The Complete Guide to Uma Musume Affinity (相性) — Maximise Your Training Results
A comprehensive, humanised guide to understanding Uma Musume Pretty Derby affinity mechanics, how the 相性計算 (affinity calculation) works, and how to use our free calculator to build unbeatable training pairs and race-winning teams.
What Is Affinity (相性) in Uma Musume Pretty Derby?
In Uma Musume Pretty Derby, affinity (相性, ai-shō) is a hidden compatibility score that measures how well two Uma Musume characters work together during training and racing scenarios. When you pair two Uma Musume with high mutual affinity, both characters receive bonus stat growth, enhanced skill activation rates, and improved race motivation — collectively giving them a measurable competitive advantage over pairs with lower compatibility scores.
Affinity is not a simple fixed value. It is computed from a combination of factors: shared race aptitudes (距離適性), overlapping special skills (固有スキル), complementary stat archetypes, historical racing relationships drawn from real-world horse racing lore, and in some versions of the game, story-based relationships that unlock affinity boosts. Understanding all these layers is what separates casual players from top-ranked trainers in competitive play.
How the Uma Musume Affinity Calculator Works
Our calculator provides four interconnected tools for comprehensive affinity and team planning, all based on the game's publicly documented mechanics.
💕 Affinity Check Mode
Select two Uma Musume from the full roster and instantly receive a compatibility score out of 100, an affinity grade (C through SS), skill synergy count, stat bonus percentages for each stat type, race aptitude coverage, and personalised support card recommendations. Results update in real-time as you change selections.
👥 Team Builder Mode
Build a team of up to 6 Uma Musume and calculate the aggregate team affinity score. The team analyser shows pairwise affinity between all members, highlights the strongest and weakest bonds, calculates total team stat distribution, and provides an overall race coverage percentage across all distance classes.
⚖️ Compare Stats Mode
Place two Uma Musume in a side-by-side statistical comparison table covering base stats (Speed, Stamina, Power, Guts, Wisdom), race distance aptitudes (Short/Mile/Middle/Long), track surface aptitudes, and key skill sets. Each stat cell highlights which Uma has the advantage, helping you understand their complementary strengths.
📋 Full Roster Mode
Browse the complete Uma Musume roster with searchable name filtering and type filtering (Speed/Stamina/Power/Wisdom). Each roster card shows the character's emoji avatar, Japanese name, English name, primary stat type, and race distance aptitudes at a glance — the perfect reference for planning before entering Affinity Check mode.
Who Can Benefit from the Affinity Calculator?
Uma Musume Pretty Derby is deceptively deep, and the affinity system rewards players who invest time in understanding it. Here's who gains the most from our calculator:
✔ Competitive Ranked Players
In competitive Champion's Meeting (チャンピオンズミーティング) and Legends Race (レジェンドレース) modes, the stat and skill differences between high-affinity and low-affinity pairings can mean the difference between the top podium and a mid-table finish. Every percentage point of stat bonus matters at the highest ranks.
✔ New & Returning Players
The affinity system is not well-explained in-game, and new players often miss out on significant stat bonuses by pairing characters randomly. Our calculator makes affinity immediately accessible — no prior knowledge required. Just pick characters and see who works best together before committing training resources.
✔ Content Creators & Wiki Writers
Streamers, YouTubers, and wiki contributors covering Uma Musume use affinity data to inform tier lists, training guides, and character showcases. The downloadable report and ZIP features make it easy to document results for video thumbnails, guide articles, or community Discord posts.
✔ Gacha Planning & Resource Management
Before spending gems (ジュエル) on gacha rolls, savvy players check which new Uma Musume characters have high affinity with units they already own. Our roster view and affinity check together reveal whether a newly released character would meaningfully improve your existing roster or simply duplicate what you already have.
Affinity Grades Explained — C Through SS
The affinity system uses a grade scale from C (poorest) through SS (best). Each grade threshold determines the magnitude of synergy bonuses applied during shared training sessions:
SS Grade (90–100): Perfect Harmony
The rarest and most powerful affinity tier. SS pairs typically share deep narrative connections in the game's lore, complementary race specialisations, and multiple overlapping support skills. Stat bonuses reach their maximum values, and shared training events trigger with significantly higher frequency. Examples include historically linked racing pairs.
A Grade (70–89): Strong Synergy
Excellent compatibility that most competitive players aim for when SS is not achievable with their current roster. A-grade pairs produce reliable stat bonuses across multiple categories, share at least 2–3 key skills, and cover each other's weaker race distances effectively. The most commonly recommended tier for serious players.
B Grade (50–69): Moderate Compatibility
Adequate for casual play and story mode progression, but not optimal for competitive ranked content. B-grade pairs provide minor stat bonuses and some skill overlap. Best used when roster limitations prevent access to higher-affinity pairings, or as temporary bridges while building toward stronger combinations.
C Grade (0–49): Poor Pairing
Minimal affinity bonuses with little to no skill synergy. C-grade pairs should be avoided for competitive content. If your available characters only produce C-grade affinity, it is worth reconsidering your training scenario character selection or prioritising rolls for characters with better natural synergy with your main Uma Musume.
The Skill Synergy System — Why Shared Skills Matter
Skill synergy is one of the most impactful but least-understood aspects of the Uma Musume affinity system. 🌸 When two Uma Musume share related skills — either the same skill or skills in the same category (e.g. both having speed-burst skills, corner acceleration skills, or recovery skills) — they generate a compounding bonus during training sessions that goes beyond what either character could achieve independently.
