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This New Tool Can Help Determine Whether You Should Get Tested for COVID

Man getting tested for COVID.

Ksenia Zvezdina / Getty Images

Key Takeaways

  • The National Institute of Biomedical Imaging and Bioengineering (NIBIB) developed a free online tool to help individuals and organizations decide when to get tested for COVID-19. 
  • To determine COVID-19 risk and transmission, it utilizes a variety of variables including vaccination status, transmission rates based on geographic location, and your safety precautions.
  • 50,000 users around the world are utilizing the When To Test calculator.

As people decide whether to gather with family and friends this holiday season, COVID-19 testing is going to be increasingly important. However, a slew of factors like travel, cold and flu season, and more can make it difficult to determine when you should get tested.

To help alleviate this decision-making burden, the National Institutes of Health Rapid Acceleration of Diagnostics (RADx) initiative developed a COVID-19 tool called the When to Test Calculator.

The calculator is an online and free tool that helps people determine their risk of getting or transmitting COVID-19. To determine your risk, it asks you a variety of questions including your vaccination status, transmission rates in your area, and the safety precautions you're currently taking. 

Users can access the calculator at whentotest.org. After clicking the individual calculator, you'll be prompted to answer the following questions:

  • What state and county are you in? 
  • Are you fully vaccinated
  • Do you wear a mask consistently when you’re indoors with people you don’t live with? 
  • Have you had a COVID test in the last 15 days? 
  • How many people outside your household do you have close contact with on an average day? 
  • Did you attend a social gathering in the last seven days? 
  • Do you plan to attend a social gathering in the next seven days? 


The calculator “is designed to give you an answer on how frequently you should test in order to interrupt the chain of transmission of the virus,” Bruce Tromberg, PhD, director of the National Institute of Biomedical Imaging and Bioengineering (NIBIB) at the National Institutes of Health, told Verywell. 

How the Calculator Works

The calculator was designed through the RADx Tech program, an initiative that launched in April 2020 to accelerate the innovation and development of technologies for COVID-19 testing.

Tromberg says the calculator uses an algorithm that’s been developed and validated throughout the pandemic. It also utilizes data, including data from public health authorities, to determine the prevalence of COVID-19 in specific regions. 

There is also an organizational component to the calculator that allows companies to access testing strategies. Similarly to the individual calculator, the resources requires the user to answer a few questions about:

  • The number of people in the workplace 
  • Vaccination and mask-wearing status
  • Close contact identification 
  • Unmasked workplace size 

After an individual or organization finishes answering the questions, the calculator will display the risk of getting COVID and the risk of transmitting COVID to others in a bar chart format.

“They’re [the results] are color-coded," Tromberg said. "So they go from low to high." The results are provided for informational purposes and should not be interpreted as medical advice, according to the NIH.  

What This Means For You

Whether you are traveling for the holidays or are having difficulty deciding to get tested for COVID-19 after potential exposure, you can get help making your decision at whentotest.org.

Making an Informed Decision

Tromberg said that in the summer, there was a low demand for over-the-counter tests albeit them being available in supermarkets and pharmacies.

“But now, people do want them with the Delta variant,” he added.

One benefit of the COVID calculator is that it was designed to get tests for people who need them the most. The NIH collaborates with the CDC and state public health departments to identify areas where the risk of COVID-19 transmission is high, according to Tromberg. After identifying those areas, they help roll out more tests. 

The tool can not only help people decide whether to get tested, but also identify vulnerable areas where more tests should be available. 

“We collaborate with [public health departments] that say they need help... And a lot of the research that comes from that is an understanding of how people in different parts of the country who may not normally have access to healthcare technologies use this,” Tromberg explained. 

Ultimately, the tool will allow people to make informed decisions about when and how frequently to test, which experts say will help with curbing the spread of the virus.  

So far, over 50,000 people around the world are utilizing the calculator. “It’s a decision assistant tool that we can use in just everyday life,” Tromberg said.

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.

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  1. National Institutes of Health. When to Test offers free online tool to help individuals make informed COVID-19 testing decisions. Updated November 3, 2021.