Granblue Fantasy Drop Rate Calculator
Estimated rate from wiki/data (e.g., Gold Bar ~0.1-0.2%)
Boost Multipliers
None (0%)
Standard (20%)
Unite and Fight / GW (30%)
None
Drop Rate Up (5%)
Drop Rate Up (10%)
Large Drop Rate Up (20%)
Campaign Special (50%)
Combine Main + Friend summon %
None
Esser/Tien Backline (5%)
Esser/Tien Frontline (10%)
Richard (10%)
Lvl 0 (0%)
Lvl 1 (20%)
Lvl 2 (30%)
Lvl 3 (40%)
Lvl 4 (50%)
Lvl 5 (60%)
Lvl 6 (70%)
Lvl 7 (80%)
Lvl 8 (90%)
Lvl 9 (100%)
Total Boost Multiplier:
0%
Effective Drop Rate per Run:
0%
Expected Drops in 0 runs:
0
Chance to get at least 1 drop:
0%
Chance to get 0 drops (Bad Luck):
0%
Understanding GBF Drop Rates and Mechanics
Farming in Granblue Fantasy requires patience and an understanding of how drop rate modifiers interact. Unlike many RPGs where drop rate buffs might multiply consecutively, GBF generally follows an additive formula for the multiplier itself, which is then applied to the base drop rate of the chest.
The Drop Rate Formula
The community-accepted formula for determining your effective drop rate is:
Effective Rate = Base Rate × (1 + Total Boost Percentage)
For example, if a specific weapon has a 1% base drop rate and you have a total boost of 100% (from Kaguya, Crew Skills, and Journey Drops), your effective drop rate becomes 2%.
Sources of Drop Rate Boosts
- Crew Skills: Standard crew buffs usually provide a 20% boost to item drop rates. During Unite and Fight (GW), this can be upgraded to 30%.
- Journey Drops: Activated via the shop, these provide varying boosts (10% to 20%). During special campaigns, this can go up to 50% or more.
- Summons: Summons like Kaguya, Nobiyo, and the White/Black Rabbits provide significant drop rate auras. These stack if you use one as a main summon and one as a support summon.
- Weapons: Certain weapons like Oliver (Thief class weapon) or the Septian Burner provide a passive boost when equipped in the main hand.
- Treasure Hunter (Bounty): The "TH" stacks applied to enemies increase the drop rate multiplier. While exact values are often debated, TH9 is generally considered to provide a massive boost, effectively doubling the base rate in many calculations.
Cumulative Probability in Grinding
Even with a high drop rate, RNG (Random Number Generation) plays a major role. This calculator uses the binomial distribution formula P = 1 - (1 - rate)^n to determine the probability of seeing at least one drop over a set number of runs. This helps you manage expectations when farming for rare items like Gold Bars (Hihiirokane) or specific Ancestral weapons.
Blue Chests and Purple Chests
It is important to note that drop rate boosts primarily affect the appearance rate of wooden, silver, and gold chests. Special chests like Blue Chests (deal X honor) and Purple Chests (campaign drops) often have fixed appearance conditions or internal rates that are not affected by standard drop rate buffs like Kaguya or Treasure Hunter.