Pokémon Damage Calculator Tutorial: How to Use the Showdown Calc (Step-by-Step)

The Pokémon Showdown Damage Calculator is a free web tool that lets you simulate any move from any Pokémon against any other Pokémon and see exactly how much damage it does. It’s the most important tool in competitive Pokémon outside of Showdown itself — and unlike Showdown, it has almost no friendly tutorial.

This guide fixes that. We’ll walk through every part of the calculator, what each field means, how to read the output, and how to use it for real strategic decisions.

The calculator lives at: https://calc.pokemonshowdown.com/

Key Takeaways

• The Pokémon Showdown Damage Calculator is the standard tool for predicting battle outcomes in competitive play. Free, web-based, updated every generation.
• The calculator supports every generation from Red/Blue through Scarlet/Violet and is being updated for Pokémon Champions.
• You configure both an Attacker and a Defender with their species, level, EVs, IVs, nature, item, and ability.
• The output is a damage range like “78.5 - 92.4%” — minimum and maximum percentages the move can do to the defender.
• “Guaranteed OHKO” means the minimum damage exceeds 100% of the defender’s HP — always a one-hit KO.
• The calc has four major modes: One vs One, One vs All, All vs One, and Random Battles.
• Pros use the calc to verify their EV spreads — making sure a defender survives a key threat, or that an attacker guarantees a KO.

Table of Contents

1. What Is the Damage Calculator?
2. Step 1: Select Your Generation
3. Step 2: Set Up Your Attacker
4. Step 3: Set Up Your Defender
5. Step 4: Apply Field Conditions
6. Step 5: Read the Damage Output
7. The Four Calculator Modes Explained
8. Common Use Cases
9. Calc Notation Cheat Sheet
10. Pro Tips for Using the Calc
11. Frequently Asked Questions

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What Is the Damage Calculator?

The damage calculator simulates Pokémon damage formulas exactly as they work in the actual games. Given an attacker’s stats, the move used, the defender’s stats, and any modifiers (weather, items, abilities), it outputs the damage range the move will do.

Why use it instead of just playing?

• Plan EV spreads. Test whether 252 HP / 4 Def Iron Hands actually survives a Choice Specs Iron Bundle’s Hydro Pump before grinding the EVs in-game.
• Verify KOs. Confirm that your Garchomp’s Earthquake is a guaranteed OHKO on the opposing Heatran.
• Build matchups. Test multiple Pokémon against a common threat to find the best check.
• Understand surprises. Did your opponent’s “weak” attack just KO you? Run the calc to see what spread they probably used.

The calc is hosted by Smogon and is open source on GitHub (smogon/damage-calc). It supports all generations and is updated rapidly when new mechanics drop.

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Step 1: Select Your Generation

When you open the calculator, the first dropdown at the top selects the generation you’re calculating for.

• Gen 9 — Scarlet/Violet, including Indigo Disk DLC and Tera mechanics
• Gen 8 — Sword/Shield, BDSP, Legends: Arceus
• Gen 7 — Sun/Moon, Ultra Sun/Moon, Let’s Go
• Gen 6 — X/Y, ORAS — first Mega Evolution era
• Earlier gens — Each generation’s mechanics are preserved

Why generation matters: Pokémon mechanics changed across generations. Critical hit rates, weather damage, type matchups (Steel was nerfed in Gen 6), STAB calculations, and ability behavior all vary. Always pick the right generation for what you’re calculating.

For Pokémon Champions and Reg M-A specifically, use Gen 9 as the base until the calc adds dedicated Pokémon Champions support.

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Step 2: Set Up Your Attacker

The left side of the calculator is the Attacker panel. You configure the Pokémon that will use the move.

