About Speedometer.tools
Speedometer.tools is a collection of free speed tools that work in your browser: a live GPS speedometer, speed tests for the car, train and walking, and converters between mph, km/h, knots and other units.
What we’re building
We want answering “how fast am I going?” to be as simple as opening a web page. Every tool on this site follows three rules:
- Free. No sign-up, no paywall and nothing to install.
- Private. Your location is processed on your own device and never sent to us.
- Accurate. Exact unit definitions, honest explanations of GPS limits and conservative real-world facts.
How the speedometer works
The online speedometer uses your browser’s standard Geolocation API. When you allow location access, your phone’s GPS reports your position and, on most phones, a speed value calculated from the Doppler shift of satellite signals. That speed is usually more precise than one derived from position changes alone.
All calculations — current, maximum and average speed, distance and trip time — run in JavaScript inside your browser. Readings with poor accuracy are filtered out so a GPS glitch doesn’t create a fake top speed. Nothing is uploaded; when you close the page, the trip data is gone.
How we keep the numbers right
- Exact unit definitions. Conversions use the international definitions: 1 mile = 1,609.344 m, 1 nautical mile = 1,852 m and 1 foot = 0.3048 m. Results are rounded only for display.
- Conservative facts. Speed limits, train speeds and records mentioned on our pages come from official or widely documented sources. Where values vary, we say “about” or “up to” instead of giving false precision.
- Reviewed dates. Pages show when they were last updated, and we revisit facts such as speed limits and app settings when they change.
- Clear limits. GPS speed is an estimate. We explain when it can be wrong and never present it as legal evidence.
Found a mistake?
If a conversion looks wrong, a fact is outdated or a tool doesn’t work on your device, please tell us via the contact page or email [email protected]. Corrections are our top priority.