Resident Evil 7 has an internal difficulty adjustment mechanic that tries to counter the player's performance by reducing or increasing the damage output based on a ranking system. Those who played the next RE game on this game engine, Resident Evil 2 (2019) probably already know about it.

The system relies on a rank meter that ranges from 0 to 9999, divided into three blocks based on the selected difficulty:

• Easy mode: Starts at 1200. Min: 0, max: 2999.
  
• Normal mode: Starts at 4800. Min: 3000, max: 6999.
  
• Madhouse mode: Starts at 8500. Min: 8000, max: 9999.

Dealing damage in any form increases the meter, getting hurt or dying decreases it. The exact amounts depend on the weapon or the enemy attack type, not the damage dealt or received.

To give some perspective on the accumulation rate: assuming you never get hit during the guesthouse section in the two Mia fights, you will go from 4800 to above 6500 by the time you reach the main house. A good player can expect to stay at the highest rank of the given difficulty right from the garage fight.

The game categorises the score into ten ranks, ranging from 0 to 9, where each has a universal damage multiplier:

Note: Rank 7 technically does not exist, but even if you achieve it using cheats, it just uses Rank 6 values.

Similarly to player damage, the rank also affects enemy damage, but not their health pool. The same monster will always have the same HP on all difficulties (except for the two fat molded at the end of the game).

There are three coins in the game that also affect the damage dealt by the player.

• Assault coin: It is only available on madhouse difficulty, from a birdcage in the main house lobby (or the mining shack after the ship). It costs 8 antique coins.
  The Assault coin gives you a +15% damage bonus.
  
• Attack coin: It was available only as a DLC purchase. Once you bought it, it was put in the item box and returned there every time you discard it from the inventory.
  The Attack coin gives you a +6% damage bonus.
  Note: The coins DLCs have been removed from the store and cannot be purchased by new buyers. If you bought them before the de-listing, you can still use them in the game.
  
• Universal coin: It was available only as a DLC purchase. Once you bought it, it was put in the item box and returned there every time you discard it from the inventory.
  The Universal coin gives you a +2% damage bonus.
  Note: The coins DLCs have been removed from the store and cannot be purchased by new buyers. If you bought them before the de-listing, you can still use them in the game.

The bonuses are additive, so having all three coins in your inventory gives you a total +23% damage bonus.

Weapon damage is not entirely universal. While all have a base damage value that can cover many enemy types, different enemies and bosses have their unique weaknesses or vulnerabilities against specific weapon categories. The following list is meant to be here as a reference to have at least some numerical data as a baseline.

All damage values represent the Rank 4 (×1.00) stats. If you need a more detailed chart for each rank, then you can view the Excel file from this address:
https://1drv.ms/x/s!AiFe2XfiCX8WiPIAliwa8ccM7YHDpQ
(It looks a lot better once you download it, some of the formatting is not displayed in online format. No, I do not use Google Docs, I do not like it.)

The first value is the primary attack, the second one is the secondary.
*If you use cheats to get the survival knife before the ship, it acts as a pocket knife with the same damage.
**The secondary attack is continuous as long as you keep holding down both the aim and attack button. The frequency of the damage is dependant on your current framerate.
***The crowbar is only accessible if you decided to cure Zoe and enter the final Mia fight as a consequence. It behaves the same as the axe from the beginning.
****While the chainsaw is only accessible during the only fight in the game that does not depend on difficulty rank, if you use cheats to transport it outside the arena, it behaves like a weird cousin of the circular saw (and it scales on enemies who are not Jack).

The first value is with normal ammo, and the second value is with enhanced ammo (triple damage)
*The Albert-01 at the final boss fight is a scripted weapon. You can cheat it into the main campaign, but it acts like a basic pistol that cannot use enhanced ammo and it is half as strong as the replica. It can act as a flashlight though.


*The grenade launcher is impossible to measure properly (the same goes for the RE2Re one). First, it deals massive impact damage, but that already carries a roughly 50% variance, even if you shoot the same enemy on the same difficulty, at the same distance, and the same spot. Then, it starts a damage over time (DoT) effect, where each tick deals an average amount of damage, but the amount of ticks a DoT stack lasts is also random. Some enemy types are flat-out immune to certain grenades; some can burn for any given length between 15 to 80 damage ticks.
**The burner (again, like the chemical flamethrower of RE2Re) has two-stage damage. Every puff of flame that connects can do some small impact damage, which depends on your distance to the enemy; the displayed 20 requires you to stand right in their face. If you hold the trigger down and set the target aflame, they also suffer from a DoT, similarly to the grenade launcher. Every enemy has a default length for a DoT stack, but continuous damage can lengthen it indefinitely.

