Vigor = 40/58
Mind = 40/50 (38 if you want only as much FP as a max upgraded Flask will restore)
Endurance = 25/40/50/60
Strength / Dexterity = 20/53/80 (STR only: 35/53 if 2Handed)
Intelligence / Faith / Arcane = 20/50/80 (for attack power)

Casting Scaling = 60/80 for most single-stat catalysts
Casting Scaling = 30/45 for most multi-stat catalysts

Stat breakpoints are not always intuitive; many people think 40 and 60 are the default points at which diminishing returns start in all souls-like games, but the data is more complex than that. For instance, just look at my guide for Dark Souls 3 where the breakpoints for Vigor were 17/26/44
https://steamoss.com/sharedfiles/filedetails/?id=672914215

Elden Ring handles some stats a little wierdly; often times the benefits ramp up such that the first point you put in gives you very little but each additional point gives more and more... up to a cutoff. Thus you generally want a stat either as low as possible or directly at the breakpoint with anything in-between costing you value. That makes classes with the LOWEST starting stats in things you do NOT want, the most valuable to a min/maxer. For class starting stats please refer to the Elden Ring Wiki[eldenring.fandom.com] and keep in mind; even with respecs, you can't go below the lowest value allowed by your class, so a Wretch is stuck at a min of 10 while eg a Vagabond can take Arcane down to 7

Why should you trust what I say over anyone else?
Because I always offer you access to the raw data for you to see for yourself.
Which is available here.[www.dropbox.com] (This data was recorded with v1.02 of Elden Ring)
Keep in mind; each level gives a baseline bonus to Physical/Magic/Fire/Lightning/Holy/Immunity/Robustness/Focus/Vitality, the table shows the ADDITIONAL increase to these, over-top that baseline. Which is why I label them eg "Focus+"

My methodology for collecting this data is as follows. I started as a lvl 1 Wretch with 10s in all stats. I... "acquired" enough souls/runes to level one stat all the way up to 99, hand recording all the stat changes for each point, and then reset and repeated the process for each different stat. My character was completely naked for this to avoid any unwanted contributions.
To find casting power/damage; I again stripped naked but for a Finger Seal, and used the Grace at Warmaster's Shack to repeatedly trigger the nearby 3 wolf ambush. Using the Flame Sling, I recorded the damage done to these three wolves at each Faith level from 10 to 99. I've used this same location and technique for Intelligence (with Glintstone Pebble) and Arcane.

Since this information was hand recorded, there is always the possibility my finger slipped and eg hit a 2 instead of a 1 and I never noticed or something else like that, but since the raw data is available to all - you are perfectly free to rerun the experiment yourself and check the results. That said there is at least one error in this data on Fromsoft's side and not mine. Discovery from Arcane scales linearly; as in - one point in, one point out... except at 91 Arcane, then it gives you 2 points and then zero points for lvl 92 - this seems to me to be a clear mistake, but it is in the game so I record it. Not that it'll really affect anyone :-P

The hard cap for everything is 99 btw
Additionaly, Weapon+NUMBER does not actually change the scaling in anything I've tested so far.
It only applies a multiple to the bonuses thus leaving the breakpoints in the same places as +0

Vigor = 40/58
"Attribute governing HP - Your life. If reduced to nothing, you die.
Also affects fire resistance and immunity - Your resistance to various poisons and rot."
Hard decrease at 40, and very little benefit going from 58 to 60
Recommendation: Since HP gains ramp up there is no reason not to take Vigor to 40, but I wouldn't bother going to 58

Mind = 40/50
"Attribute that determines FP - Energy consumed to use spells and skills.
Also affects focus - Your resistance to sleep and bouts of madness."
Focus hits a hard decrease at 40, but FP actually continues to ramp up until 41 then diminishing returns really start after 50 (UPDATED to v1.04 changes)
Recommendation: If you use FP, then take Mind all the way to 50 imo, but some players disagree with me here. At least take it to 40

