The Earth Similarity Index uses both Mass and Radius as criteria.

The maximum value for the Earth Similarity Index was 1.00 - for Earth, unsurprisingly.

Kepler-62f is most likely a terrestrial planet within the outer part of its host star's habitable zone and has an Earth Similarity Index of 0.69.

If its existence is confirmed it could be the most Earth-like planet yet at 99% ESI (Earth Similarity Index).

The Earth Similarity Index, ESI or "easy scale" is a measure of how physically similar a planetary mass object is to Earth.

It topped the Earth Similarity Index, while Saturn's moon Titan ranked highest in the Planet Habitability Index.

In their paper, the authors propose two different indices: an Earth Similarity Index (ESI) and a Planetary Habitability Index (PHI).

It is notable due to its predicted habitability and Earth-like properties, with an Earth Similarity Index of 0.71 and an orbit that places it in Tau Ceti's extended habitable zone.

NASA and the SETI Institute now categorise Earth like planets using an Earth Similarity Index (ESI) based on mass, radius and temperature.

With an increase in the intensity of exoplanet discovery, the Earth Similarity Index (ESI) was devised in October 2011 as a way of comparing planetary properties, such as surface temperature and density, to those of the Earth in order to better gauge the habitability of extrasolar bodies.