Introduction
The Uma Musume Affinity Calculator helps you build a better breeding lineage. In Uma Musume Pretty Derby, your trainee inherits from two parents (called Legacies) and four grandparents (called Sub-Legacies). How well those characters match each other is called affinity, or compatibility. Higher affinity means a better chance to pass down strong sparks, skills, and stats.
This tool does that math for you. Pick your Main Character, fill in the Legacy and Sub-Legacy slots, and the calculator scores every pair. It looks at things like shared team, running style, distance, surface, matching bloodlines, and shared G1 race wins. You get one clear affinity score from 0% to 100%, a pip rating out of 10, and a tier from Poor up to Perfect. If you like tracking gacha-style breeding math in other games, the Palworld Breeding Calculator works on a similar parent-pairing idea.
You also get a full breakdown. A table shows what each pair is worth and why. A chart shows which links help your score the most. Step-by-step math shows how the final number was found, so nothing is hidden. Under the hood it is a weighted average of every pair, turned into a percentage of the best possible total.
Then add sparks and race wins to each parent and grandparent. The calculator shows the chance each spark passes down to your trainee. Sparks marked on your Main Character are treated as goals, so you can see if your plan will work before you spend hours training. If you want to dig into the odds side of things, the Probability Calculator and the Drop Chance Calculator explain how repeated chances stack up.
Not sure who to add next? Hit Get Recommendations. The tool tests every character on your roster and tells you who raises your score the most, and by how much. You can also mark which characters you own so it only suggests ones you can actually use.
Note: the point values here are estimates meant to guide your planning. They may not match the exact numbers used in-game.
How to use our Uma Musume Affinity Calculator
Pick your trainee and her ancestors, add their sparks and race wins, and the calculator shows your affinity score, a pair-by-pair breakdown, and the chance each spark is passed down.
Main Character: Click Select in the top slot and choose the uma musume you are raising. All sparks flow down to her.
Legacy 1 and Legacy 2: Choose the two parent characters. These links count the most toward your affinity score.
Sub-Legacy slots: Fill the four grandparent slots under each Legacy. They add smaller bonuses to the total score.
Search box and "Only show owned": Type a name, team, running style, or distance to find a character fast. Tap the star next to a name to mark it as owned, then tick the box to hide the rest.
"Keep current sparks and races on swap": Leave this ticked to keep the sparks you already set when you change a character in a slot. Untick it to start that slot fresh.
Edit Sparks: Open the spark list for any filled slot, tick the sparks that character carries, and set each one to 1★, 2★, or 3★. More stars mean a better chance to inherit.
Select Races: Pick the G1 and G2 races that character won. Use the distance, surface, and grade filters to narrow the list, then hit Confirm.
Calculate: Press this to update the score, the charts, and the step-by-step math.
Get Recommendations: Press this to see which characters would raise your affinity the most, and place them with one click. The change in score is shown as a plus or minus figure, the same way a Percent Change Calculator compares before and after.
Reset All: Clears every slot, spark, and race so you can plan a new lineage.
What Is Uma Musume Affinity?
Affinity is a hidden compatibility score between the trainee you are raising and her two parents (called Legacies or inherits), plus their four parents (Sub-Legacies or grandparents). In Uma Musume Pretty Derby, this score decides how often sparks get passed down during training. A high affinity means more sparks, better stats, and stronger skills for your new uma.
How the Lineage Tree Works
Every trainee has seven spots in her family tree:
- Main Character - the uma you are training now.
- Legacy 1 and Legacy 2 - her two parents. These matter the most.
- Four Sub-Legacies - the grandparents. They add smaller bonuses.
The game checks the link between the trainee and each parent, and the link between the two parents. Grandparents count too, but less. Each link is worth points, and the points are added up to make one final score. If you have ever mapped out inherited traits with a Punnett Square Calculator, the idea of tracing traits back through parents and grandparents will feel familiar.
What Raises Affinity
Points come from things the characters share, such as:
- Shared G1 race wins - the biggest boost. Two umas that both won the Arima Kinen or the Japan Cup have a strong link.
- Same bloodline or story group - like the Mejiro family or Triple Crown winners.
- Same team - Spica, Rigil, or Canopus.
- Same running style, distance, or surface - small but helpful bonuses.
Rival pairs can lower the score, and using the same character twice gives you nothing.
Affinity Pips and Tiers
In game, affinity shows as pips (small circles) on the inherit screen. More pips means better odds. A score under 20% is Poor, and anything over 80% is close to Perfect. Most players aim for the highest pips they can get before starting a run. Rounding the raw percentage into pips uses the same idea as a Rounding Calculator, so a 74% and a 75% can land on different pip counts.
Sparks and Inheritance
Sparks are the blue (stat), pink (aptitude), green (unique skill), white (skill), and race sparks your parents carry. Each spark has a star rating from 1 to 3. Higher stars and higher affinity both raise the chance that a spark is passed to your trainee. Parents pass sparks more often than grandparents do. When two ancestors both carry the same spark, the tool combines their odds the way a Shiny Odds Calculator handles repeated chances: it works out the chance of missing every time, then flips it around.
Why It Matters
Good affinity is one of the cheapest ways to make a stronger uma. Picking parents that raced together or share a bloodline can turn a normal run into a career-best run. If you are building a team for Team Trials or Champions Meeting, planning your lineage before you train saves a lot of time and stamina. Players who plan resource spending across other gacha titles often pair this with the Genshin Pity Calculator or the Genshin Wish Calculator for the same reason: know the odds before you commit.
Note: point values here are estimates. They show how affinity works but may not match the exact numbers used inside the game.