How to Calculate Pet Value by Weight and Age
If you have ever stood in a trade window wondering whether a pet is worth what the other player claims, you already know why the Grow a Garden calculator exists. Pet value is not a single number stamped on the card — it is the product of weight in kilograms, age from 1 to 500, and any mutations the pet carries. Get the three inputs right and the final value becomes predictable.
The three inputs that set pet value
Before touching a calculator, understand what each field actually does to the number.
1. Weight (kg) scales linearly
Every pet has a base value expressed per kilogram. A heavier pet is simply worth more of that base: double the weight, double the value. This is the most intuitive input because the relationship is a straight line with no curve or cap in normal play ranges.
- A 1 kg Legendary and a 2 kg Legendary share the same value-per-kg — the heavier one just multiplies further.
- Weights commonly sit between 1 kg and 20 kg for trained pets; extreme values are rare.
- Always enter the actual displayed weight, not an estimated one.
2. Age (1–500) applies a gentle growth curve
Age does not add value flatly — it multiplies. A practical community curve used in our tool is:
age multiplier = 1 + (age − 1) × 0.004
That formula means age 1 is exactly ×1.000 and age 500 is roughly ×3.000. In other words, a fully aged pet is worth about three times its newborn base, all else equal. Growth is strongest in the early levels and slows in absolute terms as you climb — but never stops until 500.
| Age | Multiplier | Approx. value gain |
|---|---|---|
| 1 | ×1.000 | Baseline |
| 50 | ×1.196 | +19.6% |
| 100 | ×1.396 | +39.6% |
| 250 | ×1.996 | +99.6% |
| 500 | ×2.996 | ≈ +200% |
3. Mutations multiply aggressively
Mutations are where values explode. A Golden mutation multiplies by 20×, Rainbow by 100×, and top tiers push far beyond. Because mutations multiply after weight and age are applied, a mutated heavyweight aged pet can be orders of magnitude above a plain one. See the full tier list in our mutation multipliers guide.
The full formula
Putting it together:
Pet value = (base value per kg) × (mutation multiplier) × (weight in kg) × (age multiplier)
Optional ability boosts (for example +15% when an active skill is counted) stack on top of that total.
Worked example
Take a Mythical pet, 4.2 kg, age 120, Rainbow mutation:
- Base per kg for Mythical ≈ 140.
- Rainbow multiplier = ×100 → 140 × 100 = 14,000 per kg.
- Weight: 14,000 × 4.2 = 58,800.
- Age 120 multiplier = 1 + 119 × 0.004 = 1.476.
- Final ≈ 58,800 × 1.476 ≈ 86,789.
The same pet at age 1 would be worth 58,800 — aging alone added roughly 28,000 value. That gap is exactly why traders care about age so much.
Common mistakes
- Forgetting age: pricing a level-1 pet as if it were maxed undervalues it by up to 200%.
- Wrong weight units: entering grams or rounded display values shifts the total.
- Assuming additive mutations: mutations multiply — 20 × 100 is 2,000, not 120.
- Ignoring demand: the math gives fair value; hype can push real trades above it.
Calculate yours in seconds
Rather than doing this by hand every time, open the Pet Value calculator, choose the pet, enter kg and age, pick a mutation, and hit Calculate. The breakdown shows value per kg, the age curve, and the exact total — ready to copy into a trade message.
Frequently asked questions
What is the max pet age in Grow a Garden?
500. Our calculator caps the age field at 500 and rejects anything above it.
Does weight change as a pet ages?
In practice, weight stays stable while age raises the multiplier. Enter the current weight once and adjust only age when planning growth.
How much is a max-age pet worth compared to age 1?
About 3× the base, using the standard linear age curve described above.