Pokemon Stat Calculator — Gen 1 (RBY)

Gen 1 Stat System Explained

Generation 1 (Pokemon Red, Blue, and Yellow) uses a fundamentally different stat system from modern games. Understanding these differences is crucial for retro competitive play and speedrunning.

DVs (Determinant Values)

Instead of IVs (0-31), Gen 1 uses DVs ranging from 0 to 15. The conversion is roughly DV × 2 + 1 ≈ IV, so a 15 DV is equivalent to a 31 IV. Unlike modern games, DVs for Special Attack and Special Defense are the same (they share a single "Special" DV), and the HP DV is calculated from the other DVs rather than being independent.

The HP DV is determined by whether each of the other DVs is odd or even:

HP DV = (Attack DV odd ? 8 : 0)
      + (Defense DV odd ? 4 : 0)
      + (Speed DV odd ? 2 : 0)
      + (Special DV odd ? 1 : 0)

Stat Experience

Instead of EVs (max 252 per stat), Gen 1 uses Stat Experience ranging from 0 to 65535. The square root of Stat Experience is used in the formula, so diminishing returns kick in quickly. At 65535 Stat Exp, the square root is 255 — the maximum effective value.

Unlike modern EVs, there is no total cap in Gen 1. A Pokemon can max out all six stats to 65535 Stat Exp each. This means with enough grinding, every Pokemon can reach its full potential.

Gen 1 Stat Formula

HP = floor((Base + DV + floor(sqrt(StatExp))) × Level/100) + Level + 10

Other = floor(((Base + DV + floor(sqrt(StatExp))) × Level/100) + 5)

Note: No nature modifier exists in Gen 1. All stats have neutral multipliers.

Critical Hit Rate

In Gen 1, critical hit rate is based on the Pokemon's base Speed stat, making fast Pokemon like Alakazam and Tauros crit machines. The formula is:

Crit Rate = Base Speed × 100 / 512  (normal moves)
Crit Rate = Base Speed × 100 / 64   (high-crit moves like Slash, Razor Leaf)

Special Stat

Gen 1 has a single "Special" stat that serves as both Special Attack and Special Defense. Pokemon like Alakazam (Special 135) excel at both dealing and taking special damage. This was split into two separate stats starting in Gen 2.

Strongest Gen 1 Pokemon

DV Inheritance & Breeding

In Gen 2 (which is compatible with Gen 1 via Time Capsule), DVs are partially inherited through breeding. The offspring inherits the Defense DV directly from the mother, and the Special DV is inherited with a possible ±8 deviation. The Attack and Speed DVs are randomly generated. The HP DV is then calculated from the other four DVs as described above.

Because of this system, breeding for perfect DVs in Gen 2 is much harder than breeding for perfect IVs in Gen 6+. The odds of hatching a 15 DV (perfect) Pokemon are approximately 1 in 6,552 — compared to 1 in 32 for a single perfect IV in modern games.

Gen 1 Quirks & Trivia

• 151 Pokemon: Only the original 151 are available. Many have different base stats than later generations due to the Special split.
• No natures: Natures didn't exist yet — all stats have neutral multipliers.
• No abilities: Abilities were introduced in Gen 3. Gen 1 Pokemon have no inherent abilities.
• No held items: Held items didn't exist in Gen 1 (they were added in Gen 2).
• Crit based on Speed: Fast Pokemon crit significantly more often, making Speed doubly valuable.
• No EV cap: All six stats can be maxed to 65535 Stat Exp — no trade-offs needed.
• Glitch Pokemon: MissingNo. and other glitch Pokemon have unusual stat values due to data interpretation errors.

Frequently Asked Questions