Free Online Speed Converter — Convert Any Speed Unit Instantly
Speed converter supporting 12 units including km/h, mph, m/s, knots, and Mach. Get precise conversions for driving, aviation, physics, and everyday use — entirely in your browser.
Convert Your Speed Value
How to Use This Speed Converter
Enter Your Speed Value
Type the numeric speed value you want to convert into the input field. For example, enter 100 for 100 km/h.
Select the Source Unit
Choose the unit you are converting from using the "From Unit" dropdown. Options include km/h, mph, m/s, knots, and more.
Select the Target Unit
Choose the unit you want to convert to using the "To Unit" dropdown. Pick any of the 12 available speed units.
Click Convert Speed
Press the Convert Speed button or hit Enter to instantly see your converted result with full precision.
Copy or Reset Your Result
Use the Copy Result button to copy the converted value to your clipboard, or click Clear to start a new conversion.
Key Features of Speed Converter
100% Free Speed Conversion
Convert between any speed units unlimited times without any charges, subscriptions, or hidden fees.
12 Speed Units Supported
Covers km/h, mph, m/s, ft/s, knots, Mach, cm/s, mm/s, speed of light, yd/s, km/s, and mi/s.
Instant Real-Time Results
Get precise conversions immediately with a complete conversion table showing all 12 units at once.
Privacy-Safe Browser Processing
Every calculation runs locally in your browser. Zero data transmission, zero tracking, zero server dependency.
No Signup or Login Required
Start converting instantly — no account creation, no email verification, no personal information needed.
Mobile-Friendly Responsive Design
Optimised for phones, tablets, and desktops with touch-friendly controls and adaptive layout.
How Speed Conversion Works
Result = Input Value × (Source Unit Factor ÷ Target Unit Factor)Each speed unit has a fixed conversion factor relative to metres per second (m/s), the SI base unit for speed. The converter first translates your input to m/s, then converts from m/s to the target unit.
Conversion Reference Factors (to m/s)
For example, converting 100 km/h to mph: first convert to m/s (100 ÷ 3.6 = 27.7778 m/s), then convert to mph (27.7778 ÷ 0.44704 = 62.1371 mph). Indian highway speed limits of 100–120 km/h correspond to roughly 62–75 mph.
Assumptions: Mach number assumes standard sea-level atmospheric conditions (15°C, 101,325 Pa). At higher altitudes or different temperatures, the speed of sound changes. The speed of light is the exact value defined by the SI system since 2019.
Practical Examples
Indian Expressway Speed Limit
Input: 120 km/h
Result: 74.5645 mph | 33.3333 m/s | 64.7948 knots
Use Case: Understanding the speed limit on the Mumbai-Pune Expressway when comparing with international road standards.
Wind Speed for Cyclone Warning
Input: 90 knots
Result: 166.68 km/h | 103.5619 mph | 46.3 m/s
Use Case: IMD cyclone bulletins often report wind speeds in knots. Converting to km/h helps the public understand the severity.
US Highway Speed to Metric
Input: 65 mph
Result: 104.6073 km/h | 29.0576 m/s | 56.4791 knots
Use Case: An Indian traveller driving in the United States needs to understand the 65 mph speed limit in familiar km/h terms.
Physics Problem: m/s to km/h
Input: 343 m/s (approximate speed of sound)
Result: 1,234.8 km/h | 767.269 mph | Mach 1.008
Use Case: A student solving a physics problem can quickly verify the speed of sound in multiple units for cross-referencing.
What Is a Speed Converter?
A speed converter is a tool that translates a velocity measurement from one unit to another. Speed — the rate at which an object covers distance — is expressed in dozens of units worldwide, from the everyday km/h used on Indian roads to the nautical knots used in maritime navigation and the Mach numbers quoted in aerospace engineering.
This converter is designed for students solving physics problems in m/s, drivers comparing Indian km/h limits with American mph signs, aviation enthusiasts interpreting knot-based weather reports, and anyone who needs fast and reliable unit translation. It handles 12 of the most commonly used speed units, covering metric, imperial, nautical, and scientific scales.
Unlike many online converters that only show a single result, this tool displays a complete conversion table across all 12 units simultaneously. This is particularly useful when you need to communicate a speed value across different professional contexts — for instance, explaining a spacecraft's velocity in both km/s and as a fraction of the speed of light.
Sources and Methodology
All conversion factors used in this tool are based on internationally standardised definitions. The metre-per-second (m/s) serves as the base unit, consistent with the International System of Units (SI). The mile-to-kilometre relationship (1 mile = 1.609344 km exactly) follows the 1959 International Yard and Pound Agreement. The Mach conversion uses the standard atmosphere speed of sound at sea level (340.29 m/s at 15°C). The speed of light uses the exact SI-defined value of 299,792,458 m/s.
Important Considerations
Mach number conversions assume standard sea-level conditions. In reality, the speed of sound varies with temperature and altitude — at 11,000 metres altitude, Mach 1 is approximately 295 m/s rather than 340 m/s. For precise aerospace calculations, use tools that account for atmospheric conditions. All other conversion factors are exact or precise to at least 6 significant figures.
Frequently Asked Questions
Yes, this speed converter is 100% free to use with no hidden charges, no signup required, and no premium tier. You can perform unlimited conversions at any time.
Absolutely. All conversions happen directly in your browser using JavaScript. No data is sent to any server, no cookies are stored, and no personal information is collected.
This converter uses internationally standardised conversion factors defined by SI units and BIPM standards. Results are accurate to 6 decimal places, suitable for engineering, academic, and everyday use.
You can convert between 12 speed units: kilometres per hour (km/h), miles per hour (mph), metres per second (m/s), feet per second (ft/s), knots, Mach number, centimetres per second (cm/s), millimetres per second (mm/s), speed of light (c), yards per second (yd/s), kilometres per second (km/s), and miles per second (mi/s).
Kilometres per hour (km/h) is the metric speed unit used in India and most countries worldwide. Miles per hour (mph) is primarily used in the United States and United Kingdom. 1 mph equals approximately 1.60934 km/h.
Mach 1 represents the speed of sound, which is approximately 1,225.044 km/h or 761.207 mph at sea level and standard atmospheric conditions (15°C). The actual value varies with temperature and altitude.
Yes. Wind speed is commonly measured in knots (nautical), km/h, or mph depending on the country. This converter handles all three units, making it useful for weather reports, sailing, and aviation contexts.
The speed of light in a vacuum is exactly 299,792.458 km/s, which equals approximately 1,079,252,848.8 km/h. This is the universal speed limit in physics.
To convert km/h to m/s, divide the value by 3.6. For example, 90 km/h equals 25 m/s. This converter does this calculation instantly for you with full precision.
Yes. The speed converter is fully responsive and works on all devices including Android and iOS phones, tablets, laptops, and desktops. The interface adapts to your screen size automatically.