If you’re about to head into a cramped basement bar in a city where the vaccination rate is low and the COVID-19 case rate is high, it’s easy to deem the situation risky. But the risk factor for every outing isn’t quite so clear—and even for obviously high-risk ones, it’s not obvious what your actual chances of catching the virus are.

The makers of the microCOVID Project are hoping to help. As Smithsonian reports, the microCOVID Project is essentially a website that pulls together pertinent data—vaccine efficacy, transmission and vaccination rates by region, case counts, etc.—and quantifies the risk for pretty much any given activity, which you can customize to fit your circumstances. After entering your location, you can either choose a scenario from the dropdown menu or start building your own from scratch. (If you choose a preexisting one, you can still tweak all the details.)

Say, for example, you’re in Kings County, New York; you’ve received two doses of the Moderna vaccine; and you want to know how risky it would be to eat outside at a restaurant. Enter that information, and then update the other boxes with whatever other details you know: how long you’ll be there, how many people will be within 15 feet of you, whether you’ll be wearing a mask (and what type of mask), and so on. As you progress through the form, the risk counter at the bottom of the screen will tell you a risk level from low to high.

The counter will also tell you what percentage of your “weekly risk budget” the outing will use up and roughly how many “microCOVIDs” it accounts for. One microCOVID—a unit of measurement that the project’s creators came up with—equals a single one-in-a-million chance of contracting COVID-19. So if your outdoor dining experience amounts to approximately 67 microCOVIDs, your chances of getting infected during it are 67 in 1 million. You can adjust the weekly risk budget based on what you’re comfortable with, but its default is 200 microCOVIDs per week, which works out to about 10,000 microCOVIDs per year. With that budget, your overall chance of contracting COVID-19 over a year is about 1 percent.

As Yale University epidemiologist F. Perry Wilson told Smithsonian, the tool could potentially give people “a false sense of security” about the safety of their activities. In other words, you might unintentionally start letting the weekly budget counter overtake your own good decision-making skills.

But the microCOVID Project can help you compare risk levels of two completely different situations—e.g. a plane ride where everyone’s masked and a crowded outdoor party where everyone’s unmasked—and make decisions about what (and how much) stuff you’re willing to do.

You can try it out for yourself here.

[h/t Smithsonian]