Nobody knows, and no experiment has shown it either way; what philosopher Nick Bostrom argued in 2003 is narrower: at least one of three things must be true, either almost no civilisation reaches the technology to simulate minds, or almost none that do choose to, or we are almost certainly simulated. Set your own assumptions below and see which option they point to. It's a thought experiment, not a measurement.
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The tool uses the formula from Bostrom's paper, "Are You Living in a Computer Simulation?" (Philosophical Quarterly, 2003):
The paper assumes each simulation holds about as many people as the real history before the posthuman stage, which is why that number cancels out. Because NI could be enormous, fsim rushes towards 100% unless A or B is tiny. That's the whole trilemma: something has to give. The tool reports which option your settings lean on; it can't tell you which settings are true, and nobody currently can.
This tool puts a few of the named techniques from We Are in a Simulation to work. Each line says how it relates to the tool.
See every technique in We Are in a Simulation →
Nobody knows. There is no accepted evidence either way, and many physicists say the idea isn't currently testable. Bostrom's argument doesn't claim we are simulated; it claims at least one of three options is true: civilisations almost never reach that technology, or almost never choose to run such simulations, or we are almost certainly in one.
If advanced civilisations ran many detailed simulations of their ancestors, simulated minds would vastly outnumber original ones, so a mind like yours should bet it is simulated. The only ways out are that such civilisations are very rare or that they almost never run those simulations.
No. Some features of physics resemble computation (quantities come in discrete units, information seems fundamental), but they are equally consistent with an ordinary universe. Physicists have proposed tests, such as looking for lattice-like effects in very high-energy cosmic rays (Beane, Davoudi and Savage, 2014), but nothing has detected a simulation.
That consciousness may not be possible on a computer (the argument assumes it is), that we can't assign meaningful probabilities to the first two options, and debates about the "bland indifference" step from fractions of observers to your own credence. Bostrom and Kulczycki published a technical correction to the argument in 2011.
Practically, very little: you would still get hungry, rent would still be due and actions would still have consequences by the same rules. The philosopher David Chalmers argues that even a simulated world would be real for those living in it.
A philosophy thought experiment, clearly labelled as one; not a scientific measurement or a claim about reality. If you ever feel that the world or your own body isn't real in a way that frightens you, that's a recognised and treatable experience (derealisation or depersonalisation): please talk to a doctor.