Ratios for COVID-19

Recently, several people have questioned my formula.
I stand by my numbers.

Here are the base numbers:

The most recent official population of Salem is 29,791.
https://www.census.gov/quickfacts/fact/table/salemtownrockinghamcountynewhampshire/AGE295219

The most recent cumulative total of Salem residents (Nov. 22) is 621.
https://www.nh.gov/covid19/index.htm


Here are the formulas:

  • To get the ratio: (Population / Cases)
  • To get the number of cases to reach the ratio: (Population/Ratio)
  • To get the percentage: ((Cases / Population) x 100)
Current ratio:

29,791 / 621 = 47.97, rounded to 48.

Current percentage:

621 / 29,791 =  2.08%, rounded to 2.1%.

So we can say one out of every 48 Salem Residents have had COVID-19.
We can also say it’s 1:48 or 2.1%.


Some people seem to be afraid that we are rapidly reaching one out of five or even one out of one. We are a very long way away from that, and I doubt we will ever reach any where near that level. Hopefully, I am right.


The lower the ratio goes, a bigger increase in cases is needed to move the needle to the next number. Like this:

  • 1:50 is 596 Salem residents with infections. (population/ratio)
  • 1:10 is 2,979, five times as many cases as 1:50.
  • 1:5 is 5,958 people, twice as many cases as 1:10.
  • 1:2 is 14,896 people, five times as many cases as 1:10.
  • 1:1 is 29,791 people, everyone in Salem and twice as many as 1:2.

I don’t see us getting anywhere near that that high. 


This chart shows the highest Salem numbers can go.
Obviously, it can’t get below 1:1, or above 100%!

PopulationRatio 1:xCasesIncrease in casesPercentage
29,791100.029831.00%
29,79199.030131.01%
29,79198.030431.02%
29,79197.030731.03%
29,79196.031031.04%
29,79195.031431.05%
29,79194.031731.06%
29,79193.032031.08%
29,79192.032431.09%
29,79191.032741.10%
29,79190.033141.11%
29,79189.033541.12%
29,79188.033941.14%
29,79187.034241.15%
29,79186.034641.16%
29,79185.035041.18%
29,79184.035541.19%
29,79183.035941.20%
29,79182.036341.22%
29,79181.036841.23%
29,79180.037251.25%
29,79179.037751.27%
29,79178.038251.28%
29,79177.038751.30%
29,79176.039251.32%
29,79175.039751.33%
29,79174.040351.35%
29,79173.040861.37%
29,79172.041461.39%
29,79171.042061.41%
29,79170.042661.43%
29,79169.043261.45%
29,79168.043861.47%
29,79167.044571.49%
29,79166.045171.52%
29,79165.045871.54%
29,79164.046571.56%
29,79163.047371.59%
29,79162.048181.61%
29,79161.048881.64%
29,79160.049781.67%
29,79159.050581.69%
29,79158.051491.72%
29,79157.052391.75%
29,79156.053291.79%
29,79155.0542101.82%
29,79154.0552101.85%
29,79153.0562101.89%
29,79152.0573111.92%
29,79151.0584111.96%
29,79150.0596122.00%
29,79149.0608122.04%
29,79148.0621132.08%
29,79147.0634132.13%
29,79146.0648142.17%
29,79145.0662142.22%
29,79144.0677152.27%
29,79143.0693162.33%
29,79142.0709162.38%
29,79141.0727172.44%
29,79140.0745182.50%
29,79139.0764192.56%
29,79138.0784202.63%
29,79137.0805212.70%
29,79136.0828222.78%
29,79135.0851242.86%
29,79134.0876252.94%
29,79133.0903273.03%
29,79132.0931283.13%
29,79131.0961303.23%
29,79130.0993323.33%
29,79129.01,027343.45%
29,79128.01,064373.57%
29,79127.01,103393.70%
29,79126.01,146423.85%
29,79125.01,192464.00%
29,79124.01,241504.17%
29,79123.01,295544.35%
29,79122.01,354594.55%
29,79121.01,419644.76%
29,79120.01,490715.00%
29,79119.01,568785.26%
29,79118.01,655875.56%
29,79117.01,752975.88%
29,79116.01,8621106.25%
29,79115.01,9861246.67%
29,79114.02,1281427.14%
29,79113.02,2921647.69%
29,79112.02,4831918.33%
29,79111.02,7082269.09%
29,79110.02,97927110.00%
29,7919.03,31033111.11%
29,7918.03,72441412.50%
29,7917.04,25653214.29%
29,7916.04,96570916.67%
29,7915.05,95899320.00%
29,7914.07,4471,49025.00%
29,7913.09,9302,48333.33%
29,7912.014,8954,96550.00%
29,7911.029,79114,896100.00%

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