Transformers, being extraterrestrials, are often overheard stating measurements in units that are unfamiliar to humans. Further, Transformers in different universes often use different units for measurement, and sometimes even use the same unit name but define it differently. Following is a list of units of time that Cybertronians have been observed using.
Roughly equivalent to an hour. In "The Magnificent Six!", Megadeath let his broken Autobot prisoners go with a neutronic blast imminent in two groons. Retelling this event to Silverbolt in 1990, Jazz described the time as two hours.
Used idiomatically like "hour", but of unknown duration. In "The Magnificent Six!", Steamhammer had an inspection parade scheduled at 0700 joors, not long after Cybertron's lunar dawn.
Generation One cartoon
Defined by Dreamwave's More Than Meets The Eye #8 as 1/1000th of a breem. Astroseconds as referenced in the Generation One cartoon seem to be much shorter, but were never defined. In particular, in "Divide and Conquer" Shockwave states that the space bridge will materialize within 72 billion astroseconds, an interval exceeding a millennium if Dreamwave's definition is applied. Even ignoring this extreme case, astroseconds in general cartoon use appeared to be much less than one second each.
As with the Beast Wars cycle, this unit is on the order of a second, as defined by the series' story editors. Used similarly in IDW comics.
A unit of undetermined duration. It was often mentioned since Episode 6 in Beast Wars cartoon.
Beast Wars cartoon story editors Bob Forward and Larry DiTillio stated that the "cycles" used in their series were very roughly equivalent to a minute. Maybe more, maybe less, but something of that order of magnitude.
As with the Beast Wars cycle, this unit is on the order of an hour, as defined by the series' story editors. Used incongruously in "The Agenda (Part 1)" to refer to a much longer span of time. (One of the Tripredacus Council says, "His ship and the Axalon both vanished last megacycle. The Maximal probes never found them.") Ben Yee cites a statement from DiTillio that another unit—the deca-cycle—is roughly year-like in length. This may be the unit that was intended for that line of dialogue.
DiTillio volunteers that Cybertron's rotational period (a "day") is ~20 hours.
Solar cycle (Beast Machines)
In the Beast Machines episode "The Weak Component", Rattrap uses the term "half a solar cycle" to describe the amount of time the Maximal would leave Megatron alone in order to regain his strength: one night, from dusk-to-dawn.
As with the Beast Wars cycle, this unit is on the order of a year, as defined by the series's story editors.
Orbital period (a Cybertronian "year") for Cybertron as stated by Larry DiTillio in information sent to Ben Yee.
In "Home Is Where the Spark Is", Optimus Prime enters Prowl's quarters asking, "Prowl, got a nanoclick?" Also, in "Fistful of Energon" Lockdown tells Prowl to "Wait a nanoclick." Idiomatically, then, this nanoclick is similar to either the English unit "second" or "minute", although its actual length is unknown. (The spelling of this unit comes from closed captions and differs from the Beast Wars spelling.) It is likely that it means second though, as in Nanosec Ratchet said the destronium would explode in 30 Nanokliks, and the urgency of his statement indicates a short period of time.
In "Rise of the Constructicons", Bumblebee asks Prime if he can take a coolant break. Prime responds that he just had a break "two cycles ago". From this it sounds as if a cycle is relatively short -- less than a day, certainly -- but its actual duration is unclear. In "Black Friday", Prowl challenges Bumblebee to stay quiet for "ten cycles", and he talks 30 to 40 seconds later. Prowl then informs Bumblebee that he managed to stay quiet for "barely half a cycle", implying that it is close to a minute.
In "Fistful of Energon", Ultra Magnus calls to report that Starscream has escaped. He says that it happened "a decacycle ago", and that he would have called sooner but their tachyon transmitter was missing. (The spelling, without a hyphen, comes from closed captions and differs from the Beast Wars spelling.)
~1 day or ~1 hour
In "Lost and Found" Ratchet estimated that it would take 10 mega-cycles to repair the Autobots' ship even with the help of the Key. The Autobots seemed to consider this to be a moderately long time, but not so long for it to be unrealistic that they might repair the ship before the Decepticons come at them in force. Later, in "Rise of the Constructicons", Bulkhead defends the Constructicons' behavior, asserting that "they've been online two, three megacycles tops." Thus, the megacycle may be daylike in duration, but this is quite uncertain. (The spelling, without a hyphen, comes from closed captioning and differs from the Beast Wars spelling.)
In the Transformers Animated premiere, "Transform and Roll Out!", several references are made to the Great Wars ending "centuries ago", all prior to first contact between Transformers and Earth. This is probably a case of dialogue being written for human observers rather than indicating the existence of a "Cybertronian century", but it is included here for completeness. Similarly, the history video at the very beginning of the episode refers to "millions of years", an Earth unit. It is unclear how this time should be interpreted. Starscream also refers to the search for the All Spark as lasting "centuries", which is at odds with Megatron's own statement that it has been "four million solar cycles" (see below).
In A Bridge Too Close, Part I, Starscream, after hearing all his clones, mutters to himself: "This is going to be a LONG orbital cycle", in reference to the phrase: "This is going to be a LONG day."
In "Transform and Roll Out!, Part 1", Megatron says he has spent "the last four million solar cycles searching the galaxy" for the All Spark. The parallel to Generation One's famous "four million years" implies that this unit is meant to be year-like. In "Part 3" Starscream refers to the 50-years of searching between the battle where "he defeated Megatron" and the present as 50 solar cycles, cementing this definition. In "Part 2", Optimus Prime and Ratchet have an exchange in which they use "solar cycle" in a way that is a better idiomatic match for "day" than "year", but, "year" can still work in that case. ("Stellar cycle" has also been used, but appears to be the same unit; see below.)
In the Animated episode "Along Came a Spider", Blackarachnia says that her accident occurred "a thousand stellar cycles" ago. Further, in "Megatron Rising - Part II" Megatron refers to both "fifty stellar cycles" and "four million stellar cycles", synching up with previous references to solar cycles. Thus, stellar cycle is apparently synonomous with solar cycle in this continuity. It is possible that while solar cycles refer to a unit of time based on a planet's rotation around the sun, a stellar cycle is a roughly equivalent universal standard used by the Transformers, who inhabit multiple planets with doubtless varying solar years.
The names of the units used in more than one continuity are: