Year-over-year comparison in Tableau - Step-by-Step Guide

Introduction

Year-over-year comparison helps you see how a number changes from one year to the next. It is useful to understand growth or decline over time, like comparing sales this year to last year.

When you want to compare this year’s sales to last year’s sales to check growth.

When you need to show how website visitors changed from one year to the next.

When your manager asks if profits improved compared to the previous year.

When you want to highlight seasonal trends by comparing the same month in different years.

When you want to track yearly changes in customer counts or product orders.

Steps

Step 1: Open your Tableau workbook

- Tableau Desktop main window

Your data and sheets are visible for analysis

Step 2: Drag the date field to the Columns shelf

- Columns shelf

Dates appear as a timeline across the top of the view

Step 3: Right-click the date field on Columns shelf and select 'Exact Date', then right-click again and choose 'Discrete'

- Columns shelf date field context menu

Dates show as individual years on the axis

Step 4: Drag the measure you want to compare (e.g., Sales) to the Rows shelf

- Rows shelf

A bar or line chart shows the measure values by year

Step 5: Create a calculated field for Year-over-Year change

- Data pane → right-click → Create Calculated Field

A new field window opens to enter the formula

💡 Use the formula: (SUM([Measure]) - LOOKUP(SUM([Measure]), -1)) / LOOKUP(SUM([Measure]), -1)

Step 6: Name the calculated field 'YoY Change' and click OK

- Calculated Field dialog

The new YoY Change field appears in the Data pane

Step 7: Drag the 'YoY Change' field to the Rows shelf next to your measure or to the Tooltip shelf

- Rows shelf or Tooltip shelf

The view updates to show year-over-year change values or shows them when hovering over data points

Before vs After

Before

The chart shows total sales for each year: 2019 = 100,000; 2020 = 110,000; 2021 = 105,000

After

The chart shows total sales and year-over-year change: 2020 = +10%, 2021 = -4.5%

Settings Reference

Date field type

📍 Columns shelf → right-click date field

Controls how dates are grouped and displayed for comparison

Default: Year (Discrete)

Calculation formula

📍 Calculated Field dialog

Defines how year-over-year change is calculated

Default: None

Measure aggregation

📍 Rows shelf → measure field

Determines how data values are summarized for each year

Default: SUM

Common Mistakes

Using continuous date instead of discrete year

Continuous dates show a timeline that can confuse year-over-year comparisons

Use discrete year to clearly separate each year on the axis

Not using LOOKUP function in the calculation

Without LOOKUP, the calculation cannot compare current year to previous year

Use LOOKUP(SUM([Measure]), -1) to get the previous year's value

Placing the YoY calculation on the wrong shelf

If placed incorrectly, the calculation may not display or update properly

Place the YoY Change field on Rows shelf or Tooltip shelf for correct visualization

Summary

Year-over-year comparison shows how a measure changes from one year to the next.

Use discrete year dates and a calculated field with LOOKUP to create the comparison.

Place the YoY calculation on the view to see percentage changes clearly.