You can add metrics that compare each row of your data to the total value of a column. You can also apply running calculations to the data in your charts.
Add comparison metrics to a chart
 Edit your report.
 Select a chart.

In the Properties panel, select the SETUP tab.
 Choose a metric and click its edit pencil .
 Click the Comparison calculation menu, and select the desired comparison.
 To display the metric's native value, change the Comparison calculation selection to None.
Compare to total
You can compare each row of data to the overall total for that field:
 Percent of total shows the current row's value divided by the column total.
 Difference from total shows the column total minus the current row's value.
 Percent difference from total shows the column total minus the current row's value divided by the column total.
For each of these total comparisons, you can also select Ignore canvas filters in total to compute the total value without applying viewerapplied filters, such as controls. Total rows still include filter properties.
Example
The following table shows the results of applying different "compare to total" options to the Order value field.This lets you evaluate each order's contribution to overall sales.
Item  Quantity sold  Order value  Percent of total  Difference from total  Percent difference from total 

Pretty Bird Bird Seed 
20 
31.96  12.79%  217.85  87.21% 
Healthy Dog Dog Food  16  79.96  32.01%  169.85  67.99% 
Playful Puppy Toy  11  17.97  7.19%  231.84  92.81% 
Parrot Perch  8  74.97  30.01%  174.84  69.99% 
Happy Cat Catnip  4  14.97  5.99%  234.84  94.01% 
Hungry Kitty Cat Food  3  29.98  12%  219.83  88% 
Grand total  62  249.81  100%  0  0% 
Compare to max
You can compare each row of data to the maximum value for that field:
 Percent of max shows the current row's value divided by the maximum value.
 Difference from max shows the current row's value minus the maximum value.
 Percent difference from max shows the current row's value minus the maximum value divided by the maximum value.
Example
The following table shows the results of applying different "compare to max" options to the Order value field. This lets you see how each order compares to the maximum order.
Item  Quantity sold  Order value  Percent of max  Difference from max  Percent difference from max 

Pretty Bird Bird Seed 
20 
31.96  39.97%  48  60.03% 
Healthy Dog Dog Food  16  79.96  100%  0  0% 
Playful Puppy Toy  11  17.97  22.47%  61.99  77.53% 
Parrot Perch  8  74.97  93.76%  4.99  6.24% 
Happy Cat Catnip  4  14.97  18.72%  64.99  81.28% 
Hungry Kitty Cat Food  3  29.98  37.49%  49.98  62.51% 
Relative comparison
When your chart includes a comparison date range, you can apply the comparison function to either the base data or to the corresponding comparison date range.
For example, consider a time series chart that compares the current 28 days to the previous 28 days. The maximum value of Sessions for the current period was 1,947 on June 26. The maximum value of Sessions for the previous period was 1,571 on June 4.
If you apply the Percent of max function relative to base data, then every data point for the previous period will be divided by the maximum value of the current period (1,947). For the data point on June 4, the Percent of max relative to base data would be: 1571/1947 = 80.69%.
If you instead apply the Percent of max function relative to corresponding data, then every data point for the previous period will be divided by the maximum value of the previous period (1,571). For the data point on June 4, the Percent of max relative to corresponding data would be: 1571/1571 = 100%.
Apply running calculations
Running calculations compute summary results across a collection of values. Running calculations return a value for each row of input, expressing that row's relation to the collection as a whole.
The following example shows the application of two running calculations to the Users metric:
 Running sum
 Running delta
Example
Date  Source  Users  Running sum of users  Running delta of users 

May 7, 2018  1,400  1,400  1,400  
May 8, 2018  1,856  3,256  456  
May 9, 2018  1,748  5,004  108  
May 10, 2018  2,046  7,050  298  
May 11, 2018  1,497  8,547  549  
May 12, 2018  1,094  9,641  403 
See a demonstration report here.
Looker Studio supports the following running calculations:
 Running sum
 Running average
 Running min
 Running max
 Running count
 Running delta
 Running percentage delta
To apply a running calculation
 Edit your report.
 Select a chart.

In the Properties panel, select the SETUP tab.
 Add a metric to chart, and then click its edit pencil .
 Click the Running calculation menu, and select the desired function.
 To remove a running calculation, change the Running calculation option to None.
Differences between running calculations and calculated fields
Calculated fields work on the data in your charts on a rowbyrow basis. Running calculations work across rows, making it easy to show complex data relationships without having to code custom SQL queries in your dataset. Such queries would be difficult if not impossible to replicate in a calculated field in your data source.
However, unlike with calculated fields, you can't edit the formulas of running calculations.