Trade IV reroll calculator
When you trade a mons in GO, its IVs reroll based on your friendship level. This tool computes the probability of hitting any target IV spread and how many trades you'd need on average. Lucky trades guarantee 12-15 floors.
At Best Friend, here's the probability of common IV targets. Use this to estimate how many trades you'd need for a re-roll project.
| Target | P(per trade) | Expected trades |
|---|---|---|
| Hundo (15/15/15) | 0.08% | 1,331 |
| Functional Hundo (14+ across) | 0.60% | 167 |
| Raid Attacker (15 ATK only) | 9.09% | 11 |
| Gym Defender (0/15/15) | 0.83% | 121 |
| 13+ across | 2.03% | 50 |
| 12+ across (Lucky floor) | 4.81% | 21 |
| 10+ across (raid catch floor) | 16.23% | 7 |
Each IV is rolled independently from the floor range. At Best Friend, each IV rolls uniformly from 5 to 15 — that's 11 possible values per stat.
P(stat ≥ target) = (16 - target) / (16 - floor). The joint probability for all three stats is the product: P(all) = P(atk) × P(def) × P(sta).
Expected trades follows the geometric distribution: E[trades] = 1 / P(all). Half the time you'll need fewer trades, half the time more — the median is around ln(2) / P(all) ≈ 0.69 × E[trades].
- ▸Trading a hundo always RESETS IVs. If you trade your hundo Mewtwo and don't roll another hundo, you've permanently lost the original.
- ▸Special trades (Legendary / Mythical / Shiny / Regional) cost more dust + are limited to 1 per day. Plan carefully.
- ▸Lucky trades are RNG — you can't force a Lucky. Trading old mons (caught before July 2018) bumps the Lucky rate.
- ▸These probabilities are independent across stats. Most players over-estimate their odds because they think "I just need one good roll" — but you need ALL THREE to hit target.
The math behind in-game trade rerolls
When you trade a mons, its IVs are re-rolled by a uniform-random distribution above the friendship floor. Lucky trades raise the floor to 12; this is the single biggest lever for chasing hundos through trade. See the Lucky trade calculator for hitting the guaranteed-Lucky window.
How to use this calculator
1. Pick your friendship level. Good / Great / Ultra / Best — or Lucky. The floor determines the per-stat minimum after the trade.
2. Set the target stats. Default 15/15/15 (hundo). Adjust if you want odds for "any stat ≥14" or a specific non-15 spread.
3. Read the per-trade probability. p = chance of hitting the target on ONE trade. Below it: expected trades = 1 / p (geometric distribution).
4. Reality-check the cost. Each trade costs stardust (depends on friendship). Multiply by expected trades to see whether grinding for a re-rolled hundo is worth it. Spoiler: usually not unless Lucky.
FAQ
What is the trade IV floor at each friendship level?
Good = 1/1/1 floor (same as wild). Great = 2/2/2. Ultra = 3/3/3. Best Friend = 5/5/5. Lucky trade = 12/12/12 across all friendship levels — guaranteed near-hundo. The floor only raises the minimum; max remains 15 per stat.
What's the probability of a hundo from a Best Friend trade?
With a 5/5/5 floor, each stat rolls uniformly from 5–15 (11 outcomes). P(15 on one stat) = 1/11 ≈ 9.1%. P(15/15/15) = (1/11)³ ≈ 0.075% — roughly 1 in 1331 trades. Lucky lifts that floor to 12/12/12, giving 1/4³ = 1.56% (1 in 64).
Should I trade a 96% IV hoping for a hundo?
Almost never. The 96% IV is already raid-ready; the probability of trading INTO a hundo is below 1% unless Lucky. You also lose the original IVs forever — there is no undo. Trade junk-IV duplicates, not your best.
How do I increase my Lucky-trade rate?
Lucky odds rise with the AGE of the older trade partner (it scales by years since the older mons was caught). Trade with friends whose oldest mons are from 2016-2018 for the highest Lucky chance. From 2020-09-01, any trade where one mons is 2+ years old is GUARANTEED Lucky.