Reading from fluff, Ascension literature, and other FFG based literature, I have devised a chart converting the standard Games Workshop Greek alphabet-derived Psy Rating Assignment Chart with the FFG's Dark Heresy/Rogue Trader/Deathwatch numerical-derived Psy Ratings:

Behold-

From the psy inert to the towers of psionic might

Omega- Blanks. Untouchables. Culexus. (complete immunity, -20 fellowship)

upsilon phi chi psi- basic immunity (+20 to resist, double toughness vs psy power, -10 fellowship)

sigma tau- psy density (does not sense psyker powers, +10 to resist, -5 fel)

=======
rho pi -no power
=======

omicron xi nu mu lambda kappa- immeasurably low levels of power

iota- 1
theta- 2-3
eta- 4-5

zeta 6-7
epsilon 8-9
delta 10-11
gamma 12-13
beta 13-14
alpha 14+

In game terms, "Medicae Imperialis discussion agrees that current human beings do not possess the necessary evolutionary development to contain Beta and Alpha levels of psionic talent. As such, the great majority of those discovered at this Assignment rating usually suffer from mental instability."

Perhaps 15 points of insanity /rank over threshold.

NewAgeOfPower said:

This would then be a houserule. It is not given in the normal DH-rules.

Noctus said:

And a really bad one since it makes a High level Primaris Psyker next to impossible to play since, without anything else he will have 45 more insanity.

It iIS just a house rule. You are right, its a little too harsh.

This is just a chart attempting to match fluff.

Fairly early on after the release of Dark Heresy, I had a go at reconciling the DH psyker grades with the previously published Alpha-Zeta system mentioned in the "Inquisition" sourcebook and the Dan Abnett novels. I drafted it up and emailed it through to TS Luikart, who designed the original psyker rules for Dark Heresy. He was kind enough to reply to my draft, which was really good of him. He didn't entirely agree with everything I'd written, so I amended the article to summarise where the two of us differed so people could decide which version they preferred. Here it is again:-

Psyker Grades (By TS Luikart & Lightbringer)

Legend holds that the Emperor himself designed the terms by which the Imperium grades potential psychic strength using an ancient system. The following gradations are designated in one of the truly ancient languages of Holy Terra in order of ascending power levels. None of the grades are meant to be an exacting mark of ability, but rather, of raw power.

These designations tend to be as fluid as the psykers themselves are, and there is a wide variation of power within each grade – a well-trained psyker of a lesser grade has a decent chance of beating a stronger, untrained psyker and is far less likely to become warp tainted. Note that there are many lesser grades of psychic ability than Zeta, but they are all but undetectable without the most sophisticated of equipment. Humans without noticeable psychic ability are usually referred to as Baseline, Pure, Blunt, or Dim, the last term being an insulting reference to how they appear to psykers when viewed in the warp. Humans with absolutely no psychic ability as well as those who have a negative effect on the Immaterium are referred to as Untouchables.

Zeta Grade – The most common grade in the Imperium with a readily noticeable level of ability, Zeta Grade psykers tend to have a few minor psychic powers at most, which they may or may not be able to employ in a haphazard fashion. The weakest of the common grades and therefore the most dangerous, Zeta Grade psykers are frequently a beacon to daemons. Their mere existence is a liability to all about them and they make up the majority of those psykers rounded up by the Adeptus Arbites and the Inquisition, as psykers weaker than Zeta Grade can often slip by unnoticed by the authorities, or indeed, seldom have any idea that they are psykers. A considerable number of mutants have Zeta Grade psychic ability. With rigorous training, a high end Zeta Grade psyker may aspire to being an Epsilon but only a few have the will to endure the trials required without loosing their sanity and few Imperial authorities would waste their time attempting to salvage them.

Game Mechanic: To be rated as a Zeta Grade Psyker, you must possess the Dark Heresy Psy Rating 1 talent, and have at least 1 minor psychic power.

