Charisma

Charisma is one of the seven primary statistics in the SPECIAL character system.

Fallout, Fallout 2 and Fallout Tactics
In Fallout 2, Charisma also determines the number of base companion slots the player character is given. This number is equal to their Charisma score divided by two, rounded down. As an example, with a Charisma at five, two can be recruited. Please note that one companion can still be recruited (in a few cases) even with the lowest Charisma score.

Predesigned Primary Charisma-based Characters (PPCC) of Fallout are Albert, and in Fallout 2's case, Chitsa.

In Fallout Tactics, Charisma is, at best, a secondary trait. Due to the nature of the game (i.e. almost exclusively combat-based) it is feasible to complete the game easily with 1 or 2 Charisma with no penalty. The only role is that when the Warrior starts with Charisma of 10, their rank is Senior Initiate, rather than Initiate. It is involved with the Barter skill and promotions, and is required for the Leader and Divine Favor perks. A low Charisma, on the other hand, gives access to the Loner perk.

Ways to increase Charisma in Fallout

 * Find the Singer random encounter. Speaking with Patrick the Celt and passing a Speech check will increase Charisma by one.
 * Pop some Mentats for a temporary +1 Charisma.

Ways to increase Charisma in Fallout 2

 * Install the blue memory module into ACE, then request the following surgery. Charisma will be increased by one.
 * Take the Gain Charisma perk for another point.
 * Having the mirrored shades, obtained from Mason (Salvatore's Bar, must be looted) or one of the graves in Golgotha, active in one of the item slots increases Charisma by one point.
 * Pop some Mentats for a temporary +1 Charisma.

Fallout 3
Modifies: Speech and Barter skills, NPC Disposition

Charisma increases the disposition of all NPCs, which makes Speech checks easier. Disposition is also affected somewhat by Karma (most NPCs like good characters more), quests (doing a quest in a way an NPC likes can dramatically boost disposition), and dialog options (being a jerk in conversations can lower disposition a little). Charisma also affects the Barter and Speech skills. Characters who use Speech will want at least a decent Charisma, but adding points to the skill is almost always better than adding points to the score. Characters who do not use the Speech skill have little use for this SPECIAL score.

There are also general Charisma checks in dialogue with some characters, in addition to Speech checks. Avoid wearing things like Enclave Power Helmets, as they deduct 1 point of Charisma while equipped.

Ways to increase Charisma

 * Permanent
 * Bobblehead - Charisma (+1)
 * Intense Training perk (+1)
 * No Weaknesses perk (will raise base to 5, if below 5)
 * Almost Perfect perk (will raise base to 9, if below 9)
 * Temporary
 * Alcohol (effects do not stack)
 * Beer, scotch, vodka, whiskey, wine (+1)
 * Moonshine (+2)
 * Armor and clothing
 * Eulogy Jones' suit, regulator duster, sexy sleepwear, sheriff's duster, Tenpenny's suit, Vance's longcoat outfit (+1)
 * Eulogy Jones' hat, T-51b power armor helmet, Three Dog's headwear (+1)
 * Winterized T-51b power helmet (+1)
 * Ashur's power armor, Leather Rebel (+1)
 * All-nighter nightwear (+1)
 * Grifter's Fit (+1)
 * General Chase's overcoat, Paulson's outfit (+1)
 * Chems
 * Ant queen pheromones (+3)
 * Grape Mentats (+5)

Fallout: New Vegas
Charisma in New Vegas modifies Barter, Speech and Companion Nerve. Companion Nerve gives each companion in the party +5% to their damage and armor, up to a maximum of +50% at 10 Charisma.

Regardless of Barter or Speech level, some interactions will not be available with a too low Charisma (Ex. Corporal Betsy). These ultimately do not have any significant effect on game play, nor do they provide any special bonuses.

Ways to increase Charisma

 * Permanent
 * Charisma Implant available at the New Vegas medical clinic (+1)
 * Intense Training perk (+1)
 * Completing the quest The Apocalypse or The End will allow raising any one primary statistic by 1.
 * Temporary
 * Alcohol (effects do not stack)
 * Absinthe, beer, Jake Juice, scotch, vodka, whiskey, wine (+1 - +3 depending on Survival skill)
 * Irradiated beer, irradiated scotch, irradiated whiskey (+1 - +3 depending on Survival skill)
 * Large wasteland tequila, wasteland tequila (+1 - +3 depending on Survival skill)
 * Moonshine (+2)
 * Armor and clothing
 * Bounty hunter duster, regulator duster, sexy sleepwear, sheriff's duster, sleepwear (+1)
 * T-51b power helmet, Eulogy Jones' hat (+1)
 * General Oliver's uniform (+2)
 * Vera's outfit (+1)
 * Dr. Mobius' scrubs (+1)
 * Armor of the 87th Tribe, Ulysses' duster, elite riot gear (+1)
 * Chems
 * Mentats (+1)
 * Ant queen pheromones (+3)
 * Party Time Mentats (+5)
 * Traits
 * Claustrophobia (+1 while outdoors, but -1 indoors)
 * Early Bird (+2 between 6am and 12pm, but -1 between 6pm and 6am)
 * Meat of Champions perk (+1 for 60 seconds after eating a corpse.)
 * "Mood Light" (+2 for 12 hours or until the player uses the "Smart Lights")

Fallout 4
Charisma affects the maximum amount of settlers allowed at a settlement:
 * $$Max Population = 10 + Charisma$$

It also affects item buy/sell values; the value of an item for buying or selling is its innate value multiplied by either the buying price modifier or the selling price modifier:
 * $$Buying Price Modifier = -0.15 \times Charisma + 3.50$$
 * $$Selling Price Modifier = 1 / Buying Price Modifier$$

Other price factors are below.

Friend Discount is when you get better prices from a vendor for completing a quest. I got this from Connie Abernathy for returning a locket to her husband. Other vendors may have the same or other discounts.

Multiply the modifier from charisma and all applicable modifiers above to get the (near) final modifier. If you get a final buying modifier that is less than 1.2, the game will use 1.2. If you get a final selling modifier that is greater than 0.8, the game will use 0.8.

Note: The minimum purchase price is 120% of the item's value, and the maximum selling price is 80% of the item's value. It appears like this applies even after you get a discount from a Vendor.

To get the best prices: Without any of the other factors above, you need 16 CHA for buying, 15 CHA for selling. With Cap Collector 1 Perk, you need 15 CHA for both buying and selling With Cap Collector 2 Perk, you need 13 CHA for both buying and selling. With Cap Collector 2 Perk, and the Barter Bobblehead, you need 12 CHA for selling. With Cap Collector 2 Perk, the Barter Bobblehead, and all 8 Jerky Vendor issues, you need 8 CHA for buying.