The damage meter (also called the damage gauge, stamina meter, HP meter, HUD, player display, or health meter, among other names) is a UI element displayed during gameplay that presents basic information and status for each player at a glance. True to its name, the meter most prominently keeps track of a player's damage, though other statistics are generally shown here as well.
The damage meter displays the damage percentage a player has accumulated (shown in decimals in Ultimate), as well as their score or number of stocks remaining where appropriate. These are superimposed over the character's series symbol. Starting with Brawl, the background of the meter also contains the character's portrait and a name bar; Ultimate would see a further redesign of these elements with an angled portrait and darkened name bar backing. The number of stock remaining is represented by the number of icons (nondescript pips in Brawl, the character's head in other games), while score is displayed with a simple integer value. A stock higher than five (six in the original game) is represented by one icon with a multiplier value next to it; having fifteen stocks, for instance, would show "× 15". In Brawl onward, the damage percentage itself can be disabled in More Rules, although all other elements will still be displayed. Scores in time battles can also be toggled on and off starting with Melee, although they are off by default; while a default feature in later games, Melee itself requires players to unlock this toggle by accumulating 5,000 KOs on their save file.
Generally, damage meters are fairly compact and overlaid atop the gameplay at the bottom of the screen, although Smash 4 also contains a vertical, full-screen variant that's instead shown on the system's secondary touchscreen; the 3DS version uses this variant almost exclusively (and additionally allows players to choose whether damage is displayed above or below the portrait), whereas the Wii U version merely has it as an optional feature. While normally opaque, on-screen damage meters from Brawl onward become translucent if a character goes behind them. The damage percentage itself changes color when more damage is accumulated. At low percentages, the value is white, but gradually turns maroon as it increases, reaching its darkest at around 300% (200% in Smash 4); starting with Brawl, the value will also shift through red first, and Smash 4 further adds a yellow hue before that. In addition, the Wii U version of Smash 4 displays the value with a metallic gradient. Starting in Brawl, the damage meter of a character who is KO'd appears to more or less "explode", and starting in Smash 4, the on-screen damage meter of whoever made the KO is briefly engulfed in flames.
In free-for-alls, the background of a player's damage meter is colored depending on their controller port: for human players, Player 1 is red, Player 2 is blue, Player 3 is yellow, and Player 4 is green, while CPUs are gray. In team battles, the coloring is instead based on players' teams, with CPUs using a paler tone than human players. As of Smash 4, more colors have been added for Amiibo support and 8-Player Smash: Player 5 is orange, Player 6 is cyan, Player 7 is purple, Player 8 is slate, and Amiibo FPs are rainbow-colored. Certain bosses in Smash 4 also have unique meter colors. As of Ultimate, Player 8's color has been changed to purple, while Player 7 is now pink, effectively replacing the slate color. If 5 or more players are playing, the damage meters will be smaller than playing with 2-4 players.
Starting with Brawl, a player's current damage percentage will also occasionally display where their player marker usually is. This is generally only while at higher percentages in Brawl, but is more common in later games.
The meter will sometimes show additional information during certain situations. This can be in the form of additional gauges and icons, or through alteration of existing elements. These include:
Main article: Stamina Mode
In certain scenarios such as Stamina Mode or fights with bosses, a character's health is measured in HP rather than damage. In this case, the meter remains largely the same, though the value is affixed with an "HP" symbol rather than a percentage sign, counts down upon taking damage rather than up, and, in the Wii U version, shift through other colors, such as starting silver then turning bronze. These can appear alongside normal damage meters, such as the Master Hand fight where the boss's health is an HP value while the player retains the usual damage mechanic.
A different type of HP meter is used in the Subspace Emissary for all non-Smasher enemies, as well as in Brawl's Boss Battles mode. These meters are displayed as a horizontal red bar similar to a more traditional health bar rather than an exact numerical value, and appear above their owners for minor enemies and at the top of the screen for bosses. They are generally more difficult to strategize around, as one does not know exactly how much health an enemy has, especially since this kind of meter seems to be somewhat non-linear. Ultimate will go on to use the same kind of meter for all bosses in all modes, including Classic Mode.
Unique among all enemies is Master Core in Super Smash Bros. 4 - its meter at the bottom of the screen is obscured by a Swarm cloud in the 3DS version and disappears entirely in the Wii U version, intentionally making it impossible to know its maximum and current HP. In the 3DS version, once Master Core is defeated and reaches its final, vulnerable form, the Swarm obscuring the meter clears to reveal the boss's identity and a standard damage percentage starting at 0%, as it must be KO'd normally to finally end the match. The meter does not reappear in the Wii U version, but the final goal remains the same.