Credit to the Halo Wiki, here is the page where this information comes from
Sometimes the Kardashev Scale is not enough to quantify a civilization, that is why the Forerunners made a handy scale when that happens. It measures a civilization by what they achieve.
This scale has been slightly edited so it is more applicable to other sci-fi verses. So Slipspace travel now counts as warp drives, hyper space, or anything similar to that.
Also note that there might be some confliction with tier 1&0. As tier 0 implies abandoning common tech, and using non physical tech. But this might be a problem as for example, the Time Lords far exceed the Precursors, but they use tangible technology, so they would only be tier 1.
Tier 7: Pre-Industrial
Tier 7 is one of the most common and stable states, with limited weaponry and environmental threats. Societies tend to be small and scattered, driven by subsistence farming, foraging, or hunter-gathering needs. Technology is limited to simple hand made tools, weapons, or agrarian implements and methods, but a very broad understanding of planetary and solar mechanics is not uncommon.
Tier 6: Industrial Age
Tier 6 is the outset for massive urbanization. Agrarian societies can remain stable in the pre-industrial stage, but Tier 6 population strain and mechanized food production invariably create political and economic pressures very few can balance. Moving past this usually promises advancement. Some societies improve environmental and medical understanding concurrently with mechanical and transport advancement. Those that do not are frequently doomed.
Humanity entered this Tier in 1781 with the advent of steam technology.
Tier 5: Atomic Age
Tier 5 species usually begin focusing on clean energy production. The occasional belligerent species will use atomic energy for weapons, often resulting in mass extinctions. In-atmosphere craft are a hallmark, often leading to manned space flight, albeit on a short-scale.
Humanity entered this age in 1945, when the atomic bombs were deployed, and manned space travel was accomplished for the first time in 1961.
Tier 4: Space Age
Tier 4 is often the final resting place for species intelligent enough to break free from their cradle's surface only to fill the gulf surrounding it with war. Their comfort-focused technology can include medical advances.
Humanity reached this level in 1957, when the first artificial satellite was launched.
Tier 3: Space-Faring
The species in this tier have efficient FTL space travel navigation, advanced mass driver tech, and AIs . They have had no outside influence.
Tier 2: Interstellar
The species has the ability to perform exceedingly accurate FTL space travel navigation, pinpoint accurate communications, and man-portable application of energy manipulation.
Tier 1: World Builders
The species has the ability to manipulate gravitational forces, create advanced AI, fabricate super-dense materials, perform super-accurate FTL space travel navigation, the ability to create life, and the ability to create worlds
Tier 0: Transsentient
This is a theoretical ceiling. It is suspected that they can travel across galaxies and accelerate the evolution of intelligent life. Along with this the use of exotic technologies such as neural physics and time travel is suggested at this stage.