Altitude Converter – Meters, Feet, Kilometers, Miles, Nautical Miles & Flight Levels
The Altitude Converter lets you instantly convert altitude and elevation values between six units used across aviation, geography, meteorology, mountaineering, and engineering: meters (m), feet (ft), kilometers (km), miles (mi), nautical miles (NM), and aviation Flight Levels (FL). Whether you are a pilot reading a METAR weather report in knots and feet, a hiker comparing mountain elevations in meters and feet, or an engineer processing GPS data in multiple coordinate systems, this tool eliminates the manual arithmetic and reduces unit-conversion errors.
What Units Does the Converter Support?
Six altitude units are supported, covering every major system in use today:
- Meters (m) — the SI base unit for length and altitude, used by most countries for geographic elevation and scientific measurement.
- Feet (ft) — the primary unit in aviation worldwide (even in metric countries) and the standard for elevation maps in the United States.
- Kilometers (km) — convenient for very large altitudes such as satellite orbits or atmospheric layers; 1 km = 1,000 m exactly.
- Miles (mi) — the statute mile used in the UK and US for terrestrial distances; 1 mile = 1,609.344 m exactly.
- Nautical Miles (NM) — adopted by aviation and maritime navigation; 1 NM = 1,852 m exactly. Nautical miles are sometimes used for altitude-based separation calculations.
- Flight Level (FL) — an aviation-specific unit where 1 FL = 100 feet of pressure altitude. FL350 corresponds to 35,000 ft or 10,668 m.
How Altitude Conversions Are Calculated
All conversions use meters as the intermediate base unit. The input value is first multiplied by the factor that converts the source unit to meters, then divided by the factor for the target unit. The conversion factors are exact international definitions:
1 ft = 0.3048 m(exact)1 km = 1,000 m(exact)1 mi = 1,609.344 m(exact)1 NM = 1,852 m(exact)1 FL = 100 ft = 30.48 m
For example, to convert 10,000 feet to meters: 10,000 × 0.3048 = 3,048 m. To convert FL350 to meters: 350 × 30.48 = 10,668 m.
Aviation Flight Levels Explained
A Flight Level (FL) is a standardised pressure-altitude reference used by pilots and air traffic controllers worldwide. It equals 100 feet of pressure altitude, measured from the International Standard Atmosphere (ISA) sea-level datum of 1013.25 hPa (29.92 in Hg). Because all aircraft use the same reference pressure, Flight Levels ensure uniform vertical separation even when local barometric pressure varies. Common cruising Flight Levels range from FL280 (28,000 ft) to FL430 (43,000 ft) for commercial jets. The Altitude Converter treats FL as a linear unit: simply multiply the FL number by 100 to get feet, or by 30.48 to get meters.
Negative Altitudes – Below Sea Level
The converter accepts negative values, which represent altitudes below mean sea level (AMSL). Notable below-sea-level locations include:
- Dead Sea shoreline: approximately −430 m (−1,411 ft)
- Mariana Trench deepest point: approximately −11,034 m (−36,201 ft)
- Below-ground mining operations, underground caves, and tunnels
Altitude vs. Elevation vs. Height
In practice, the terms are used interchangeably but carry specific meanings in technical contexts. Elevation refers to the height of a fixed point on the Earth's surface above a reference datum (usually sea level). Altitude is the vertical distance of a moving object — typically an aircraft — above a datum. Height usually refers to the distance above the ground directly below (AGL, Above Ground Level), as opposed to above sea level (AMSL). This converter performs unit conversions only; it does not perform datum corrections between AMSL, AGL, or WGS84 ellipsoid heights.
Practical Use Cases
The Altitude Converter is useful across many fields:
- Aviation: Converting METAR/TAF altimeter settings and cruising altitudes between feet and meters; translating Flight Levels to standard metric values for international flights.
- Mountaineering and hiking: Comparing peak elevations between metric and imperial sources — for example, Mount Everest at 8,848 m vs. 29,031 ft.
- Meteorology: Weather balloon sounding data is often provided in meters or feet at different altitudes; converting between them is routine.
- Engineering and surveying: GPS receivers output ellipsoid heights in meters; converting to feet is necessary for US construction projects.
- Aerospace: Satellite orbital altitudes are typically in kilometers; the converter lets you express them in nautical miles or feet for mission-planning comparisons.
Batch Conversion for Multiple Values
When processing flight logs, survey datasets, or weather sounding data, you may need to convert many altitude values at once. The batch conversion feature accepts a list of numbers separated by commas or newlines and converts them all using the same selected unit pair. Invalid entries are flagged individually without blocking valid conversions, so you can identify and correct data errors efficiently.
Tips for Accurate Altitude Conversion
Use the precision slider to set the number of decimal places (0–10) appropriate for your application. Aviation operations typically use 0–1 decimal places (feet are integers on most instruments), while scientific and survey applications may require 4–6 decimal places. Use the all-units summary table to see your value expressed in every supported unit simultaneously, which is particularly useful when comparing data from different sources.