A Critical hit or Crit is 300% normal damage for melee weapons, and 200% for ranged weapons. Your crit chance increases slightly with the amount of damage you dealt in the past 20 seconds. Also, critical projectiles have a team colored trail behind them, but some are cosmetic trails such as the trail of a crit-boosted Mad Milk. Fire also has additional particals that differ depending on which team the player is on. For ranged weapons, (non-melee) the regular crit chance is 2%. This increases by 2.5% evey 200 damage you deal, up to a max of 12% total chance of critical hits. They check for critical hits once every second, and if a random crit happens, the next 2 seconds for that weapon only will be critical hits wether they stop firing and resume or switch their weapons. The weapon will not appear crit-boosted when this happens, as it is a random crit. Non-rapid fire weapons, such as the Shotgun or the Rocket Launcher roll for critical hits every shot, if the shot is lucky, the player will fire a critical flurry of pellets or critical rocket. Rapid fire weapons check for critical hits once a second, such as a Pistol or the Minigun. If a critical hit chance is sucsessful, the next 2 seconds are critical hit. This will not carry over to the next weapon if they switch, though it wil continue if they switch back in time. Melee weapons have a much higher crit chance, their lowest crit chance is higher than the max crit chance for ranged weapons to encourage their usage at close range. They start off with a crit chance of 15%, up to a max of 65% with 12.5% being added every 200 damage dealt. A critical melee attack almost always has a special animations, such as the Heavy's Fists doing a up-punch and a Shovel doing a back-handed swing. Ranged weapons do not have a unique critical firing animation. Not all weapons or attacks can do critical hits, such as kill Taunts and a example of a non-critting-damage-dealing weapon under the circumstances is the Chargin' Targe. The Cow Mangler 5000 also cannot do critical hits in any means, but can mini-crit. In the kill feed, players killed by a critical hit will have a red glow around the weapon picture. Common examples of this are Headshots and Backstabs.
A Mini-Crit is generally a watered down Crit, as it does 35% extra damage. It cannot be obatined by chance, but rather by specific item effects, such as Jarate and being marked for death or being hit with a shot from a Sydney Sleeper . The only weapon that cannot obtain mini-crits is the Sniper's Bushwacka as all mini-crits turn into critical hits. Other than that, all weapons can deal mini-crits providing that they deal direct damage, like the Splendid Screen. Unlike critical hits, Taunts can mini-crit, and if he taunt does the usual 500 damage, it will do 675. There are exceptions, such as the Pyro's taunt Execution, which normally deals 400 damage. Like critical hits, in the kill feed players killed by a mini-crit will have a red glow around the weapon picture, such as a cow mangler 5000's charged shot or a Airblasted projectile that killed a enemy/friendly player.