Epsilon Grade – The first grade with enough power to allow for structured ability, Epsilon Grade psykers can consistently invoke several minor powers and have begun to grasp the fundamentals of one of the Psychic Disciplines. A large number of the rogue psykers known as Wyrds are Epsilon Grade. Sufficient time, training and will can allow a powerful Epsilon into a Delta, giving them the ability to learn more powers within their Discipline.

Lightbringer’s Game Mechanic: To be rated as an Epsilon Grade Psyker, you must possess the Dark Heresy Psy Rating talent grade 3, have selected one discipline and have one power from that discipline. You must also have also have at least 4 minor psychic powers. If you fail to meet all of these requirements, you are a Zeta grade psyker.

TS Luikart’s Game Mechanic: To be rated as an Epsilon Grade Psyker, you must possess the Dark Heresy Psy Rating talent grade 3, have selected one discipline and have one power from that discipline. If you have the Talent Power Well or Discipline Focus, you are likely considered an Epsilon+ and close to being a Delta. If you have neither, you are regarded as either a Zeta+ or a low tier Epsilon at best.

Delta Grade – The bulk of Imperial psykers fall into the low end of this category. Delta Grade psykers have frequently mastered a single Psychic Discipline and the more powerful are usually capable of utilizing portions of a second. The majority of common Astropaths are Delta Grade, as are a fair number of battlefield ready Imperial Guard psykers. Well-trained Delta Grade psykers are very dangerous individuals, capable of utilizing their abilities to the fullest. Time and discipline may well see a Delta eventually achieving Gamma Grade, if they neither die nor burn out their abilities before then.

Lightbringer’s Game Mechanic: To be rated as a Delta Grade Psyker, you must possess the Dark Heresy Psy Rating talent grade 4, have at least 6 minor powers, 5 psychic powers from 1 discipline and at least 1 power from a second psychic discipline. If you fail to meet all of these requirements, you are a Zeta or Epsilon grade psyker.

TS Luikart’s Game Mechanic: To be rated as a Delta Grade Psyker, you must possess at least the Dark Heresy Psy Rating talent grade 4. You also must have either 7 psychic powers from 1 Discipline, or a combination of 5 from 2 Disciplines. You must have either Power Well or Discipline Focus. If you have powers but not the appropriate Talents, you are likely deemed a low level Delta. If you have both, you are likely regarded as a Delta+ or possibly a low level Gamma - especially if you have a Psy Rating 5.

Gamma Grade – Powerful psykers with iron hard wills, Gamma Grade psykers are among the most elite the Imperium has to offer. Often deft users of two Psychic Disciplines and frequently capable of using powers from several others, Gamma Grade psykers are versatile and deadly foes. The majority of psykers will never progress beyond this point, often because they see no need to do so. Navigators are frequently considered to be Gamma Grade in raw power, though their actually breadth of abilities is lesser than a well trained Gamma would typically have. An incredibly driven and strong willed Gamma could aspire to Beta Grade, but it would literally take decades to achieve.

Lightbringer’s Game Mechanic: To be rated as a Gamma Grade Psyker, you must possess the Dark Heresy Psy Rating talent grade 6, and have at least 1 psychic power in each of 3 separate disciplines. If you fail to meet all of these requirements, you are a Zeta, Epsilon or Gamma grade psyker as appropriate.

TS Luikart’s Game Mechanic:- To be rated as a Gamma Grade Psyker you must possess at least the Dark Heresy Psy Rating Talent grade 5 and have both the Talents Power Well and Discipline Focus. You must also be either the Master of a single Psychic Discipline, e.g. 10 powers (or more) or you must have 7 Discipline Powers from two or more Disciplines. If you have the bulk of the requirements, only lacking say 1 power, you are likely rated as a low level Gamma. If you have a Psy Rating 6 with the above, you are likely regarded as a Gamma+ or a low level Beta.