Fields to set:

1. Pokémon Name — Type the species in the search bar. Autocomplete kicks in.
2. Level — Default is 100; change to 50 for VGC calcs.
3. Ability — Important! Some abilities boost damage (Tough Claws, Sheer Force, Adaptability). Many change the math entirely.
4. Item — Choice Band/Specs (1.5x), Life Orb (1.3x), Expert Belt, Type-boosting items, etc.
5. Nature — Adamant/Modest etc. — affects the attacking stat.
6. EVs — Stat point investment. Format: 252 in Attack (or SpA), often paired with 252 in Speed.
7. IVs — Default to 31 in attacking stat. Sometimes 0 for special edge cases.
8. Move — Pick the move from the dropdown. Type, Power, Accuracy display automatically.
9. Status — Burn halves physical damage. Toxic doesn’t affect damage but matters for residual.
10. Stat Boosts — Swords Dance (+2 Attack), Nasty Plot (+2 SpA), etc.

Common setup mistake: Forgetting to set EVs and Nature. The calc defaults to 0 EVs and Hardy nature (neutral) — which heavily understates damage for actual competitive Pokémon.

Tip: Most competitive sets have “selectable presets.” Click the gear icon next to a Pokémon’s name to see common sets — Choice Scarf, Tera Blast, Sub Slush, etc. — pre-loaded.

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Step 3: Set Up Your Defender

The right side of the calculator is the Defender panel. Same field structure as Attacker, but you’re configuring the Pokémon receiving the damage.

Fields to set:

1. Pokémon Name — The species being hit.
2. Level — Match the attacker’s level (50 for VGC, 100 for Smogon).
3. Ability — Defensive abilities like Intimidate, Multiscale, Filter, Solid Rock matter hugely.
4. Item — Assault Vest (1.5x SpDef), Eviolite (1.5x both defenses), Berry Juice, Sitrus Berry.
5. Nature — Bold/Calm/Impish — defensive natures.
6. EVs — How much is invested in HP and Def/SpDef.
7. IVs — Typically 31 in all stats for top tier.
8. Stat Boosts/Drops — Cosmic Power, Bulk Up, Intimidate from your side.
9. Tera Type — If Terastallized.

Critical note: The Tera Type field is inactive by default in Gen 9 calcs. You must explicitly toggle “Terastallize” to apply the Tera Type to the calc.

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Step 4: Apply Field Conditions

The middle panel handles battlefield conditions that affect everyone:

• Weather: Sun (boosts Fire 1.5x, Water 0.5x), Rain (vice versa), Sand (1.5x SpDef for Rock-types, damages non-Rock/Ground/Steel), Snow (1.5x Def for Ice-types).
• Terrain: Electric/Grassy/Misty/Psychic Terrain each boost specific move types and grant immunities (only affects grounded Pokémon).
• Spread Move: Toggle this on for Doubles calcs to apply the 0.75x spread multiplier.
• Reflect/Light Screen: Halves damage of corresponding category.
• Aurora Veil: Halves damage of both categories (requires Snow).
• Friend Guard: 0.75x damage from one ally with the Friend Guard ability.
• Switching In: Toggle for damage on switch-in (Stealth Rock damage etc.).

For VGC calcs, always toggle “Spread Move” when calcing a multi-target attack like Earthquake or Heat Wave. Forgetting this is the #1 calc error.

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Step 5: Read the Damage Output

The calculator’s output appears at the bottom and is the whole point of the tool. Here’s how to read it.

The Damage Range

Output looks like:

78.5 - 92.4% — guaranteed 2HKO

This means:

• Minimum damage: 78.5% of the defender’s HP
• Maximum damage: 92.4% of the defender’s HP
• Result: Always at least a 2HKO (two hits = guaranteed KO)

Why a range? Because each Pokémon move has a built-in 0.85-1.0 damage variance — every hit rolls a random multiplier in that range. The min/max represent the worst and best rolls.

KO Outcomes

• OHKO — One-Hit Knock-Out. Minimum damage > 100% of defender’s HP.
• Guaranteed OHKO — Min damage ≥ 100%, no matter the roll.
• OHKO range — Max damage ≥ 100% but min damage < 100%. Possible OHKO; not guaranteed.
• 2HKO — Average of two hits KOs.
• Guaranteed 2HKO — Even the worst rolls KO in two hits.
• 3HKO, 4HKO — More hits needed.

Crit Numbers

The calc also displays the crit damage. “X - Y% (crit)” shows what happens if the move crits (1.5x base damage in Gen 5+).

Other Indicators

• STAB: Auto-applied if the move type matches the attacker’s type.
• Tera STAB (2x): Applied if Tera Type matches the move type.
• Type Effectiveness: Shown as 0x, 0.25x, 0.5x, 1x, 2x, or 4x.

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The Four Calculator Modes Explained

The calculator has four tabs at the top:

1. One vs One

The default mode. Calculates damage from one Pokémon against one other. Use this for individual matchups.

2. One vs All

You set up an attacker; the calc shows how much damage that attacker’s best move does to every Pokémon in the game (or a subset). Useful for finding sweep targets.

3. All vs One

You set up a defender; the calc shows what every Pokémon in the game can do to your defender with their best move. Useful for checking if your defensive Pokémon has hidden weaknesses.

4. Random Battles

Specialized mode for Showdown’s Random Battles ladder, where Pokémon have pre-defined random sets. Auto-loads the random battle stat distribution.

For new players, stick to One vs One until you’re comfortable. Then learn One vs All for team-building.

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Common Use Cases

Real scenarios where the calc earns its keep.

Verifying an EV Spread

Scenario: You want Iron Hands to survive a Choice Specs Iron Bundle Hydro Pump in Sun weather (Reg I VGC).

Steps:

1. Set Attacker: Iron Bundle, 252 SpA, Modest, Choice Specs, Hydro Pump, in Sun.
2. Set Defender: Iron Hands, vary the HP/SpD EVs.
3. Toggle Spread Move (it’s not a spread move, but check anyway).
4. Adjust Iron Hands’s HP and SpD EVs until min damage stays below 100%.

You’ve now found a “survives Choice Specs Iron Bundle in Sun” defensive spread. Lock those EVs in.

Confirming a Guaranteed KO

Scenario: Your Garchomp’s Earthquake should KO opposing Garchomp.

Steps:

1. Set Attacker: Garchomp, 252 Atk, Jolly, Life Orb, Earthquake.
2. Set Defender: Garchomp (standard spread, e.g., 4 HP / 252 Atk / 252 Spe Jolly).
3. Read output. If min damage > 100%, guaranteed OHKO.

If the output says “OHKO range” (not guaranteed), you have a problem — sometimes you’ll fail to KO. Maybe you need a different item or boost.

Comparing Two Attackers

Scenario: Should you run Choice Band or Choice Scarf on Garchomp?

Steps:

1. Set Attacker: Garchomp, 252 Atk, Jolly, alternating Choice Band and Choice Scarf, Earthquake.
2. Set Defender: A common bulky threat.
3. Compare the damage ranges. The Band always does more damage but is locked into one move. The Scarf does less but outspeeds more.

The calc shows you exactly how much damage you trade for that speed.

Checking Tera Type Choices

Scenario: Should Iron Valiant be Fairy Tera or Steel Tera?

Steps:

1. Set Attacker: Iron Valiant, with each Tera Type variant.
2. Set Defender: A range of common threats.
3. Compare damage outputs.

You’ll see that Fairy Tera turns Moonblast into a wallbreaker, while Steel Tera makes Iron Valiant nearly invulnerable to common Dragon threats.

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Calc Notation Cheat Sheet

Quick reference for what the symbols and abbreviations mean.

Notation	Meaning
252+ Atk	252 EVs in Attack with a positive nature for Attack
252+ SpA	252 EVs in Special Attack with a positive nature
0- Atk	0 EVs in Attack with a negative nature (minimum Atk)
4 HP / 252 SpA / 252 Spe	EV spread: 4 HP, 252 SpA, 252 Speed
Modest	Nature that boosts SpA, lowers Atk
Choice Specs	Item that boosts SpA by 50%, locks move
Tera Type: Fairy	The Tera Type assigned
(crit)	The move was a critical hit
2HKO	Two-Hit KO
OHKO range	Possible OHKO, not guaranteed
Sub	Substitute is active
Booster Energy	Activated Booster Energy boost (paradox Pokémon)

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Pro Tips for Using the Calc

1. Always check both rolls. Look at min AND max. “OHKO range” doesn’t mean OHKO — it means “could be an OHKO with the right roll.” Plan around the worst case, not the best.

