Power BI vs Excel for Data Analysts: A Practical Comparison

let
    Source = Folder.Files("C:\\Reports\\Monthly"),
    CsvOnly = Table.SelectRows(Source, each Text.EndsWith([Name], ".csv")),
    Parsed = Table.AddColumn(CsvOnly, "Data",
        each Table.PromoteHeaders(Csv.Document([Content]))),
    Combined = Table.Combine(Parsed[Data]),
    Typed = Table.TransformColumnTypes(Combined,
        {{"OrderDate", type date}, {"Amount", type number}}),
    Trimmed = Table.TransformColumns(Typed, {{"City", Text.Trim}}),
    Deduped = Table.Distinct(Trimmed, {"OrderID"})
in
    Deduped

Clean a name column:
=PROPER(TRIM(A2))

Convert text dates like 05/11/2026 (dd/mm/yyyy) to real dates:
=DATE(RIGHT(B2,4), MID(B2,4,2), LEFT(B2,2))

Flag duplicates in an OrderID column:
=IF(COUNTIF($C$2:$C$5000, C2) > 1, "Duplicate", "")

Use these for quick, one-off fixes; use Power Query
for anything you will repeat.

Total revenue for the selected month in cell F1:
=SUMIFS(Sales[Revenue], Sales[Month], F1)

Same month last year:
=SUMIFS(Sales[Revenue], Sales[Month], EDATE(F1, -12))

Growth %:
=IFERROR((F2 - F3) / F3, "")

Average order value:
=F2 / COUNTIFS(Sales[Month], F1)

Total Revenue = SUM ( Sales[Revenue] )

Revenue LY =
CALCULATE ( [Total Revenue], SAMEPERIODLASTYEAR ( 'Date'[Date] ) )

Revenue Growth % =
DIVIDE ( [Total Revenue] - [Revenue LY], [Revenue LY] )

Avg Order Value =
DIVIDE ( [Total Revenue], DISTINCTCOUNT ( Sales[OrderID] ) )

-- Each measure works in every visual and responds to all filters.

Excel one-page dashboard

Top row:   KPI cells (Revenue, Orders, Avg Order Value) linked to pivots
Middle:    Pivot line chart - revenue by month
Bottom:    Pivot bar chart - revenue by region | Top 5 products table
Right:     Slicers (Region, Category) connected to all pivots

Keep raw data and pivots on separate sheets.
Share as a file or through a shared drive.

Power BI report page

Visuals:
  Cards: Total Revenue, Revenue Growth %, Avg Order Value
  Line: Total Revenue by Date[Month]
  Bar: Total Revenue by Region (click to cross-filter)
  Table: Top 5 products by Total Revenue
Filters: Category slicer, Date range slicer
Drill-through: Region details page

Publish to a workspace; schedule refresh after data loads;
share via an app with role-based access.

Question                                      Use
One-off question, small data?                 Excel
Detailed calculation or what-if model?        Excel
Same report every week for many people?       Power BI
Many related tables, period comparisons?      Power BI
Need access control by role or region?        Power BI
Cleaning steps you will repeat?               Power Query (either)

Weeks 1-2  Excel: tables, XLOOKUP, SUMIFS, pivots
Week 3     Power Query in Excel: clean and combine files
Week 4     Power BI: import, relationships, star schema
Week 5     DAX: basic measures, CALCULATE, time intelligence
Week 6     Power BI report design, publishing, refresh
Week 7     Rebuild one Excel report in Power BI and compare

Project: Same sales question, two tools

1. Excel: Power Query cleaning, pivots, one-page dashboard
2. Power BI: same data, star schema, DAX measures, report page
3. README: what was faster, clearer and easier to share in each

Shows both skills and good tool judgement.