Endurance = 25/40/50/60
"Attribute governing stamina. Endurance determines how heavy your equipment can be.
Also affects robustness - Your resistance to blood loss and frostbite."
Stamina hard stops at 50, Equip Load has two stopping points at 25 and 60, and if you care about it - Robustness has a hard decrease at 40
(v1.04 didn't change as much for Endurance and Stamina; it really only introduced super soft diminishing returns after 15 and 30, but they are so soft I'm not even going to update the graph because you wouldn't be able to tell the difference. Check the raw data if you want to see it)
Recommendation: If you primarily cast, leave this at 25, otherwise take it to at least 30 if not higher but some players disagree with me here. Personally, as a stamina fiend, I wouldn't settle for anything less than 50

Strength = 20/~53/80 (35/53 if 2Handed)
Casting Damage = 30/45 (with Clawmark Seal or Frenzied Flame Seal)
"Attribute boosts attack power of strength-scaling armaments and affects your physical defense."
STR and DEX appear to be fairly heavily front loaded with your greatest gains coming in on the way to 20, the weapons I've tested are fuzzy on the 50 number with ranges of 51 to 53...
Since 2Handing a weapon multiplies your effective STR by 1.5x you could stop ~35.
Physical defense is fairly linear and diminishing returns really only start after 61
Recommendation: If you use it; take it to 20 asap, then focus on survivability/utility before coming back and making the push for 35/53, I do not think 80 is a worthwhile goal unless via 2Hands

Dexterity = 20/~53/80
Casting Damage = 30/45 (with Frenzied Flame Seal)
"Attribute boosts attack power of dexterity-scaling armaments, reduces casting time of spells, softens fall damage, and makes it harder to be knocked off your horse."
STR and DEX appear to be fairly heavily front loaded with your greatest gains coming in on the way to 20, with slower growth between 20 and ~53, and very little growth past that but yes it takes an even steeper decline after 80
I have no data on the rest of the tooltip information; to get numbers on casting speed - you'd have to have video capture capability and count the difference in individual frames between different DEX levels... which is not something I am capable of. If you want to tho, please do, I'd love to know the results
Recommendation: If you use it; take it to 20 asap, then focus on survivability/utility before coming back and making the push for 53, I do not think 80 is a worthwhile goal

Intelligence = 20
Attack Power = 20/50/80
Casting Damage = 30/45/60/80 (WARNING: different staves have different breakpoints)
"Attribute boosts magic power of intelligence-scaling sorceries and improves magic resistance."
At least for Magic resistance there is a hard decrease at 20
For weapon damage from INT/FTH scaling, these stats also appear to follow a 20/50/80 split.
Casting damage has many different breakpoints depending on which staff you are using. As an example the Demi-Human Queen's Staff only has breakpoints at 20/40. But as a general rule; any staff/seal which scales with two or more attributes will have 30/45 breakpoints, while a "pure" staff/seal will be at 60/80. The Prince of Death's Staff is the only "hybrid" option with scaling to 60/80
Recommendation: If you use it; take it to 20 asap, then focus on survivability/utility before coming back and making the push for 50/80 (if you are going in on a casting stat, go all in)

Faith
Attack Power = 20/50/80
Casting Damage = 30/45/60/80 (WARNING: different seals have different breakpoints)
"Attribute boosts magic power of faith-scaling incantations."
Attack power from weapons with INT/FTH scaling also appears to follow a 20/50/80 split.
As a general rule; any staff/seal which scales with two or more attributes will have 30/45 breakpoints, while a "pure" staff/seal will be at 60/80. The Prince of Death's Staff is the only "hybrid" option with scaling to 60/80
Recommendation: If you use it; take it to 20 asap, then focus on survivability/utility before coming back and making the push for 50/80 (if you are going in on a casting stat, go all in)

