What is STAB in Pokemon Yellow?

Same Type Attack Bonus. If the move type matches one of the user's types, damage gains an extra floor(damage / 2) after the +2 step—effectively 1.5× in integer math.

Are Physical and Special split by move in Yellow?

No. Category is determined by type. Physical types use Attack vs Defense. Special types use the single Special stat on both sides.

Why is the damage range so wide?

After bonuses, Gen 1 multiplies by a random integer 217–255 inclusive, then divides by 255. That produces the classic min–max roll window.

Pokemon Yellow Damage Calculator - Gen 1 Battle Tool

Q: How does damage work in Pokemon Yellow?

Yellow uses the Generation I integer damage formula: build a base from level, power, and Attack/Defense (or Special), add STAB and type effectiveness, then multiply by a random roll from 217 to 255 over 255. Critical hits double level and ignore stat stages, burn, and screens.

Gen 1 battle math

Pokemon Yellow damage calculator

Roll cartridge-order damage for any Yellow matchup: Physical vs Special by type, STAB, the Gen 1 type chart (including Ghost→Psychic 0×), crit level doubling, burn/screens, and the classic 217–255 random window. Presets jump to common gym checks.

Integer Gen 1 formula STAB floor(+50%) Crit = level ×2 Rolls 217–255 110 damaging moves

Fast Answer

Level → power → Atk/Def → STAB → types → random

Yellow damage is pure integer. Build a core from level and power, divide by the defending stat, apply STAB and type multipliers (Yellow chart), then multiply by a random roll 217–255 / 255. Critical hits double level and skip stages, burn Attack cut, and Reflect/Light Screen. For save-party and full EXP tools, open the main calculators.

217–255Random roll

×1.5STAB (integer)

×2 LOn critical

0×Ghost → Psychic bug

Interactive tool

Matchup damage workbench

Open full damage suite Tune DVs first

Attacker

Attacker level Offense DV (Atk or Spc) Offense Stat Exp Offense stage (−6…+6)

Defender

Defender level Defender Attack DV (HP bit) Defender Defense DV Defender Speed DV (HP bit) Defender Special DV Defense / Special Stat Exp HP Stat Exp Defense stage (−6…+6)

Move

Move details

STAB Defender current HP (for %) Critical hit (level ×2, ignore stages/burn/screen) Attacker burned (Physical only, non-crit) Reflect / Light Screen active (non-crit)

Damage range (per hit window)

0–0

0% – 0%

Effectiveness

—

Roll	Damage	% HP

…

Save-party damage lab Dual-type matrix

Formula

What the cartridge actually does

Core pipeline

base = floor(L×2/5)+2
base = base × Power × Offense / Defense / 50
base = min(997, base) + 2

Then STAB, then each type multiplier with Gen 1 rounding, then random. If pre-random damage is 0 or 1, Yellow returns it unchanged instead of using 217–255.

Critical hits

Level is doubled inside the formula.
Ignores Attack/Defense stages.
Ignores burn’s Attack cut.
Ignores Reflect / Light Screen.
High-crit moves (Slash, Crabhammer…) raise the crit threshold—see the crits guide.

Physical vs Special

Types decide the category, not the move name. Physical → Attack vs Defense. Special → Special vs Special. Yellow has one Special stat.

Trainer defaults

Gym and trainer parties use fixed DVs Atk 9 / Def 8 / Spe 8 / Spc 8, which derives HP DV 8, and no Stat Exp. Presets load all four values; tweak freely.

Remember integer orderFloor after each major step—order matters. STAB is +50% after the +2 stepAuto when types match. Ghost does not hit Psychic0× damaging Ghost moves in English Yellow. Badge boosts are separateApply ×1.125 on the badge tool if needed. DVs change the statsUse the DV calculator for perfect rolls. Save Import for real partiesFull calculators load exact DVs/SE.

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Play tips

Using rolls in a real run

Plan around min rolls

If the minimum roll already OHKOs, the fight is free. If only max rolls KO, bring a second attack or status.

Screens and burn

Reflect/Light Screen double the defending stat before damage—unless you crit. If scaling starts with Defense ≥1024, Yellow divides by four and keeps only the low byte, creating the cartridge overflow quirk. Burn halves physical Attack unless you crit.

Multi-hit moves

Double Kick and friends roll damage per hit. The table multiplies by the move’s hit range for totals.

When to open the full suite

Need Exp curves, party import, or attacker Speed DV for OHKO accuracy? Use /calculators.

FAQ

Damage calculator questions

How does damage work in Pokemon Yellow?

Generation I integer math: level and power feed Attack/Defense (or Special), then STAB, type chart, and a 217–255 random roll.

Why do my numbers differ from a modern calc?

Modern games use different formulas, 0–31 IVs, natures, and items. This tool follows English Yellow order and the Gen 1 chart.

Does this include badge boosts?

No. Rebuild stats first (optionally with the DV tool), then multiply boosted stats using the badge boosts page if you are mid-run with badges.

Are fixed-damage moves supported?

Yes for common modes: SonicBoom (20), Dragon Rage (40), Night Shade/Seismic Toss (level), Super Fang (half HP), Psywave range, and a simplified OHKO display.

Linked tools