gen 1 damage calculator

What this Gen 1 damage calculator is for

If you play competitive RBY, challenge friends on retro simulators, or just love classic Pokémon mechanics, damage ranges are everything. This calculator helps you estimate exactly how hard a move can hit, from minimum roll to maximum roll, with support for critical hits, burn, Reflect/Light Screen, STAB, and type matchups.

Generation 1 can be surprisingly unforgiving. A small damage swing can turn a likely 2HKO into a shaky 3HKO. Knowing your ranges gives you better decision-making in tight endgames.

How Gen 1 damage works (quick breakdown)

At a high level, Gen 1 damage starts with:

• Attacker level
• Move base power
• Attacking stat vs defending stat
• STAB and type effectiveness
• A random damage roll from 217 to 255 (39 total outcomes)

The random roll means your move does not deal one fixed number. Instead, it lands inside a known range. In practical play, that range and its probability distribution are what matter.

Critical hits in RBY

Critical hits in Gen 1 are not just a flat multiplier from later generations. They effectively use a higher level term and bypass many stat modifications in standard play logic. This calculator models that by doubling level for the damage core and ignoring burn/Reflect penalties when critical is checked.

Burn and Reflect/Light Screen

Burn cuts physical damage output by halving effective Attack (outside crit interactions), while Reflect/Light Screen effectively doubles the target’s relevant defensive bulk in this simplified input model. These toggles let you quickly evaluate whether a defensive line survives key threats.

How to use this calculator correctly

1. Enter attacker level (typically 100 in competitive RBY).
2. Enter move power (e.g., Body Slam 85, Hyper Beam 150, Blizzard 120 in Gen 1).
3. Enter final effective Attack and Defense stats for the matchup.
4. Select type effectiveness multiplier.
5. Enable STAB, critical hit, burn, and Reflect/Light Screen as needed.
6. Optionally input target HP to get 1HKO/2HKO/3HKO odds.

Tip: If you are uncertain about exact stats, run several nearby values to understand best-case and worst-case outcomes.

Why damage ranges matter in competitive RBY

Classic Gen 1 battles often revolve around tight thresholds:

• Can Tauros secure a 2HKO without crit?
• Does Snorlax need chip before finishing with Hyper Beam?
• Can Alakazam survive and recover, or does it fold to a high roll?

These are not academic questions. They decide whether you attack, switch, set status, or play for paralysis and full-paralysis turns.

Example planning workflow

Scenario: neutral STAB attack

Suppose your attacker is level 100, using a 95 base-power STAB move into neutral typing. You can plug in expected Attack and Defense stats, then check if your target HP is in practical 2HKO territory. If 2HKO odds are low, your best line may be to spread status first, then return for cleanup.

Scenario: crit fishing

If your normal hit is a weak 3HKO but crit puts pressure on immediate KO ranges, you can estimate whether staying in is worth it. In Gen 1, crit interactions are powerful and can completely change the risk profile of a turn.

Important notes and limitations

• This page is focused on core RBY-style damage and practical battle planning.
• Edge-case cartridge quirks and overflow interactions are not fully emulated.
• You should treat output as high-quality tactical guidance, not frame-perfect hardware emulation.

For most players and most ladder games, these results are exactly the level of detail needed to make stronger decisions quickly.

Final thoughts

Damage calculation is one of the fastest ways to improve in Generation 1. Once you can identify safe ranges and likely KO lines, your mid-game choices become cleaner and your endgames become far more consistent. Bookmark this tool, test your common matchups, and build intuition one scenario at a time.