# How to calculate bar width reduction

## How do you calculate the 7 day incidence? (Example)

Using an example for Baden-Württemberg, we will show you how you can calculate the 7-day incidence for your district or your federal state yourself.

If you want to calculate the 7-day incidence for your county or state yourself, you first need the following numbers:

• The new infections in the last 7 days
• The number of inhabitants

You can usually get both values ​​on the homepage of the regional or city district administration or the state government.

### And this is how you calculate the 7-day value

First add up the new infections from the last 7 days and then divide the total by the number of inhabitants in your district or state. Then multiply the result by 100,000.

(New infections / population) x 100,000 = 7-day incidence

The numbers of new infections for Baden-Württemberg can be found in the COVID-19 management report from the State Health Office. Open the documents for the last 7 days. You can find the new infections at the top under "Confirmed cases". This is what the numbers of new infections looked like for the last 7 days on February 24th, 2021 at 4 p.m.

23.02.2021: 892

22.02.2021: 387

21.02.2021: 303

20.02.2021: 858

19.02.2021: 999

18.02.2021: 935

17.02.2021: 913

Total: 5287

As a basis for the number of inhabitants, we refer to the official data for Baden-Württemberg from the State Statistical Office. On November 9th, 2020 this was about 11,102,000 people. This results in the following calculation:

(5287 / 11,102,000) x 100,000 = 47.6

Accordingly, the 7-day incidence on February 24, 2021 was the state average for Baden-Württemberg at 47.6.

### Why are there deviations from the official figures?

The state governments and the Robert Koch Institute (RKI) report the 7-day incidences for the individual federal states and districts on a daily basis. However, if you use the figures from the local health authorities, you will notice that there may be discrepancies between the self-calculated and the official value. On the one hand, this can be due to the fact that there are delays in the reports to the state health authorities and the RKI due to technical hurdles or too high utilization. On the other hand, corrections may be necessary for some figures. In such cases, the values ​​are of course adjusted afterwards. So they are not wrong, but are partly based on different data sets.

Now read on: What is the incidence value of my district?

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