2. Account for crits. Crits are 1/24 base chance. In a long match, expect at least one crit on average. If a defensive Pokémon can be 2HKO’d on a crit, that’s relevant.

3. Test the matchup both ways. Don’t just calc what your attacker does to the opponent. Calc what the opponent does to your attacker. Speed control is everything in Doubles.

4. Use selectable sets for opponents. You won’t always know the exact spread of an opposing Pokémon. The calc has “popular sets” for most viable competitive Pokémon — use those as a starting estimate.

5. Save calc URLs. The damage calc encodes the entire setup into the URL. You can copy/paste a URL to share a specific calc with a teammate. Useful for discussing teams.

6. Calc multiple opponents at once. Use One vs All to see what your attacker does to the whole metagame. Adjust EVs based on which threats you must KO.

7. Don’t forget the per-turn dilution. The calc doesn’t know that opposing Pokémon might Protect or switch. Calcs are theoretical maximums — actual matches involve prediction.

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Frequently Asked Questions

What is the Pokémon damage calculator? A free web-based tool at calc.pokemonshowdown.com that simulates Pokémon battle damage formulas to predict how much damage moves will do.

Is the calculator accurate? Yes. The Showdown calc uses the actual damage formulas from each Pokémon generation and is open source on GitHub. It’s the same math the games use.

Does the calc include Tera Types? Yes, for Gen 9 calcs. Tera Type must be toggled “on” for the Tera STAB and defensive type swap to apply.

Can I use the calc for VGC? Yes. Set both Pokémon to Level 50 and toggle “Spread Move” for moves that hit multiple targets.

How do I read damage like “85.5 - 100.5%”? This means the move deals between 85.5% and 100.5% of the defender’s HP. Since max exceeds 100%, it’s an “OHKO range” — sometimes KOs, sometimes doesn’t. Min < 100% means it’s not guaranteed.

What’s a “guaranteed 2HKO”? Two hits are guaranteed to KO the defender, even at minimum damage rolls. The damage range’s lower bound × 2 ≥ 100% of defender HP.

Should I calc with or without crits? Calc without crits for the typical case. Check crit calcs to see if your defensive Pokémon can survive a critical hit — useful for ensuring safe switches.

Does the calc support older generations? Yes. Every generation from Gen 1 through Gen 9 is supported. Each preserves that generation’s specific mechanics (Special split, type changes, etc.).

Why doesn’t my damage match the calc? Most often: forgot to apply Spread Move multiplier (Doubles), wrong generation selected, wrong EV/Nature applied, missing an ability or item, or weather/terrain unchecked.

Can I save my calculations? The calc encodes setups in the URL. Copy the URL to bookmark or share. There’s also a “history” feature in newer versions that retains your recent calcs.

Is there a mobile version? The web calc works on mobile browsers, though it’s cramped. Some unofficial mobile apps mirror the calc’s functionality with better UX.

How do I calc Booster Energy boosts? Click the ability dropdown and select “Quark Drive” (Iron-line Paradox) or “Protosynthesis” (ancient Paradox), then toggle the “Booster Energy Active” checkbox.

Does the calc support Pokémon Champions? As of May 2026, the calc supports Gen 9 mechanics (including Mega Evolution from Champions/Z-A). Pokémon Champions-specific updates are rolled in continuously as the format settles.

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Want to use the calc effectively? Pair it with our Competitive Pokémon Lingo Cheat Sheet and VGC 2026 Regulation Guide.

Need a team to test in the calc? Generate a Showdown-compatible export with the Pokedexgenerator.com team builder.