Under international NIST and ISO standards, 1 kilometer equals exactly 1,000 meters or approximately 0.621371 miles (specifically 0.621371192 miles). Furthermore, 1 international inch is defined as exactly 25.4 millimeters (0.0254 meters), 1 foot equals 0.3048 meters (12 inches), and 1 statute mile equals exactly 1,609.344 meters or 5,280 feet.

A statute land mile (mi) equals exactly 5,280 feet, 1,760 yards, or 1,609.344 meters. In contrast, an international nautical mile (NM / nmi) equals exactly 1,852 meters (approximately 6,076.12 feet or 1.15078 statute miles). The nautical mile is based on one minute (1/60th of a degree) of arc of latitude along Earth's meridians and is the global standard for maritime and aviation navigation.

To convert decimal inches to a fraction, multiply the decimal fraction by your desired denominator (such as 16, 32, or 64), round to the nearest whole integer, and reduce the fraction by dividing the numerator and denominator by their greatest common divisor (GCD). For example, 0.4375 × 16 = 7, so 3.4375 inches converts exactly to 3 7/16 inches. Our Fractional Ruler tab provides interactive visual tape measurements and error delta calculations.

To convert human stature from feet and inches to centimeters, multiply total inches by 2.54. For instance, a height of 5 feet 10 inches equals (5 × 12) + 10 = 70 inches. Multiplying 70 × 2.54 yields 177.8 cm (or 1.78 meters). Conversely, divide centimeters by 2.54 to obtain total inches, then divide by 12 to extract whole feet and remaining inches. Our Height tab also correlates heights with demographic adult averages.

An Astronomical Unit (AU) is defined by the International Astronomical Union (IAU) as exactly 149,597,870,700 meters (approx. 92.96 million miles), representing the mean distance from Earth to the Sun. A Light Year (ly) is the total distance light travels through vacuum in one Julian year (365.25 days), equaling approximately 9.46073 × 10¹⁵ meters (about 63,241.07 AU or 5.88 trillion miles).

The US Survey Foot (defined as 1200/3937 meters, or approx. 0.3048006096 m) differs from the international foot (0.3048 m) by approximately 2 parts per million (0.01 foot per mile). Retained historically for US State Plane Coordinate Systems, the National Geodetic Survey (NGS) and NIST officially phased out the survey foot on December 31, 2022, in favor of the international standard foot.

The Travel & Pace tab takes any distance value in kilometers, miles, meters, or yards and calculates estimated walking time (at 5 km/h), running time (at 10 km/h), cycling time (at 20 km/h), and highway driving duration (at 80 km/h). It also computes step counts based on customizable stride lengths (default: 30 inches / 0.762 m) and estimated active metabolic calorie expenditures.

In the Batch Convert tab, you can paste lists of numbers (one per line) or drag-and-drop .txt and .csv files. The tool immediately transforms all dimensions into your target unit and generates a statistical summary card with count, total sum, arithmetic mean, and min/max range, with 1-click CSV spreadsheet download.

Click the '💻 API Code' button (or press Alt+S) to open the Developer API Code Snippets Studio. We provide verified, production-ready code implementations in TypeScript/JavaScript, Python 3, Go, Rust, Java, and Bash that utilize base SI meter conversion factors for high-precision math.

Yes, 100%. All arithmetic transformations, unit matrices, fractional rulers, and pacing algorithms run entirely client-side in your web browser via JavaScript. No numbers, files, or measurements are ever transmitted to or stored on external servers.