Uma Musume Affinity Calculator
In Uma Musume: Pretty Derby, the concept of Affinity (also referred to as “compatibility” or “legacy affinity”) is one of the most crucial yet often misunderstood mechanics — particularly if you’re delving deep into the Career Mode, legacy inheritance, or planning advanced builds. A good “Affinity Calculator” is your essential tool for making sense of this hidden system and optimizing your selections for parent and grandparent Uma Musume, all to maximise inheritance success and spark yields.
In this comprehensive guide you’ll learn exactly what affinity is, how it is calculated behind the scenes, the factors that influence it, how to use an Affinity Calculator to your advantage, and ultimately how you can apply that knowledge to build stronger trainers with predictable inheritance outcomes.
What is Affinity in Uma Musume?
Affinity in Uma Musume refers to the compatibility score between the trainee Uma you are raising and her selected legacy — that is, the parent Uma and the sub-legacies (grandparents) you choose when starting a Career. This compatibility score determines how likely you are to obtain strong inheritance bonuses — such as stat boosts, Sparks of Inspiration, skill inheriting hints, and better positioning in your training outcomes.
Put simply: your inheritance and training success depend not only on the qualitative strength of the legacies (e.g., their stars, their unique skills) but also on how well they match with your main trainee’s build. High affinity → better inheritance → greater chance of obtaining high-tier Sparks and advantageous stats. Low affinity → wasted runs, sub-par inheritance, and slower progression.
Affinity is hidden in the UI for the most part; in the legacy menu you might see symbols like △ (triangle), ○ (circle), or ◎ (double-circle) indicating low, moderate or high affinity levels. These symbols correspond to underlying numerical thresholds — but the exact numeric values are not displayed in-game.
Why Affinity Matters
If you’ve ever wondered why two very strong legacy Umas sometimes produce vastly different outcomes when used as parents, the missing piece in the puzzle is usually affinity. Here’s why it matters:
- Sparks of Inspiration & Stat Bonuses – During a Career run, “Sparks of Inspiration” events are key moments where your trainee can receive bonus stat increases or skill inheritance opportunities. High affinity significantly raises the chance that those sparks appear and are of a higher tier.
- Inheritance of Unique Skills and Aptitude – When you retire a parent (legacy) or check inheritance outcomes, your trainee can inherit unique skills (white sparks) or green/blue sparks from legacies. The higher your affinity with those legacies and sub-legacies, the better the chances
- Efficiency of Career Runs – In later stages of the game (for example when aiming for top-tier Sparks, 9★ or more), you cannot afford to waste runs. Having high affinity helps your runs be more predictable, which is critical for advanced builds, loops and “legacy chains”.
- Avoiding Weak Outcomes – If you use legacies haphazardly without paying attention to their affinity with your trainee, you may end up with very low inheritance boosts — even if you had top support cards or rare parents. As one guide puts it: “Poor affinity can wreck your build even with good support cards.”
In short: affinity is a multiplier to your inheritance system. It isn’t everything, but it’s absolutely one of the most important levers you can control.
How Affinity is Calculated — The Mechanics
Although the game does not fully disclose all its internal formulas, the community has reverse-engineered the key elements. Using this knowledge, Affinity Calculators provide a numerical “base score” and help you approximate whether you’ll hit the higher thresholds (circle ○ or double circle ◎) before investing resources. Below are the major components of affinity:
1. Hidden Compatibility Groups
Every Uma Musume is classed in one or more “hidden groups” or “compatibility groups”. If your main trainee and a selected legacy share one of these groups, the affinity score increases by the group’s point value. If the legacy and its sub-legacy also share that group, additional points are added.
For example: you pick your trainee Uma A, and legacy Uma B belongs to Group X of value “2”. Since A and B both belong to Group X, you get +2 points. Then you check B’s sub-legacy C; if C also belongs to Group X, you get another +2. Finally, if both legacies share the group, you may get yet another bonus.
2. Matching Race Wins (G1/Graded Races)
A major affinity booster comes from legacies and sub-legacies that share wins in major races (G1 in JP version; graded races in global version). If the parent and grandparent (or both parents) have won the same race, the calculator adds bonus affinity points for each such shared win.
In many calculator you’ll see +3 per shared G1 win (JP version) or +1 per shared graded race (Global server) as part of the bonus calculations.
3. Matching Specialisations: Distance, Strategy, Surface
Some guides suggest that Umas whose running style (Leader, Pacemaker, etc.), distance aptitude (mile, middle, long), turf/dirt preference, or base stats align better will contribute to higher affinity. While this is not always concrete in all cases, the trend is confirmed in guides.
4. Same Character/Version Penalty
If your legacy or sub-legacy uses the same character name as your trainee (i.e., you are training the same character as a parent or grandparent), you receive 0 affinity for that relationship. In other words, self-grandparenting is penalised.
5. Numerical Thresholds and Symbols
Affinity calculators typically display the following thresholds:
- △ (Triangle) – Poor affinity; low inheritance boost
- ○ (Circle) – Good affinity; solid boosts
- ◎ (Double Circle) – Excellent affinity; best inheritance chances
Often, the rule of thumb is:
- Score under ~60 → △
- Score between ~60-150 → ○
- Score ≥150 → ◎
But note that actual thresholds may vary by version/server.
