One 2.5% chance becomes 63.7% across 40 completed raids
The calculator finds the chance of at least one Snake, not a guaranteed drop date. At the official Update 5.5 rate, 28 completions pass 50%; 40 reach 63.7%; 100 reach 92.0%.
Grow A Colony Snake Raid Chance Calculator
Calculate your chance of getting Snake after completed Grow A Colony raids using the official 2.5% drop rate, with no false guarantee at 40 or 100 raids.
Official rate: 2.5%28 raids: 50.8%40 raids: 63.7%
Independent raid model
Calculate your chance after completed raids
Enter only raids you completed. Starting or failing a raid is not described as a 2.5% attempt.
raids
Whole numbers from 0 to 10,000. The calculation stays in your browser.
40 raids are not a guarantee. At 40 completions, the modeled no-drop chance is still 36.3%.
The formula assumes every completed raid is independent and always uses the official 2.5% rate.
Formula
Why the chances do not add as 2.5% × raids
Each new attempt can only succeed if the earlier attempts did not already produce Snake.
1 · Start with the miss rate
One completion has a 97.5% chance of no Snake: 1 − 0.025.
2 · Repeat the miss rate
Raise 0.975 to the number of completed raids to model no Snake across all attempts.
3 · Subtract from one
1 − 0.975raids gives the chance of getting Snake at least once.
Reference table
Common completed-raid counts
Rounded to one decimal place for display.
| Completed raids | At least one Snake | No Snake yet |
|---|---|---|
| 1 | 2.5% | 97.5% |
| 5 | 11.9% | 88.1% |
| 10 | 22.4% | 77.6% |
| 20 | 39.7% | 60.3% |
| 28 | 50.8% | 49.2% |
| 40 | 63.7% | 36.3% |
| 50 | 71.8% | 28.2% |
| 60 | 78.1% | 21.9% |
| 80 | 86.8% | 13.2% |
| 100 | 92.0% | 8.0% |
Model boundary
Expected count is not a pity counter
The mean waiting time at 2.5% is 40 completions, but individual outcomes vary. No official guarantee, pity system, changed odds, or failed-raid rule is stated in the current public description.
Source · checked
Drop rate from the live game description
Related
Use the result in context
FAQ
Probability questions
How does the Snake Raid chance calculator work?
It uses 1 − (1 − 0.025) raised to the number of completed raids, which gives the chance of at least one success across independent attempts.
How many Snake Raids give a 50% chance?
Twenty-eight completed raids produce about a 50.8% chance under the independent 2.5% model.
Is Snake guaranteed after 40 raids?
No. Forty completions produce about a 63.7% chance of at least one Snake and a 36.3% chance of no Snake.
Can I still miss Snake after 100 raids?
Yes. The model gives about a 92.0% success chance and an 8.0% no-drop chance after 100 independent completions.
Does the calculator read my Roblox account?
No. It uses only the raid count entered in your browser and does not request a username, credential, or account connection.