The mean orbital velocity needed to maintain a stable low Earth orbit is about 7.8 km/s (28,000 km/h; 17,000 mph), but reduces with increased orbital altitude. Calculated for circular orbit of 200 km (120 mi) it is 7.79 km/s (28,000 km/h; 17,400 mph), and for 1,500 km (930 mi) it is 7.12 km/s (25,600 km/h; 15,900 mph). The delta-v needed to achieve low Earth orbit starts around 9.4 km/s. Atmospheric and gravity drag associated with launch typically adds 1.3–1.8 km/s (4,700–6,500 km/h; 2,900–4,000 mph) to the launch vehicle delta-v required to reach normal LEO orbital velocity of around 7.8 km/s (28,080 km/h; 17,448 mph).
The pull of gravity in LEO is only slightly less than on the Earth's surface. This is because the distance to LEO from the Earth's surface is far less than the Earth's radius. However, an object in orbit is, by definition, in free fall, since there is no force holding it up. As a result objects in orbit, including people, experience a sense of weightlessness, even though they are not actually without weight.
Objects in LEO encounter atmospheric drag from gases in the thermosphere (approximately 80–500 km above the surface) or exosphere (approximately 500 km or 311 mi and up), depending on orbit height. Due to atmospheric drag, satellites do not usually orbit below 300 km (190 mi). Objects in LEO orbit Earth between the denser part of the atmosphere and below the inner Van Allen radiation belt.
Equatorial low Earth orbits (ELEO) are a subset of LEO. These orbits, with low inclination to the Equator, allow rapid revisit times and have the lowest delta-v requirement (i.e., fuel spent) of any orbit. Orbits with a high inclination angle to the equator are usually called polar orbits.
Higher orbits include medium Earth orbit (MEO), sometimes called intermediate circular orbit (ICO), and further above, geostationary orbit (GEO). Orbits higher than low orbit can lead to early failure of electronic components due to intense radiation and charge accumulation.
In 2017, a very low-Earth orbit (or very-low LEO orbit) began to be seen in regulatory filings. This orbit, referred to as "VLEO", requires the use of novel technologies for orbit raising because they operate in orbits that would ordinarily decay too soon to be economically useful.