Arcane = 20/45
Attack Power = 20/~50/80
Casting Damage = 30/45 (with Albinauric Staff or Dragon Communion Seal)
"Attribute governing discovery - Likelihood of finding items on the corpses of defeated foes.
Also affects holy defense, certain sorceries and incantations, and vitality - Your resistance to instant death."
Like Intelligence, Holy resistance here has a hard decrease at 20 while Vitality shows softer decreases at 15 and 39; Discovery as mentioned previously is linear (mostly) all the way to 99.
Bleed buildup appears to plateau around 44 to 46, while attack power follows the 20/50/80 rule, however since arcane has no "pure" staff/seal, only "hybrid" ones, casting damage here has only 30/45 breakpoints
Recommendation: If you use it; take it to 20 asap, then focus on survivability/utility before coming back and making the push for ~45, I do not think 80 is a worthwhile goal

• Pick two attack stats; STR/FAITH, DEX/INT, STR/DEX, etc and push them both to 20 asap
  
• Then branch out, maybe push Endurance to 25, then Vigor and/or Mind to 40
  
• From there you could go deeper into an attack stat, or Endurance, pushing it to 50 (melee) or 80 (casting)

If you want to limit yourself to only as much FP as a max upgraded Flask will restore, then 38 Mind is where you want to stop now as of v1.04

I haven't tested it, but STR gives a 50% bonus when 2Handing a weapon which could save you a few levels since 35 x 1.5 = 52.5

Alternatively, if you are crazy like me, you could get Arcane to 20 first, then do everything else here (I wouldn't actually recommend that unless you really are investing in Arcane)

40 Vigor
30 Endurance (v1.04 made lower endurance more viable, but this is as low as I'd go)
35 Strength (2Handing makes this equal to 52.5)
20 Dexterity (next step can be DEX 53, or Arcane 45 if you want to make things bleed)
--------------
= Level 86
(81 with Hero or Vagabond, 82 with Samurai; Hero is best if you take any Arcane)

40 Vigor
40 Mind (this gives 235 FP, 10 more points would increase that to 300)
25 Endurance (optional)
20 Dexterity (optional, faster casting)
80 Intelligence (if you are going in on a casting stat, go all in)
--------------
= Level 131
(126 with Astrologer, Prisoner becomes slightly better than Astrologer if you will invest in the above AND both STR&Endurance, otherwise => Astrologer)

40 Vigor
40 Mind (this gives 235 FP, 10 more points would increase that to 300)
25 Endurance (optional)
20 Dexterity (optional, faster casting)
80 Faith (if you are going in on a casting stat, go all in)
--------------
= Level 131
(127 with Prophet, Vagabond becomes slightly better than Prophet if you will invest in the above AND both STR&Endurance, otherwise => Prophet)

40 Vigor
40 Mind (this gives 235 FP, 10 more points would increase that to 300)
25 Endurance (optional)
20 Dexterity (optional, faster casting)
45 Casting Attribute #1 (INT / FTH / ARC / STR)
45 Casting Attribute #2 (not all combinations are viable)
--------------
= Level 130
(Astrologer can reach these goals with the lowest character level if INT is one of the selected attributes, otherwise (if INT is NOT being used) Prophet becomes the best. See the "class selection" spreadsheets in the raw data for more details)

Most agree that INT or FTH builds are easier... but I personally prefer melee with some bow use and almost no casting or weapon skills, I know, I'm doing it wrong lol

So here is what I ended up with:
https://steamoss.com/sharedfiles/filedetails/?id=2799483819
https://steamoss.com/sharedfiles/filedetails/?id=2799483886

• Rune Level 175 to still be in summoning range of 150s, at least according to the Summoning Range Calculator[eldenring.wiki.fextralife.com]
  
• Never felt I needed a larger HP bar than 40 Vigor; Mitigation > Max HP
  
• Tried to limit my Endurance to 50, but two extra points were required for medium rolling
  
• 60 Strength to soft cap the Physical Defense gains and 2Handing the Cold Great Stars
  
• 20 Dexterity and 20 Intelligence for the bonus Attack Power
  
• Absolute MINIMUM Mind and Faith, but I can still cast everything with Cerulean Hidden and Faith-Knot Tears; mainly just Rot Breath on bosses
  