This section is by courtesy of cheezeit.


From what I've seen, the game uses two types of damage.

Type A (normal) is the regular kind. Empty an enemy's health, and they die. This can be adjusted by the Attack Coin, Assault Coin, Universal Coin, Toughness 2, and Firepower 1/Firepower 2 items. This damage seems to be adjusted by the dynamic difficulty multiplier.

Type B (stun) is in regard to triggering special animations like knockback; it also controls limb damage. It can be adjusted by the Instinct Coin, Universal Coin, Defense 2, and Impact 1/Impact 2 items. I used to refer to this as Instinct Damage but I've come to call it Impact Damage because the JBP item makes it actually useful. The dynamic difficulty multiplier doesn't seem to touch this type of damage, meaning, to pop a given molded's head takes the same amount of shots at Rank 6 as it does at Rank 3. There are no variations in it, like in Resident Evil 2 (2019) (where, for example, you can focus your shots or get random critical hits).

• Roaming Jack's knockout is dictated by Type B damage which is why those coins won't help to knock him out.
  
• Chainsaw Jack changes back and forth between Type A and B. When walking around, he takes Type B just like his roaming form (this is why his normal HP does not deplete at all). When he is down, he takes Type A from his normal 4500 HP health pool.
  The body bags hanging around have 1000 HP each and pop when they are emptied by Jack's attacks.
  
• Weirdly enough, it seems the devs put multiple types of Insect Hives in the game. Some only spawn insects under certain conditions and the different types have different health. The two with 2800 HP on the bridge and in the middle of the fireplace room actually become much more aggressive the instant you combine both parts of the flamethrower. Very strange detail.
  
• The "knife exploit" of RE2 (2019) is also present in this game. However, the delay is a lot higher… around a full second.
  If you swing your knife just right, you can sometimes hit an enemy twice. Similarly to RE2 (2019), the higher the framerate, the more likely for this to happen. In relation to this observation, Carcinogen stated in an older speedrun that this effect applies to enemies with melee damage as well. RE2 (2019) prevents the player from getting double-hit by applying invincibility frames (you are invulnerable for a short time after getting hit), but RE7 lacks this mechanic.
  
• The Albert-01R and the shotguns seem to do more damage to regular molded after the greenhouse fight. No idea why.
  
• Joe's spirit blade heals him by 10% with a light swing and 15% with a heavy. I forgot if it would heal more if you happen to land a mult-hit.
  
• The different AMGs are a bit strange with how they affect normal molded. The AMG-Dual is of note compared to the AMG-78a because it's RLRL combo to a molded does a good bit less damage (about -40%). However, its Type B damage is much greater (×3). This means that molded heads will pop easier with it but it is at a disadvantage with body hits. Honestly, I dunno offhand if a molded can survive an AMG-78a head combo anyhow. Also, I never go around to testing how bosses react to different AMGs.

A couple links of my notes if they can be of any use (Apologizes if there are mistakes):
https://gamefaqs.gamespot.com/boards/191629-resident-evil-7-biohazard/76931349
https://pastebin.com/YDBpybnb

To keep this guide short, this chapter only lists the weaknesses and resistances for each enemy. The values relate to the weapon damage chart above.

If you want the full table with all (feasible) weapon damage per each enemy type, you can check the Excel file here:
https://1drv.ms/x/s!AiFe2XfiCX8WiPIAliwa8ccM7YHDpQ

HP values:
Before the boat: 3000
Mia (flashback): 1500
Mia (present): 1200
Swamp: 1200
Mine, first half: 3000
Mine, gauntlet: 1500

Weak spot: head (+200%)
Strong spot: limbs (−40%)
Bladed molded have triple HP on their limbs and head.

Shotguns: +70%, a full headshot is instakill.
Magnum: shoots off any limb in one shot, including the head.
Albert-01R: According to user Krombopulos Michael, a headshot with enhanced ammo on the upper part of the head is enough to kill most molded but the strongest bladed ones.

HP: 900

Weak spot: head (+50%)

Shotguns: +25%, a full headshot is instakill.
P19: +25%
Grenade launcher: instakill within the blast radius (both grenade types)
Magnum: a headshot is instakill.
Albert-01R: According to user Krombopulos Michael, a headshot with enhanced ammo on the upper part of the head is enough to kill all crawler molded.

