Fuel Economy Converter

WHAT IT DOES

Fuel Economy Converter transforms fuel efficiency values between four common measurement systems: MPG (US), MPG (UK), km/L, and L/100km. Enter a fuel economy value in any unit and see the converted result instantly. The tool handles the reciprocal relationship between consumption units (L/100km) and distance-per-volume units (MPG, km/L). You can swap the input and output units with one click, adjust the decimal precision (0-10 places), and copy the result to your clipboard. A comparison display shows the unit names alongside the values for context.

WHERE IT RUNS

The extension runs entirely within your browser's local environment using the BotGentz framework. All fuel economy conversion, unit calculation, and formatting occur on your machine without any network requests. No fuel economy data, conversion results, or user activity is ever transmitted, uploaded, or stored externally. The tool works on any website and respects the browser's security boundaries, operating within the isolated extension sandbox. Fuel economy conversion uses standard conversion factors.

HOW TO USE

Click the extension toolbar icon to open the Fuel Economy Converter panel. Enter a fuel economy value in the input field. Select the "From" unit (MPG (US), MPG (UK), km/L, or L/100km) and the "To" unit. The conversion result appears instantly if auto-convert is enabled. Click "Convert" to manually trigger a conversion. Click "Swap Units" to exchange the from and to units. Click "Copy Result" to copy the conversion result to your clipboard. Toggle "Auto convert" to enable or disable real-time conversion. Toggle "Show comparison" to display the unit names alongside the values. Toggle "Swap default direction" to control whether the default from/to direction is swapped. Adjust the "Decimal places" (0-10) to control the precision of the result. The tool updates automatically when you change settings.

THE FUEL ECONOMY CONVERSION ENGINE — WHY IT WORKS

Fuel economy units are not all directly proportional—L/100km is a consumption unit (inverse of efficiency), while MPG and km/L are distance-per-volume units. This tool uses a two-step conversion engine that first converts any input to L/100km as the base unit, then converts from L/100km to the target unit. The conversion factors are: 1 MPG (US) = 235.214583 L/100km, 1 MPG (UK) = 282.480936 L/100km, 1 km/L = 100 L/100km, and L/100km is the base unit itself. For example, to convert 30 MPG (US) to L/100km: L/100km = 235.214583 / 30 = 7.84. To convert L/100km to MPG (US): MPG = 235.214583 / L/100km. This approach handles the inverse relationship correctly and ensures consistent results across all four unit types.

THE PANEL

The Fuel Economy Converter panel is fully draggable by its title bar and remembers its position on screen per website. It snaps to the edges of your browser window for clean alignment. Collapse the panel to a compact icon strip using the minimize button, restoring it with a single click. Resize the panel by dragging any edge or corner; the input area, unit selectors, and result display adjust proportionally. Press the Escape key to close the panel instantly. The panel maintains independent state for each browser tab, allowing you to convert fuel economy values in multiple tabs simultaneously.

PLEASE NOTE

This extension requires the free BotGentz extension framework to be installed and enabled. The tool supports four common fuel economy units; additional units are not supported. MPG (US) and MPG (UK) use different gallon sizes (US gallon = 3.785 liters, UK gallon = 4.546 liters). The auto-convert feature triggers on every input event; disabling it can improve performance on slower devices. All conversion data is processed locally and is never transmitted, logged, or shared. The extension requests no network permissions and functions entirely offline. The source code is fully auditable and available for review.