Who Benefits Most from High Skill Synergy?
- ➤Speed-type Uma Musume: Characters specialising in short and mile distances benefit enormously from shared acceleration and burst-speed skills, since these apply in the crucial final straight of most races.
- ➤Stamina-type Uma Musume: Long-distance specialists who share recovery and pace-maintenance skills can sustain competitive speeds far longer than solo trainers, making the final stages of 2400m+ races significantly less taxing.
- ➤Mixed-type pairs: A speed-type paired with a wisdom-type can create unique synergies where the wisdom character's prediction skills boost the speed character's positioning, creating an overall race IQ bonus that neither character possesses alone.
- ➤Story-linked pairs: Certain Uma Musume have canonical racing relationships from real horse racing history. These narrative bonds unlock unique "friendship skills" that only activate when the pair trains together, providing bonuses unavailable through any other pairing.
Stat Bonus Mechanics — How Affinity Boosts Your Numbers
The five core stats in Uma Musume — Speed (スピード), Stamina (スタミナ), Power (パワー), Guts (根性), and Wisdom (賢さ) — are all affected by affinity, but not equally for all pairs:
⚡ Speed Bonus
Highest bonus for pairs sharing short/mile distance aptitude. Speed synergy directly impacts final straight acceleration and sprint burst timing, making it the most race-visible stat bonus. SS-grade pairs can receive up to +12% speed growth per training session in optimal conditions.
💧 Stamina Bonus
Most impactful for middle and long-distance pairs. Stamina synergy extends the effective stamina pool, reducing the risk of exhaustion before the final stretch. Pairs with overlapping recovery skills see compounding stamina benefits that stack multiplicatively rather than additively.
💥 Power & Guts Bonus
Power determines acceleration and cornering ability; Guts provides race-day resilience and comeback mechanics. Pairs that complement each other in these stats create Uma Musume that can overtake efficiently from the outside lane and recover from poor starting positions more effectively.
🌟 Wisdom Bonus
Wisdom affects race skill activation rate and position-reading ability. High wisdom synergy between a pair means both characters activate their conditional race skills more frequently and correctly predict when to deploy speed bursts — translating raw stat numbers into more consistent race outcomes.
Why Affinity Calculation Matters for Competitive Play
At casual difficulty, many players clear story content without ever consciously thinking about affinity. But in competitive ranked modes — particularly the Ranked PvP events introduced in later game updates — the difference between a well-optimised affinity pair and a random selection can amount to 🏆 50–100 total stat points by the end of a training scenario. At the top percentile of competitive play, this is frequently the entire margin between victory and defeat.
Key Features of Our Advanced Uma Musume Affinity Calculator
Built for serious Uma Musume trainers who want data-driven decisions, not guesswork.
Full 35+ Character Roster
Our database includes all major Uma Musume characters with accurate base stats, race distance aptitudes, primary skill categories, and narrative relationship data. Characters are regularly reviewed to ensure accuracy with the latest game version.
Multi-Mode Analysis
Four dedicated tools — Affinity Check, Team Builder, Stat Compare, and Full Roster — each answering a different strategic question. The Affinity Check is for pair optimisation; Team Builder for full roster analysis; Stat Compare for character evaluation; Roster for exploration and search.
100% Private & Browser-Based
All calculations happen entirely within your browser using JavaScript. No game account data, no personal information, and no pairing preferences are ever transmitted to any server. Works fully offline once the page has loaded — ideal for players in regions with restrictive internet access.
Downloadable Reports & ZIP Export
Generate a full printable affinity analysis report for any pair, including the affinity score, grade, skill synergies, stat bonuses, and support card recommendations. Download individual reports or batch-export multiple saved analyses as a ZIP archive for documentation or community sharing.
Pro Tips for Using the Uma Musume Affinity Calculator
The biggest affinity mistake players make is beginning a training run and only realising mid-way that their pair has poor compatibility. Use the Affinity Check tab before each scenario to confirm your chosen pair is at least A-grade before investing training resources. A 5-second check can save hours of wasted progress.
Use the Race Distance filter in Affinity Check to find pairs that specifically excel at the distance class of your upcoming race target. A pair with good overall affinity but poor specific-distance aptitude overlap will underperform compared to a slightly lower-grade pair that both specialise in the relevant distance.
The Support Card Recommendations section in the results shows which support cards will amplify the specific synergies of your chosen pair. Equipping these recommended cards transforms a good affinity pair into an exceptional one by multiplying the existing synergy bonuses rather than adding random unrelated bonuses.
When evaluating several potential pairs, save each result using the "Save Result" button, then download the entire history as a ZIP archive. This gives you a side-by-side reference document of all your considered pairings — invaluable when making the final decision about which pair to commit to for a high-stakes ranked event.
Frequently Asked Questions
Conclusion
The affinity system (相性) is one of the most rewarding strategic layers in Uma Musume Pretty Derby — and one of the most overlooked by casual players. Our free Uma Musume Affinity Calculator removes the guesswork entirely, providing instant, data-driven affinity scores, skill synergy analysis, stat bonus projections, and support card recommendations for every possible pair in the roster. Whether you're preparing for a ranked Championship event or simply optimising your story-mode training runs, make affinity calculation part of every training decision.
Ready to Find Your Perfect Uma Musume Pair?
Use our advanced Affinity Calculator now — instant results, skill synergy breakdown, team builder, and downloadable training reports, all completely free!