1.75 |
| 1 hour 50 minutes | 1.83 |
| 2 hours | 2.00 |
Quick Reminder
Always divide minutes by 60 before adding them to whole hours.
How to Convert Decimal Hours Back to Hours and Minutes
What if you want to go the other way? Easy.
- Take the decimal part: 0.33
- Multiply by 60: 0.33 × 60 = 19.8, which is about 20 minutes
- Combine with the whole number: 1 hour 20 minutes
If you use the exact 0.3333, you get precisely 20 minutes.
Conclusion
Converting time to decimals does not have to be confusing. Just remember the golden formula: hours + (minutes ÷ 60). Using it, 1 hour 20 minutes in decimal is 1.33 hours, a small number that can make a big difference to your paycheck, invoice, or project report.
The next time someone asks you how to write 1 hour and 20 minutes in decimal, you will have the answer ready, along with the reasoning behind it.
You can opt for our Advanced Math or Vedic Math+Mental Math courses. Our Math Quiz for grades 3rd, 4th, 5th, and 6th helps in further exciting and engaging in mathematics with hands-on lessons.
