Koi Income Calculator
For the Roblox game Steal An Egg. Type your Koi's weight and mutations to see what it earns and how long it takes to afford your next upgrade.
Updated · game data from the wiki as of 30 September 2026 · changelog
Short answer: a Koi earns $12M per second at its base weight of 120 kg with no mutations. That is $43.2B per hour. Every doubling of its weight multiplies income by about 1.53, so a Golden Koi at twice the base weight (240 kg) earns $46M/s. Type your own Koi's weight and mutations below.
Koi at a glance
| Rarity | Cosmic |
|---|---|
| Biome or egg | Cherry Blossom |
| Base income | $12M/s · $43.2B/hour · $1.04T/day |
| Base weight | 120 kg (wiki calculator data; no second source) |
| Rank by base income | #10 of 29 Cosmic pets in our data |
| Egg grow time | 25m (wiki pet page; unverified) |
| How sure | Base income: the wiki's calculator data and the Koi wiki page agree. Steal An Egg Time lists $12M/s (matches; marked "unconfirmed" there). |
Koi income by weight
No mutations, no boosts. The size multiplier is (weight ÷ 120 kg)37/60 up to 125× base weight, then grows more slowly.
| × base | Weight | Size | Per second | Per hour |
|---|---|---|---|---|
| 1× | 120 kg | ×1.00 | $12M | $43.2B |
| 2× | 240 kg | ×1.53 | $18.4M | $66.24B |
| 5× | 600 kg | ×2.70 | $32.38M | $116.55B |
| 10× | 1,200 kg | ×4.14 | $49.64M | $178.71B |
| 50× | 6,000 kg | ×11.16 | $133.93M | $482.15B |
| 125× | 15,000 kg | ×19.64 | $235.65M | $848.36B |
| 250× | 30,000 kg | ×25.91 | $310.95M | $1.12T |
Koi income by mutation
At base weight (120 kg). With two mutations the wiki disagrees with itself on whether they add or multiply, so both are shown.
| Mutation | If they add | If they multiply |
|---|---|---|
| None | $12M/s | same |
| Silver | $14.4M/s | same |
| Golden | $30M/s | same |
| Rainbow | $42M/s | same |
| Golden + Bloom | $33M/s | $37.5M/s |
| Rainbow + Parasite | $66M/s | $126M/s |
Worked example: a Golden Koi at twice base weight
- Weight ratio: 240 kg ÷ 120 kg = 2.
- Size multiplier: 237/60 = ×1.5333.
- Golden multiplies by 2.5, so income = $12M × 1.5333 × 2.5 = $46M/s, which is $165.6B per hour.
- Saving for the Lucky Block Treadmill ($75B) from $0 with only this pet: 27m 10s. A plain Koi at base weight would take 1h 44m.
Common mistakes
- Expecting income to double with weight. A Koi at 240 kg earns $18.4M/s, not double the base. To double its income it has to weigh about 3.08 times the base: 370 kg.
- Forgetting the 125× soft cap. For a Koi that is 15,000 kg. Past it, extra weight still helps but much less: doubling from 125× to 250× adds only about 32%.
- Assuming mutations multiply. A Golden + Bloom Koi at base weight earns $33M/s if mutations add (the wiki calculator's rule) and $37.5M/s if they multiply. Plan with the lower number until it's confirmed.
- Counting the x2 gamepass twice. Tick it once. If you copy this pet's income into the treadmill calculator with x2 already included, leave x2 unticked there.
Questions
How much money does a Koi make in Steal An Egg?
At its base weight of 120 kg with no mutations, a Koi makes $12M per second, or $43.2B per hour. Heavier and mutated Kois make more: a Golden one at twice the base weight makes $46M per second.
How much is a Koi worth in Steal An Egg?
Steal An Egg has no trade window, so there's no reliable trade value. What a Koi is worth to you is the money it earns: $43.2B per hour at base weight, and more for a heavier or mutated one. Enter yours in the calculator above.
How heavy does a Koi need to be to double its income?
About 3.08 times its base weight, because income grows with weight to the power 37/60. For a Koi that is 370 kg.
What is the best mutation for a Koi?
Rainbow is the strongest hatch colour at ×3.5: a Rainbow Koi at base weight earns $42M per second. With Parasite on top it reaches $66M per second if mutations add.
Other Cosmic pet calculators
- Snowy Owl Cosmic
- Bronto Cosmic
- Triceratops Cosmic
Have more than one pet? The Steal An Egg pen calculator adds up your whole pen. Or use the weight calculator, mutation calculator, fuse calculator or treadmill calculator.