If you are playing Uma Musume Pretty Derby and want to build the most powerful horse girl possible, understanding the legacy system is absolutely essential. The Uma Musume Legacy Calculator is a powerful tool that helps you plan exactly which parents and grandparents to use, predict your inherited stats, calculate affinity scores, and maximize your chances of getting coveted blue (3★) factors.
In this complete guide, you will learn how the legacy inheritance system works, what compatibility symbols mean, how to interpret sparks, and how to use a legacy calculator to plan the perfect 9-star build from the ground up.
🎮 What is Uma Musume Pretty Derby?
Uma Musume Pretty Derby is a mobile and PC game developed by Cygames in which players train anthropomorphized horse girls (Uma Musume) based on real racehorses, guiding them through training scenarios to become champion racers. The game combines RPG training elements, story, and live musical performances.
A central pillar of the late-game progression system is the Legacy (Inheritance) System — a mechanic that allows trained veteran Uma Musume to pass down stat factors, skills, and compatibility bonuses to a new trainee. Optimizing this system is what separates casual players from competitive ones, and it is exactly where the Uma Musume Legacy Calculator proves its worth.
🧬 What is the Uma Musume Legacy System?
The Legacy System — also called the Inheritance System — allows a new trainee Uma Musume to inherit stat bonuses and factors from up to two veteran Uma Musume (called Legacies or Parents), and their respective sub-legacies (Grandparents).
📌 Legacy Structure Overview
- Main Trainee: The Uma Musume you are actively training in the current Career
- Legacy 1 & Legacy 2 (Parents): Two veteran Uma Musume whose stats and factors are inherited
- Sub-Legacies (Grandparents): SL 1-1, SL 1-2, SL 2-1, SL 2-2 — each parent's own legacies, contributing additional inherited bonuses
- Guest Legacy: A borrowed legacy from another player's veteran, providing a third source of inheritance
At the start of every Career run, the stat bonuses from all legacies and sub-legacies are added together as a starting bonus for the trainee. The Uma Musume Legacy Calculator calculates exactly how much stat boost you will receive from each source before you even begin training.
🔢 How Does the Uma Musume Legacy Calculator Work?
The Legacy Calculator analyzes the stats, star ratings, compatibility, and spark history of your selected Legacies to give you a precise breakdown of what your trainee will inherit. It saves hours of manual calculation and helps you identify the most efficient parent-grandparent combinations.
+ (Sub-Legacy 1-1 Stars × Weight) + (Sub-Legacy 1-2 Stars × Weight)
+ (Sub-Legacy 2-1 Stars × Weight) + (Sub-Legacy 2-2 Stars × Weight)
+ Compatibility Bonus + G1 Spark Bonus
For example, if Legacy 1 has 3★ Speed, Legacy 2 has 2★ Speed, and all four sub-legacies have 1★ Speed, the total Speed bonus to the trainee would be 21 + 12 + 5 + 5 + 5 + 5 = 53 points. Tracking all of this manually is error-prone — the calculator handles it instantly.
⭐ Understanding Blue, Pink & Green Sparks (Factors)
When a veteran Uma Musume is trained to high stat levels, they can generate sparks — colored stars that are passed to the trainee as inheritance factors. These sparks are one of the most important things to optimize using the Legacy Calculator.
Blue Spark (★ Factor)
Stat bonus inherited. Requires 1100+ stat points with ~20% chance at 1100, rising to 50% at 1200+. Up to 3★ possible.
Pink Spark (Aptitude)
Improves track type, track length, or race strategy aptitude. Every girl gets one pink spark — always one her character prefers.
Green Spark (Skill)
Transfers a skill hint from parent to trainee, giving skill unlock advantages during training runs.
🔵 How to Guarantee Blue (3★) Factors
- Train the Legacy to 1100+ stat points in the desired stat (Speed, Stamina, Power, Guts, or Wisdom)
- At 1100, the blue factor chance is ~20%. At 1150, it rises to ~35%. At 1200+, it reaches the 50% cap
- Scenario end-of-training bonuses count — Grand Masters adds ~200 stat points, often pushing stats over blue thresholds
- The Legacy Calculator shows exact probabilities based on your current stat totals so you never waste a training session
💞 Legacy Compatibility & Affinity Explained
Compatibility — also called Affinity — measures how well a legacy matches with the trainee. Higher compatibility unlocks better inheritance bonuses, more factor slots, and improved spark chances. The Uma Musume Legacy Calculator automatically evaluates and displays the compatibility symbol for your selected pairing.
Highest compatibility. Doubles blue factor inheritance rates and increases total factor slots. Ideal pairing.
Good compatibility. Standard inheritance bonuses and factor slots. Solid but not optimal.
Reduced or no affinity bonuses. Avoid these pairings when planning a serious build.