How to Use an Affinity Calculator
An Affinity Calculator is a spreadsheet or web-tool where you input your trainee, your two legacies (parents), and optionally their sub-legacies (grandparents). It calculates the base affinity score and indicates whether you are likely to hit a circle or double-circle rating.
Here’s how to use it effectively:
- Identify your trainee Uma – Choose the race type you want to build (e.g., long turf, medium dirt) and select the main Uma you want to raise.
- Select Legacy parents – Pick two Umas you have available who will act as parents. These may come from your previous generations or from borrowed legacies.
- Select sub-legacies (grandparents) – For each parent you pick, you can often pick 2–3 sub-legacies. Input them if your calculator supports it.
- Input all necessary fields – In the tool you’ll choose “Main Uma”, “Parent A”, “Parent B”, “Sub-legacy A1”, “Sub-legacy A2”, “Sub-legacy B1”, “Sub-legacy B2”.
- Run the calculation – The tool will compute base score + group matches + race win bonuses and display your approximate score and symbol (△/○/◎).
- Interpret the result – If you get ◎ (double circle), you’re well set. If you’re close (e.g., 140–149), you may still be okay. If you’re in the △ zone (e.g., under 60), you should rethink your selections.
- Make adjustments – If the score is too low, you can swap out one parent or sub-legacy, try matching groups, pick Umas with shared G1 wins, or avoid using same-character duplicates. Then re-calculate.
Many community sites such as the example Affinity Calculator from GameTora provide drop-down menus to help with selection.
Practical Strategy: Building for High Affinity
Here’s a strategic approach you should follow to maximise your affinity and inheritance result:
A. Choose compatible legacies first
Focus on legacies whose specialisations (distance, surface, strategy) closely match your trainee. This sets a good foundation for inheritance without relying solely on sparks.
B. Prioritise hidden group overlaps
Use tools or community lists to find Umas whose hidden groups overlap. If you don’t have full lists, you can prioritise best-known matchups (often Umas within the same distance tier or those known for cooperation in story events).
C. Aim for shared G1/graded race wins
One of the highest boosts to affinity comes from shared race wins. If both your parent and grandparent have victories in the same G1 races (or graded races on Global), you’ll get big bonuses. Use this as a tie-breaker for legacy selections.
D. Avoid self-grand parenting
Make sure your grandparent is not the same character as your trainee. That causes zero bonus from that legacy link.
E. Tool verification before running
Before you commit to a high-resource career run, plug your setup into the Affinity Calculator and ensure at least ○ (circle) and ideally ◎ (double circle). Wasting runs on △ setups will cost you time and Sparks.
F. Build loops for late-game
In endgame content, players often create “loop” setups where each generation reuses Umas with high affinity legacy combinations to preserve inheritance and accumulate high-tier Sparks. For loops you need consistently ◎ setups.
Example Walk-through
Let’s walk through a hypothetical example:
- Trainee: Uma A (Long distance specialist)
- Parent 1: Uma B (Long distance specialist)
- Parent 2: Uma C (also long distance)
- Sub-legacies (Grandparents): Uma D, Uma E, Uma F, Uma G
You input these into the tool.
- It checks hidden group overlaps (e.g., if all five share Group X).
- It then checks if B & C both also share Group Y with the trainee.
- It checks if D/E/F/G are part of the groups.
- It adds bonus points if B and D, or C and F have shared G1 race wins.
- Result: Score = 172, symbol = ◎ (double circle).
Conclusion: You’re set for a high-affinity inheritance run, giving you strong chances for 3★ Sparks and high inheritance stat boosts.
Frequently Asked Questions (FAQs)
What is the Uma Musume Affinity Calculator?
The Uma Musume Affinity Calculator is a tool that helps players determine the compatibility between their trainee Uma Musume and chosen legacy parents or grandparents. High affinity increases the chance of stronger inheritance, better stat boosts, and powerful Sparks during training.
How does affinity work in Uma Musume: Pretty Derby?
Affinity measures how compatible a trainee is with her parent and grandparent legacies. It’s based on hidden groups, shared G1 race wins, distance types, and running styles. Higher affinity (○ or ◎) results in more effective inheritance events and improved performance outcomes.
What affects the affinity score the most?
Affinity scores are influenced by shared compatibility groups, common race wins, similar running styles, and distance preferences. Avoid using the same character name as both trainee and parent, as it gives zero affinity points.
What do the symbols △, ○, and ◎ mean in the calculator?
These symbols represent the level of compatibility:
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△ = Poor affinity (low inheritance boost)
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○ = Good affinity (solid inheritance rate)
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◎ = Excellent affinity (highest inheritance potential)
Aim for ◎ whenever possible for best results.
Can I improve affinity without changing parents?
Not directly. Affinity is fixed based on legacy selection. To improve it, swap parents or sub-legacies to find ones that share more compatibility groups or race victories with your trainee.
Does affinity affect support cards or training results?
Affinity does not change how support cards function. However, it indirectly boosts your training success by improving inheritance events, which means higher base stats and more efficient training outcomes.
Why do some combinations show low affinity even with strong parents?
Even if both parents are powerful, if they don’t share compatibility groups or race wins with your trainee, their affinity will be low. Using an Affinity Calculator helps identify which legacies actually synergize best.