• 45 Arcane for the bonus status buildup with the Blood Venomous Fangs
  
• +30% AP for 20 seconds after each blood bloom (10% Head, 20% Talisman)
  
• Last talisman slot is variable; Taker's Cameo for trash, Godskin Swaddling Cloth for bosses (or w/e else I need, could even do Kindred of Rot's Exultation for another 20% AP)

This is something I had to research doing this, and it might be useful information to others. I'll hide it behind a spoiler tag tho. These steps are required because the game locks your save to your account, but it is possible to unlock it. (This fixes the "Failed to load save data" error) While you *ought* to be able to use the save online, just be warned there is no guarantee you will not receive a ban for doing so, I use donated save files offline ONLY. There is also the chance your save will become corrupted over time, MAINTAIN BACKUPS!!!

1) Download HxD hex editor. https://mh-nexus.de/en/hxd/

• ALWAYS make backups of your saves! Your save file is located at C:\Users\NAME\AppData\Roaming\EldenRing within the folder with a SteamID as its name. If you have run the steam version already there should be a folder with your ID. You will also need your donor's ID.
  
• (Optional) Turn Steam Cloud Saving off while doing this. Not sure if required.
  
• Run the game and create a character. Once past the intro, quit. (This step can be skipped if you already have a save with a character, but that save will be overwritten)
  
• Open up the two ER0000.sl2 files in the hex editor (the donor one and your own)
  
• In the donor save game right click on the page and use the "select block" option. Within the popup enter 310 in the start-offset and 28030f in the end-offset. Ensure "Hex" is selected.
  
• Right click and copy the selection.
  
• In *your* save file right click and "select block," entering the same as above in the popup.
  
• Right click on the selection and use the "Paste write" option.
  
• Now click the "Search" option in the top menu bar and select "Replace." In the popup search for the donor ID, eg. 76561197960267366. Yours will be different. Replace with your SteamID. Change Datatype to "Integer number" and select "All" from the search direction. Leave the other options as default.
  
• Once the replace is complete right click again and use the "Select block" option. Enter the same options as before eg. 310 - 28030f
  
• Click on "Analysis" in the top menu bar and select "Checksums"... within the popup select "MD-5," it's at the bottom.
  
• This will create a window at the bottom with a checksum in it. Right click on this and select "Copy."
  
• Right click and "Select block" again, this time using 300 - 30F as the start and end offsets.
  
• Right click the selection and choose "Paste write."
  
• Click "Save" up the top and be sure to delete the ER0000.sl2.bak from your SteamID folder.
  
• That should get you playing the save from the donor. (NOTE: This is only copying the save located in slot #1, if there are multiple save slots in use more work is required to copy those over, steps NOT covered here - check reddit)
  
• Here is a tool that automates all these steps:

https://github.com/BenGrn/EldenRingSaveCopier/releases/
Keep in mind all this work is done on the side of the one receiving the save file, the donor only needs to provide the file and their ID, nothing more.

If you get the "Failed to load save data" error on any save, there is the potential you could fix it just by doing the checksum steps above (that is bullet point #10 onwards, starting at "Once the replace is complete...") aka this has the potential to fix "corrupted" saves, even if you never messed with this to begin with
See the other guide links below for more info

Disclaimer: This section is not my own work, I got most of these ideas from Reddit User Danger_Fox_

If you liked this guide, you might also like my other Elden Ring guides:
https://steamoss.com/sharedfiles/filedetails/?id=2789660535
https://steamoss.com/sharedfiles/filedetails/?id=2785301831
https://steamoss.com/sharedfiles/filedetails/?id=2797241037

If you have any constructive criticism or helpful comments - I welcome such feedback.
Or if you have any questions I'll do my best to help out.
Otherwise thank you for taking a look at my guide. :)
And remember to rate and favorite this guide if you found it helpful :D

PS. Anyone using my numbers had better credit their source!!! rawr

Wow, thank you to everyone for all the awards!