Beta Grade – Psykers of the Beta Grade are frequently born, not made, as the raw power that typically indicates this level of ability is almost impossible to achieve with training alone. Many Betas therefore start with only a single Psychic Discipline, though they can usually invoke their various powers with near ludicrous ease and control. The rare Beta Grade psykers who have reached this level through training and discipline are frighteningly powerful individuals who invariably have a wide variety of Psychic Disciplines and individual abilities to draw upon. They usually have a century or more of experience in applying said abilities in a myriad of ways making them phenomenally dangerous combatants. A number of the more powerful members of the Inquisition as well as the bulk of the Librarians of the Adeptus Astartes are Beta Grade psykers.

Lightbringer’s game mechanic: Beyond the current scope of Dark Heresy game mechanics.

TS Luikart’s Game mechanic: A psyker that greatly exceeds all of the requirements for Gamma may be deemed a low level Beta. Mid-tier and high level Betas have ability potentials not yet covered by Dark Heresy game mechanics.

Alpha Grade – This level of ability cannot be reached through training; only a will of adamant or accident of birth allows a psyker to achieve Alpha Grade. Alpha Grade psykers are among the most powerful in existence, having far superseded anything that any teacher could’ve taught them. Even the strongest Imperial psykers seldom reach this pinnacle of ability, as such a profound connection to the warp would drive the majority of psykers insane. While it has never been conclusively proven, Imperial thought is that only centuries of careful discipline and rigid self control can ever allow a human (or once-human) mind to successfully achieve Alpha Grade without warp corruption; a theory backed by the simple fact that every Alpha Grade Imperial psyker on record has inevitably been either a Master Librarian of the Adeptus Astartes or an ancient Inquisitor Lord.

TS & Lightbringer: These psykers are beyond the current scope of Dark Heresy game mechanics. (NB - we wrote this part in 2008-2009, so arguably there are now mechanics that can cover Alpha Psykers)

Alpha-Plus Grade –This classification exists for any psyker whose powers are so far beyond the norm as to be immeasurable by Imperial science. Near god-like in ability, Alpha-Plus Grade psykers are almost invariably warp corrupted and insane. Their powers are nearly unimaginable in scope, e.g. Telepaths capable of controlling the populations of entire planets, Telekines strong enough to crush a Battle Titan with a thought, etc. The Imperium’s policy on all Alpha-Plus Grade psykers is typically immediate termination, though this is easier to state then to achieve.

TS & Lightbringer:- Alpha+ - Walking plot devices - presently waaaay beyond the scope of released Dark Heresy game mechanics.

TS Luikart’s comments on the grading system:
First off, none of the "levels" are absolutes. A psyker that dedicates himself to taking the most direct road to power, e.g. Talents like Power Well and Discipline Focus, would generally rank higher than one that doesn't. The Scholastica Psykana tends to put greater emphasis on "Mastery" over "breadth of knowledge" and regard the Master of a single Discipline better than a "dilettante" who has powers from several Disciplines but hasn't mastered any. Minor powers no matter how useful are in general beneath the Psykana's contempt if you truly wish to be considered a powerful psyker

By the way, my own perception of the "Alpha-Zeta" scale is that it is a bit like the Richter scale: popularly used by laymen, but hardly used at all by the experts, the psykers themselves.

Seismologists prefer the moment magnitude scale, because it's more nuanced and detailed, and the press prefer the Richter scale because it's simple and sounds impressive. Sanctioned psykers almost certainly use a variety of alternative rating methods.

It's also worth bearing in mind that the Dark Heresy scheme is a game mechanic, not a background feature, so there will never be a complete alignment between the two.

Nevertheless, it is quite cool to be able to say "I'm a Gamma level psyker!"

I made my own diagram to explain it to our psyker player.

the describtions are based in the inquisition sourcebook as others have mention and the Psy-rating scaled to the characters in-game (max psy-rating (10) while reamaining sane is Beta, Alpha+ is 14 as seen with the Burning Princess etc.)

