Zombie Invasion Calculator
Simulate a zombie outbreak with adjustable populations, fighting skills, and infection rates. See how long humanity survives against the undead with interactive charts.
About This Calculator
The Zombie Invasion Calculator simulates a zombie outbreak using a dynamic predator-prey population model. Adjust parameters for both humans and zombies to explore different outbreak scenarios and discover which survival strategies work best. Will humanity prevail or fall to the undead horde?
The simulation runs day by day, tracking how many humans and zombies remain. Each day, zombies attack humans based on their attack frequency. Humans react according to their chosen defense stance — some flee while others fight. Fleeing humans may be caught depending on zombie speed. Humans who fight may kill zombies or be killed themselves. Killed humans may transform into new zombies based on the transformation probability, spreading the infection further.
Zombies can also die in combat or from starvation if that option is enabled. The simulation stops when either population drops below 0.01% of its initial size, determining whether humans survived or went extinct. The model includes a stochastic rounding element that introduces randomness, making each simulation run unique even with the same parameters.
Key Parameters
- Human Defense Stance — controls the balance between fleeing and fighting when encountering zombies
- Human Fighting Skill — rate how effective humans are at killing zombies, based on famous movie survivors
- Transformation Probability — how often a bitten human turns into a zombie
- Zombie Speed — determines how many fleeing humans get caught
- Resurrection Rate — how often seemingly killed zombies get back up
- Starvation — whether and how quickly zombies die without food
Survival Tips
To maximize human survival, try combining a fighting stance with high fighting skills, low transformation probability, slow zombie speed, and starvation enabled. Even with optimal settings, the inherent randomness means outcomes may vary — run multiple simulations to test different strategies and see which configuration gives humanity the best chance against the zombie apocalypse.
Frequently Asked Questions
How does the Zombie Invasion Calculator work?
The calculator simulates a zombie outbreak day by day using a predator-prey model. Each day, zombies attack humans, some humans flee or fight, and the populations evolve based on combat skills, transformation probability, resurrection rate, and starvation. The simulation continues until one population drops below 0.01% of its initial size.
What parameters can I adjust in the zombie outbreak simulation?
You can set initial human and zombie counts, human defense stance (flee vs fight behavior), human fighting skill level based on movie characters, zombie transformation probability, attack frequency, resurrection rate, zombie speed, and whether zombies can starve.
Is this zombie apocalypse calculator free to use?
Yes, the Zombie Invasion Calculator is completely free to use with no registration required. You can share your simulation results via URL.
What does the human defense stance do in the zombie simulation?
Human defense stance determines what percentage of humans flee when encountering a zombie versus fighting. Always Flee means 100% try to escape, while Get All the Zombies means everyone fights. Those who flee may be caught depending on zombie speed.
How does zombie speed affect the outbreak simulation?
Zombie speed determines how many fleeing humans get caught. Fast zombies catch 100% of fleeing humans, moderate catch 60%, and slow catch 30%. Faster zombies increase human death rates and accelerate the outbreak.
What happens if zombies can starve to death?
When starvation is enabled, zombies die at a daily rate based on the current zombie population minus recent human deaths. Quick starvation kills 10% daily, slow starvation kills 1% daily. This can help humans survive longer by reducing the zombie horde naturally.
Can I share my zombie outbreak simulation results?
Yes, all your input parameters are saved in the URL. You can copy the URL from your browser address bar and share it with others to show your exact simulation configuration.