HP values:
Barn fight: 10,000
Barn fight (large, madhouse): 15,000
Ship 2F (madhouse): 1500
Ship 3F: 4500
Ship S2: 3000
End of mine gauntlet (madhouse): 8000
Final two before the long ladder (easy/normal): 3500, 9000
Final two before the long ladder (madhouse): 14,000, 24,000

Strong spot: head (−50%); however, it has a much lower sub-hitpoint pool, so you still should aim at it.

Magnum: can do higher damage to the head, most of them fall in 2-4 headshots.
P19: +100%
Grenade launcher (neuro): around +10% damage (inconclusive)

HP: 150

Melee weapons: +200%
G17, M19, and shotguns: +100%
Grenade launcher: −50–80%
Burner (DoT only): −90%, but the DoT is a lot faster

HP: 2400

Melee: +200%
Grenade launcher: instakill within the blast radius (both grenade types)
Burner (DoT only): −60%, but the DoT is a lot faster

HP: 800

Melee, pistols, and magnum: −50%
Shotguns: −20%
Grenade launcher: Only splash damage can hurt the swarm, otherwise the first grenade flies through, a second one disperses (despawns) it.
Burner: +150 contact, −60% DoT – however, it is the best weapon against it.

I am going in order of appearance.

HP: 700

Nothing special here.

HP: 2000

Weak spot: head (+100%)

HP: 10,000

Weak spot: head (+100%)

Pocket knife (swing only) and circular saw (continuous damage only): +100% while he is in the car

HP: 4500

He is invulnerable until he exposes his weak spot, but for that, you need to dish out damage.
This is the only fight in the entire game that completely disregards difficulty; you do the same amount of damage on every rank.

Melee weapons can damage him multiple times while he is vulnerable. Shooting him will instantly break the animation after the first shot, and he becomes invulnerable again. The developers really want you to use the chainsaw (or circular saw).

HP: 1500

Before the crow door fight, every weapon: −50%
Grenade launcher: −40–50% (flame), −75% (neuro) — commutative with the −50% while she is patrolling.
Burner: +150% (contact), −50% (DoT, crow door fight)/−100% (while she is patrolling)

HP: 15,000

Weak spot: head (+10%)
Strong spot: egg sac (−20%)
(As a side note: the latter one is what seemingly everyone got wrong.)

Grenade launcher: −60–80% (flame), −70–90% (neuro)
Burner (DoT only): −83%

HP: 30,000 (body), 500–5000 (eyes)

Strong spot: arms (−20%)

You cannot deplete the health of the body; it stays at 1 HP. You must shoot the eyes.
The grenade launcher's and burner's applied DoT effects can destroy random eyes; however…

Grenade launcher: −50–60% (flame), −60–75% (neuro)
Burner (DoT only): −66%, and it also takes ages for him to catch fire.

HP: 700

Only happens if you chose Zoe. Otherwise, the fight is identical to the first one with her.

HP: 6000
Only applies to the first phase. The next two phases are scripted.

Melee: +320%, but make sure you are not caught in her instakill attack when you get close. Furthermore, the more she moves forward, the higher the damage bonus gets. This bonus only applies to melee weapons.
Magnum: +25%
Grenade launcher: ??? (testing showed full damage in the range of 100–2400/shot)
Burner: +100% (contact), −100% (DoT; cannot catch fire)

The DLC uses its own unique difficulty system. While it counts difficulty score, your damage is not based on that. So far, it seems that all three difficulties have their set damage chart, and you are moving between the difficulty levels, not ranks: playing well on easy will get you to normal, playing well on normal gets you professional damage levels (not enemy composition).
Professional is the only unique one, playing badly there will give you +20/40% damage bonuses for a while—seems to reset whenever you reach the next checkpoint.

The coins work the same way here as in the campaign.

The three numbers represent the base damage of each difficulty, as those were the ones I could reliably test. Except for the grenades, which have randomised elements: frag grenade damage is based on proximity, neuro and incendiary have damage over time (DoT) damage that can be mitigated by certain enemy animations.

Molded (normal and bladed)
HP values:
Almost all enemies: 2200 HP
Mining shield gauntlet: 3500 HP
Bladed one in lab observation room: 5000 HP

Crawler molded
HP: 900
(Except on the infected tunnels on professional, those have 400 HP)

Fat molded
HP values:
Shield gauntlet: 20,000 and 25,000 HP
Infected tunnels (professional): 2500 HP
Laboratory (professional): 6000 HP
*I have no idea why it does so much more damage on normal.

Headless molded
HP: 1000

Fumer
HP: 10,000
*It does not have an actual regeneration, you can kill it with a knife.