Note: that this include the entire theoretical scale far beyond what is possible in-game. the scale is only used to measure the basic potential and does not take the "Pushing" mechanic into account.

Rating In-Game Additional Notes

Omega + PR: 40 Highest theoretically scale. Hypothetically impossible, The Power of Gods
Psi + PR: 38-39
Chi + PR: 36-37
Phi + PR: 34-35
Upsilon + PR: 33
Tau + PR: 32
Sigma + PR: 31
Rho + PR: 30
Pi + PR: 29
Omicron + PR: 28
Xi + PR: 27
Nu + PR: 26
Mu + PR: 25
Lambda + PR: 24
Kappa + PR: 23
Iota + PR: 22
Theta + PR: 21
Eta + PR: 20 A being with a psychic talent of this scale would become a non-corporeal entity
Zeta + PR: 19 Highest theoretically psychic rating possible in an corporeal body
Epsilon + PR: 18
Delta + PR: 17
Gamma + PR: 16 Highest Psy-rating ever observed
Beta + PR: 15
Alpha + PR: 14 A human psyker with a rating of Alpha Plus or above is without exception insane

Alpha PR: 12-13 on pair with Untouchables in rarity
Beta PR: 10-11 Beta is the highest rating a human mind can achieve and remain sane
Gamma PR: 8-9
Delta PR: 6-7 Delta and higher are designated “Master-level psykers” these are usually found once per billion
Epsilon PR: 5
Zeta PR: 4 Zeta and higher indicates a very powerful psychic manifestation
Eta PR: 3
Theta PR: 2 Above Iota the power and rarity increases exponentially for each level
Iota PR: 1 Iota and above represent active psi-ability of some degree (Ca. once per 10.000th)
Kappa PR: 0.8-9 Upper-limit of low activity, usually also the level where the ability can be detected
Lambda PR: 0.6-7
Mu PR: 0.4-5
Nu PR: 0.3
Xi PR: 0.2 Omicron to Kappa is theoretically found approximately once in every thousand
Omicron PR: 0.1 Lowest psychic level (Omicron to Kappa), usually unknown to the bearer
Pi PR: 0 Upper-limit of none psychic-active sentience, slightly more sensitive
Rho PR: 0 Standard human baseline psychic activity (99.9%)
Sigma +5 to resist* Blunt individuals who are even less sensitive to psychic phenomena than normal
Tau +10 to resist*
Upsilon +15 to resist* Severely “Blunt-minded” individual who can barely feel psychic energy at all
Phi +20 to resist*
Chi +25 to resist* Individuals so “Blunt” that they practically cannot feel psychic energy
Psi +30 to resist*
Omega PR: -5 Untouchable, negative psychic presence (Approx. less than once every billion).

Omega – PR: -6/-7 Information concerning Reverse Scale individuals are only known to Ordo Sicarius
Psi – PR: -8
Chi – PR: -9
Phi – PR: -10
Upsilon – PR: -11
Tau – PR: -12
Sigma – PR: -13
Rho – PR: -14
Pi – PR: -15
Omicron – PR: -16
Xi – PR: -17
Nu – PR: -18
Mu – PR: -19
Lambda – PR: -20
Kappa – PR: -21
Iota – PR: -22
Theta – PR: -23
Eta – PR: -24
Zeta – PR: -25
Epsilon – PR: -26
Delta – PR: -27
Gamma – PR: -28
Beta – PR: -29
Alpha – PR: -30 Lowest theoretically scale. Hypothetically impossible, The Stuff of Nightmares

*Willpower Tests to resist mental psychic powers only, no immunity to physical powers or Daemonic possession

Heh, that doesn't seem to go very well with the description of PR 5 or 6 in the DH core book, does it? It basically states that at 6 you are among the premier human psykers alive. Ah well, "greatest human potential" isn't what it used to be . By the way, what PR were farseers again? I think one was statted in one adventure.

