Rolling period calculations in Tableau - Cell-by-Cell Formula Trace

Sample Data

Daily sales data for five consecutive days in January 2024.

Cell	Value
A1	Date
B1	Sales
A2	2024-01-01
B2	100
A3	2024-01-02
B3	150
A4	2024-01-03
B4	200
A5	2024-01-04
B5	130
A6	2024-01-05
B6	170

Formula Trace

WINDOW_SUM(SUM([Sales]), -2, 0)

Step 1: SUM([Sales]) at 2024-01-01

Step 2: WINDOW_SUM(SUM([Sales]), -2, 0) at 2024-01-01

Step 3: SUM([Sales]) at 2024-01-02

Step 4: WINDOW_SUM(SUM([Sales]), -2, 0) at 2024-01-02

Step 5: SUM([Sales]) at 2024-01-03

Step 6: WINDOW_SUM(SUM([Sales]), -2, 0) at 2024-01-03

Step 7: SUM([Sales]) at 2024-01-04

Step 8: WINDOW_SUM(SUM([Sales]), -2, 0) at 2024-01-04

Step 9: SUM([Sales]) at 2024-01-05

Step 10: WINDOW_SUM(SUM([Sales]), -2, 0) at 2024-01-05

Cell Reference Map

Sales

↓

Sales

↓

Sales

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Sales

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Sales

The formula uses sales values from the current and previous two dates to calculate the rolling sum.

Result

     A          B          C
1  Date       Sales    Rolling Sum
2  2024-01-01  100         100
3  2024-01-02  150         250
4  2024-01-03  200         450
5  2024-01-04  130         480
6  2024-01-05  170         500

Column C shows the rolling sum of sales for the current day and the two previous days.

Sheet Trace Quiz - 3 Questions

What is the rolling sum value on 2024-01-03?

A 450

B 200

C 350

D 300

Key Result

WINDOW_SUM(SUM([Measure]), -N, 0) calculates a rolling sum over the current and previous N rows.