📊 What Affects Compatibility Score?
| Factor | Effect on Compatibility | Points Added |
|---|---|---|
| Historical Relationship | Real-world rivalry or partnership between horses | High boost |
| Blood Relation | Shared lineage between characters | High boost |
| Shared G1 White Sparks | Same G1 race win spark across 2 parents/grandparents | +3 per shared pair |
| Shared G1 Sparks (3 of 4) | Three of the four parents/grandparents share a G1 spark | +6 |
| Shared G1 Sparks (all 4) | All four parents/grandparents share a G1 spark | +9 |
| Aptitude Alignment | Matching track type and length preferences | Moderate boost |
| Sub-Legacy Synergy | Compatible grandparent pairings | Variable |
Achieving a score of 150+ is generally needed for a Double Circle (◎) result. Our Legacy Calculator scores your entire roster and flags the highest-compatibility combinations automatically.
🌟 How to Build a 9-Star Legacy (Step-by-Step)
A 9-star build means getting 3★ blue factors in three different stats — the gold standard in Uma Musume endgame optimization. Here is the proven roadmap, streamlined with the help of a Uma Musume Legacy Calculator:
Step 1 – Borrow a Strong Guest Legacy
Find friends in your server who have 9★ veterans with blue factors (3★) in three or more stats. You can borrow up to 3 guest legacies per day. A great guest legacy covers one-third of your inheritance work before training even begins.
Step 2 – Train Your Own Legacies to 1100+ Stats
Train your personal Legacy 1 and Legacy 2 until the stats you want (e.g. Speed and Stamina) exceed 1100 points. Remember that Grand Masters' end bonuses add approximately 200 points — plan your stopping points accordingly using the Legacy Calculator.
Step 3 – Win G1 Races to Build Shared Sparks
After reaching satisfactory stats, focus your legacies on winning G1 races. Shared G1 white sparks between your parent and grandparent characters significantly increase compatibility scores and unlock better affinity bonuses for the trainee.
Step 4 – Verify Compatibility Before Starting Career
Before launching a Career run with the trainee, use the Uma Musume Legacy Calculator to confirm you are getting a Double Circle (◎) pairing with your selected Legacy 1, Legacy 2, and guest. If not, adjust sub-legacies or look for a better guest match.
Step 5 – Run the Career and Collect Factors
With high-stat legacies and Double Circle compatibility, run the trainee's Career. Your inherited stat bonuses will give her an immediate head start, and the blue factor chances will be maximized. Repeat and chain legacies to progressively improve the gene pool across generations.
📊 Legacy Star Rating & Stat Bonus Table
| Star Rating | Parent Bonus (each) | Sub-Legacy Bonus (each) | Total (2 Parents + 4 Sub) |
|---|---|---|---|
| 1★ | +5 | +3 | ~22 pts |
| 2★ | +12 | +5 | ~44 pts |
| 3★ | +21 | +7 | ~70 pts |
| Mixed | Varies | Varies | Calculated by tool |
These values are additive per stat category. If multiple legacies contribute to the same stat (e.g. all have Speed stars), all bonuses stack. The Uma Musume Legacy Calculator totals all six sources automatically so you see the exact inherited stat boost before committing to a run.
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⚠️ Common Mistakes to Avoid When Using Legacies
| # | Mistake | Why It Hurts | Fix |
|---|---|---|---|
| 1 | Stopping training at 1090 stat points | Just below the 1100 threshold — no blue factor | Always push to 1100+ (use Legacy Calculator to confirm) |
| 2 | Ignoring sub-legacies | Misses significant compatibility and stat bonuses | Always check and fill all four sub-legacy slots |
| 3 | Using low-affinity pairings | Fewer factor slots, weaker spark inheritance | Use the calculator to verify Double Circle (◎) before running |
| 4 | Skipping G1 races for legacies | Fewer shared sparks → lower compatibility scores | After stat training, race in G1 events to accumulate race sparks |
| 5 | Not borrowing guest legacies daily | Wastes a free inheritance source (3 borrows/day) | Check friends' rosters daily and borrow the best available guest |
| 6 | Forgetting scenario end bonuses | Miscalculates final stat totals (Grand Masters adds ~200) | The Legacy Calculator accounts for scenario bonuses automatically |
❓ Frequently Asked Questions
💡 Pro Tip: Chain Your Legacies for Compounding Gains
The most effective Uma Musume players create legacy chains — where the offspring of one strong legacy becomes the parent for the next generation. Over several generations, this compounds the stat bonuses and factor quality dramatically. Use the Uma Musume Legacy Calculator at each stage to track your cumulative progress and identify which stat is ready to unlock a 3★ blue factor next.
🏇 Start Optimizing Your Legacy Build Today
Use our free calculators to build the perfect Uma Musume team and dominate every race!
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