42 mph is approximately 67.5928 kmh.
To convert miles per hour (mph) to kilometers per hour (kmh), you multiply the speed by 1.60934 because 1 mile equals 1.60934 kilometers. So, 42 mph times 1.60934 gives the equivalent speed in kmh.
Conversion Tool
Result in kmh:
Conversion Formula
The formula to convert mph to kmh is:
kmh = mph × 1.60934
This works because one mile equals 1.60934 kilometers. When you have a speed in miles per hour, multiplying by this factor changes the unit from miles to kilometers while keeping the time unit hour the same.
Example:
- Speed = 42 mph
- Multiply by 1.60934: 42 × 1.60934 = 67.59228 kmh
- Result: 67.59228 kmh
Conversion Example
- Convert 30 mph to kmh:
- Multiply 30 × 1.60934 = 48.2802 kmh
- So, 30 mph equals approximately 48.2802 kmh
- Convert 55 mph to kmh:
- 55 × 1.60934 = 88.5137 kmh
- Therefore, 55 mph is about 88.5137 kmh
- Convert 10 mph to kmh:
- 10 × 1.60934 = 16.0934 kmh
- So, 10 mph equals 16.0934 kmh
- Convert 65 mph to kmh:
- 65 × 1.60934 = 104.6071 kmh
- Hence, 65 mph is 104.6071 kmh
Conversion Chart
The chart below shows mph values from 17.0 to 67.0 converted to kmh. You can use it quickly to find the equivalent speed without calculation. Just find the mph value, and see the corresponding kmh.
| mph | kmh | mph | kmh |
|---|---|---|---|
| 17.0 | 27.3588 | 42.0 | 67.5928 |
| 22.0 | 35.4055 | 47.0 | 75.6390 |
| 27.0 | 43.4522 | 52.0 | 83.6857 |
| 32.0 | 51.4989 | 57.0 | 91.7324 |
| 37.0 | 59.5456 | 62.0 | 99.7791 |
| 67.0 | 107.8278 |
Related Conversion Questions
- How fast is 42 mph in kmh exactly?
- What is the kmh equivalent if I drive at 42 miles per hour?
- How do I convert 42 mph to kmh manually?
- Is 42 mph faster or slower than 67 kmh?
- What does 42 mph equal in kilometers per hour on a speedometer?
- How many kmh are 42 mph when traveling by car?
- What number should I look for in kmh if I read 42 mph?
Conversion Definitions
mph: Miles per hour (mph) is a unit measuring speed or velocity, indicating how many miles are traveled in one hour. It is commonly used in the United States and the United Kingdom for road speeds. The unit combines distance (miles) with time (hours) to express speed.
kmh: Kilometers per hour (kmh) expresses speed by showing how many kilometers are covered in one hour. It is the standard unit of speed in most countries worldwide, particularly where the metric system is adopted. Kilometers measure distance, and hours represent time.
Conversion FAQs
Why does multiplying mph by 1.60934 give kmh?
Because 1 mile equals 1.60934 kilometers, multiplying a speed in miles per hour by 1.60934 converts the distance portion from miles to kilometers, keeping the time portion in hours, thus giving kilometers per hour.
Is the conversion factor always exactly 1.60934?
The factor 1.60934 is a rounded standard value. The exact factor is slightly more precise but for most uses, 1.60934 is accurate enough. Small deviations do not affect everyday speed conversions noticeably.
Can I convert kmh back to mph using the same factor?
No, converting kmh to mph requires dividing by 1.60934 because you are converting kilometers back to miles, the reverse of multiplying when converting mph to kmh.
Does wind or terrain affect mph to kmh conversion?
No, the conversion between mph and kmh is purely mathematical based on units, so external factors like wind or terrain do not influence the conversion result.
Are mph and kmh used in different countries?
Yes, mph is mostly used in the US, UK, and some other countries, while kmh is standard for most countries following the metric system. This difference can require conversions when traveling or comparing speeds internationally.
Last Updated : 21 June, 2025
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Sandeep Bhandari holds a Bachelor of Engineering in Computers from Thapar University (2006). He has 20 years of experience in the technology field. He has a keen interest in various technical fields, including database systems, computer networks, and programming. You can read more about him on his bio page.