A single pea fired by a Peashooter in the original Plants vs. Zombies inflicts 20 damage. That makes the Peashooter the game’s basic ranged attacker and establishes the damage value used by several related pea-firing plants.
The Peashooter is one of the first plants introduced and costs 100 sun to place. It fires repeatedly down its lane, giving the player a reliable way to handle ordinary zombies. Since a basic zombie has about 200 hit points, approximately ten unmodified peas are needed to defeat one, assuming every shot connects and no other damage is involved.
The 20-damage figure applies to a normal pea, not every projectile in the pea family. Repeater fires two peas per attack, while Threepeater attacks multiple lanes, so their total output is higher even when each individual pea uses the same basic damage value. Snow Pea also deals normal projectile damage while adding a slowing effect, and Torchwood can modify peas into stronger fire peas.