Distance Calculator

This calculator uses the Haversine formula to calculate the shortest distance between two points on the Earth's surface. The Haversine formula is based on spherical trigonometry and assumes the Earth is a perfect sphere to determine the great circle distance between two coordinates. This method is highly accurate for relatively short distances and is widely used in aviation and maritime navigation. While the Earth is actually more of an ellipsoid than a perfect sphere, the Haversine formula provides sufficiently accurate results for most practical purposes.

GPS location accuracy depends on several factors. Typically, smartphone GPS has an error margin of 5-10 meters in open outdoor spaces. However, accuracy can significantly decrease indoors, between tall buildings, or inside tunnels. The GPS chipset performance, satellite signal strength, and atmospheric conditions also affect accuracy. Modern smartphones use multiple satellite navigation systems (GPS, GLONASS, Galileo, Beidou) together to improve accuracy. For more precise positioning, A-GPS (Assisted GPS) features that utilize Wi-Fi and cellular tower information can help.

The distance provided by this calculator is the 'straight-line distance' or 'great circle distance', which is the shortest distance when connecting two points directly. However, when traveling by car or train, you must follow roads, making the journey longer. Due to road curves, detours, and geographical obstacles like mountains and rivers, actual travel distance can be 1.2-1.5 times the straight-line distance or more. For example, while the straight-line distance from Seoul to Busan is about 325km, the actual driving distance via the Gyeongbu Expressway exceeds 400km. Air travel is closer to straight-line distance but still doesn't match exactly due to air route characteristics.

Bearing refers to the compass direction from the starting point to the destination, measured in degrees (°). It starts at 0° for true north and is measured clockwise. For example, 90° means due east, 180° means due south, and 270° means due west. In navigation and aviation, this bearing is called 'azimuth' and indicates the initial direction to the destination. However, for long-distance travel, since the Earth is spherical, the initial bearing may differ from the final bearing. This is called 'great circle route', and long-distance flights consider this when setting their paths.

A nautical mile is a distance unit primarily used in maritime and aviation fields, where 1 nautical mile equals approximately 1.852km. It's defined as the distance corresponding to one minute of latitude (1/60 degree) on the Earth's surface. In contrast, a regular mile (statute mile or land mile) is mainly used on land, where 1 mile equals approximately 1.609km. Therefore, 1 nautical mile equals about 1.15 statute miles. Nautical miles are preferred in aviation and maritime navigation because they directly correlate with the latitude/longitude coordinate system, making calculations convenient. Aircraft and ship speeds are also expressed in 'knots' (nautical miles per hour), which is an internationally standardized unit.

Estimated driving time is calculated based on an average speed of 80 km/h, while estimated flight time uses an average speed of 900 km/h. These reference typical highway driving speeds and commercial jet aircraft cruising speeds. However, actual travel time can vary significantly depending on various factors. For cars, traffic conditions, road conditions, traffic lights, and rest stops affect travel time. For aircraft, takeoff/landing times, airport waiting, and wind effects (especially jet streams) influence actual flight duration. Therefore, the times provided here are for reference only, and it's advisable to check more specific information when planning actual trips.