What does luck do in Terraria?

Luck is a hidden stat that nudges many random rolls in your favor: item drop chances, rare critter and enemy spawns, some town NPCs' first appearance, and the Traveling Merchant's stock. Higher luck means better odds on those rolls; there is no benefit above a luck value of 1.0.

How do you increase luck in Terraria?

Drink a Luck Potion (+0.3 at full strength), farm during a Lantern Night (+0.3), place a Garden Gnome nearby (+0.2), surround yourself with biome-matched torches (+0.2), release and touch a Ladybug (+0.2, or +0.4 for a Gold Ladybug), and equip luck accessories like the Lucky Horseshoe and Lucky Coin. These stack.

What lowers luck in Terraria?

Killing a Ladybug (−0.2, or −0.4 for a Gold Ladybug) is the most common mistake. The Stinky debuff, a held Pretty Mirror, the Wilted Clover and the Raven Feather also reduce luck. Luck can drop as low as −1.1.

Mechanics

Luck, Explained

Luck is Terraria's most misunderstood stat — completely hidden, with no in-game number. It quietly tilts random rolls your way: drop chances, rare critter and enemy spawns, some NPC arrivals, and the Traveling Merchant's stock. Here's every factor with exact values, plus an estimator for your current luck.

Luck estimator

Toggle what's currently affecting you to estimate your luck. Timed effects (potions, Ladybug, torch luck) assume they're freshly active.

Estimated luck

+0.70

Raises luck

Luck Potion (full strength)+0.3
The Lucky buff gives +0.3 while over 10 minutes remain, then decays to +0.2 and +0.1. Greater/Lesser variants change only the duration.
Lantern Night+0.3
Active on the night after certain bosses, or when you release a Sky Lantern.
Garden Gnome nearby+0.2
Place a Garden Gnome within range of where you're farming.
Biome-matched torches+0.2
Up to +0.2 for surrounding yourself with torches that match the biome you're in. Mismatched torches no longer give a penalty.
Released Ladybug+0.2
Touching a released (not killed) Ladybug grants the bonus for 12 minutes.
Released Gold Ladybug+0.4
The rare Gold Ladybug grants double luck for 24 minutes.
Coins in Shimmer+0.2
Throwing coins into Shimmer grants up to +0.2 Coin Luck, which then diminishes over a few minutes.
Lucky Horseshoe+0.05
Equipped Lucky Horseshoe or any accessory upgraded from it.
Lucky Coin+0.05
Equipped Lucky Coin or an accessory that includes it.
Lucky Clover+0.03
Equipped Lucky Clover accessory.
Galaxy Pearl+0.03
Equipped Galaxy Pearl accessory.

Lowers luck

Killed a Gold Ladybug-0.4
Bad luck for 6 minutes — never kill a Gold Ladybug.
Killed a Ladybug-0.2
Bad luck for 3 minutes after killing a regular Ladybug.
Holding a Pretty Mirror-0.25
Certain held items carry a luck penalty.
Stinky debuff-0.25
The Stinky debuff lowers luck while active.
Wilted Clover-0.1
The Wilted Clover lowers luck.
Raven Feather-0.1
The Raven Feather lowers luck.

How luck actually works

Every contributing factor is summed into a single luck value, then clamped: the game never rewards more than +1.0, and it bottoms out around −1.1. So once you've stacked a potion, a Gnome and matched torches you're already near the ceiling — piling on more does nothing.

Luck only affects rolls that are coded to read it. Most ordinary item drops, rare critter and enemy spawns, and the Traveling Merchant's inventory do; boss treasure-bag contents and a few fixed drops do not. That's why luck is best treated as a gentle farming aid, not a guarantee.

The single biggest mistake is killing a Ladybug — it inflicts bad luck for minutes. Release them instead (or just avoid them) and never harm a Gold Ladybug.