The_Shaman said:

Well to be fair that was writen before we got Alpha Plus level with PR 14 and ascension raised the bar to 9-10 for all primaris psykers.

A Farseer's psy-rating lies at 8 according to Rogue Trader: Lure of the Expanse. Which also holds true for Hive Tyrants and Greater Daemons of Tzeentch all three of which however also have a very high willpower with the benefits of unnatural Willpower which also helps a great deal.

Well, the "fact" that a human psyker is supposed to be practically orders of magnitude more powerful (even if poorer at controlling it) than a hive tyrant, greater daemon of Tzeentch , or a farseer with centuries of experience... Eh, it strikes me as weird, frankly.

You are right, this make other races in 40K ordinary monsters as in D&D, this is bad, because in 40K every race has her own plans.

In RPGs the Groups tend to bring in the Once in a billion type of chars. And in DH more likely the once in a trillion. A Alpha + Psyker may be much more powerful then a Eldar Farseer, but whom of both do you think will endure the next say ten years? There are some exceptional humans, extremely extremely rare wich might burn hot like a Nova, but also they burn short. A Farseer will gain something of his Psyrating 8 for quite some time while a ordinary Human Primaris psyker might not even live to the rest of the year.

I dont think its entirely needed that some extremely powerful Monsters have Ultrahigh Psyratings. The Tzeentch Daemon maybe, but a Hive Tyrant is also a fearsome fighter besides his Psyrating and a Farseer is someone who enjoys his talents savely for a thousand years. Just because something is possible within the rulesystem of a RPG doesnt say that this is something ordinary. And that the IoM will bring forth some truly powerful Psykers, even compared to Eldar is just a freak chance of statistics. After all therre are one or two more humans then eldar...

And if the Psyrating 10 Human want to use his powers as safely then the literature Farseer does this he has to use his powers fettered which gives him an effective Psyrating of 5.

The psy-rating for the xenos and daemons are at those points also so that it is possible for the payers to defeat them. the Greater Daemon pf Tzeentch can have its Psy-rating boosted to 10 and have access to every Singel psychic power in the game if you give it that special gift of Tzeentch and if you want a more powerful farseer in the gamer simply give him/her a higher psy-rating, it is not that difficult.

Which brings me onto other questions, now you got this range for Human Psykers, what would be the RANGE for Xeno's psykers? For the Eldar, if a Farseer's average is 8 what is the upper limit, what would a warlock be, would all Eldar be >0? If all Orks are to a degree psychic are they all >0. What is the range for lesser and greater Daemons?

I'd be cautious about using the game mechanic psy-rating figure alone as a guide to the setting-specific psychic rating under the Alpha/Beta/Gamma scheme. I'm just basing this on TS Luikart's comments about how pure psychic "horsepower" isn't the only measure of psychic ability for the purposes of the latter scheme..

I know that his comments were written a couple of years back, and that there have been many further developments in the RPG since, but his approach fits in well with the setting, where a skilled and imaginative psyker with a wide range of abilities can still defeat a psyker with a greater level of inherent psychic strength.

Lightbringer said:

Agreed.

the list I created is only used as a indicator to give a rough estimate of a psyker's strength, while dozens od other factors also play in, it is a bit like saying that one car is better than another purely by judging how fast it car drive. okay perhaps a bad examble but I think I get your point

I myself favor a simple "Can the psyker smash/melt a Battle Titan in one round? Then its an alpha psyker." philosophy. Most primaris psykers from DH Ascension easily qualify as alphas.

Easyly? You have to cause 242 points of damage to kill a Warhound titan in one Round. Even with Firestorm you cant cause this much damage in one Round.

I was MILDLY exaggerating, as it actually takes TWO rounds for a primaris psyker to kill a battle titan with their giant firestorms... though on average, a primaris psyker will still kill a battle titan in one round using Holocaust, especially if he attacks with Psychic Blade or something as well.