Mama Mold
HP: 50,000
*It does 1000 damage on all difficulties when you first meet it, but it is immortal at that encounter and stays at 1 HP.

Lucas
HP: 28,000
If you do not shoot at the heart, then he has 75/85% damage reduction, but not against grenades.

End of Zoe does not care about the difficulty score, nor uses any ranks. Your damage is based only on the chosen difficulty level and it is always consistent while using the same weapon on the same enemy type.
Normal, as usual, has the base ×1.0 multiplier. Easy has a ×1.5 multiplier, the Joe Must Die difficulty has a ×0.7 multiplier. Most weapons follow this pattern, the exceptions are noted below.

On top of the two DLC coins that act similarly as in the campaign, this scenario also lets you collect two effigy types: boxer and champion effigies. Boxer effigies give 1%, champion ones give 5% universal damage boost (so, not just for the fists).
As usual, all of these are additive, so having 10 boxer effigies, 1 champion effigy, and the attack coin will give you 10×1+1×5+1×6=21% universal damage boost.

The damage values are for Normal difficulty.
The story-mandated AMG-78 does half damage with normal punches but retains the full value on charged ones.
On Joe Must Die difficulty, the AMG-78a does 105/350 damage. The plot-mandated AMG-78 does 210/1400, retaining the difficulty's standard damage penalty.
The dual AMG-78a does not have any damage penalty, both gauntlets do the same damage.
The throwing spear damage is unique for all enemy types. Similarly to a shotgun, a headshot with it counts as critical damage and kills all normal and crawler molded, regardless of their HP.
Unlike its main campaign counterpart, the M21 shotgun fires 8 pellets. The value is for a full blast.

Bare hands
You can do two combos with your bare fists: left-right-right for fast, right-left-right-left for strong.
The fast combo ends with Joe punching rapidly. The number here represents the damage of one hit (since it is rare to have an enemy get hit by all).
The last two punches of a strong combo (right uppercut and left jab) are stronger than the first two. The number here is only for the final hit, the third punch is half as strong as that.

Base punch (left or right): 100
Fast punch: 60/punch
Strong punch: 300

Unless stated otherwise, the damage from the Weapons chart applies.

Molded (normal)
HP: 2000

Weak point: head (+100%)

Throwing spear (E/N/JMD): 3000/1200/1400 (I have no idea why Normal is the lowest.)
Shotgun: +70%, headshot is fatal.
Stake bomb does 6000 damage instead of 3000 on Easy.

Crawler molded
HP: 900

Throwing spear (base): 500
Shotgun: +25%, headshot is fatal
Stake bomb: since its head is always on the ground, almost all explosions are fatal

Double-bladed molded
HP: 3000

Throwing spear (E/N/JMD): 4500/1000/910
Shotgun: +100%, but its head does not have any vulnerability or damage bonus
Strong punch does 1200 damage for some reason, but only on Normal.

Fat molded
HP values:
Cemetery (easy/normal): 6000
At the main entrance of the old house: 2000

Joe Must Die exclusives:
Starting area: 2100
Ship: 5000
Gator area (standing on the pier): 4000
Gator area (extreme challenge): 6000
Cemetery: 4200 (both)
After getting the AMG-78: 2000
Old house, after gallery room: 2800

Throwing spear (E/N/JMD): 900/400/280 +100% head damage
Shotgun: −25%, −50% head damage

Swamp gator
HP: 800
The two gators exclusive to the JMD difficulty have 700 HP.

Throwing spear (base): 1000
AMG-78a (easy/normal): −25%
Spirit and throwing knives do +5% on JMD instead of −30%

Swamp Man 1 (corridor)
HP: 1000

Throwing spear (base): 700
AMG-78a (easy/normal): −75%
Spirit knife: +100%

Swamp Man 2 (ship)
HP: 8000

Throwing spear (base): 700
AMG-78a: −87.5% (easy/normal), −50% (JMD)
Spirit knife: +100%
Shotgun: −50% headshots (easy/normal)
The special follow-up attack exclusive to this fight does 2500 base damage.

Swamp Man 3 (house)
HP values:
Easy: 16,000
Normal: 14,500
Joe Must Die: 11,000

Throwing spear (base): 700
AMG-78, punch (E/N/JMD): 225/300/105 (−50% head damage on easy/normal)
AMG-78, charged (E/N/JMD): 1500/500/350 (−50% head damage on easy/normal)
AMG-78a: −87.5% (easy/normal), −50% (JMD)
Spirit knife: +100%