Power BI vs Excel: When to Use Which, Honestly

Power BI versus Excel is the wrong framing. Both tools are going to be in your business for a long time to come, and pretending otherwise ends up costing you either time or money or both. The interesting question is not which tool wins. It is which tool is right for which job, and how to run the two together without doubling every piece of work.

Where Excel still wins

Excel is still the fastest way to do a handful of things. Genuine one off analysis where the shape of the question is not known in advance. Structured modelling that changes on every iteration, like a merger valuation or a budgeting exercise. Anything a small group of people are going to collaborate on in real time. And, in most UK finance teams, the actual statutory reporting that has to tie back to the letter of the accounts.

Excel is also better than Power BI at freeform layout. If the end result has to look like an invoice, a schedule or a specific board pack template, Excel wins because you can put anything anywhere.

Where Power BI wins

Power BI wins the moment the same report has to be produced more than three times. It also wins when several people need to see the same numbers refreshed on a schedule, when different users need to see different subsets of the data, when the source data lives in more than one system, and when the report needs to be trusted by people who did not build it.

Power BI also wins on scale. A well built Power BI report renders instantly on a hundred million rows of data. Excel starts to slow down at half a million and gives up at a million.

The tests we use in a first client meeting

On a first Power BI consultancy call we tend to run through the same short set of tests. If the answer to most of them is yes, Power BI is the better home for that piece of reporting.

• Does more than one person need to see this?
• Is it produced more often than once?
• Does the source data live in a system, not in a file?
• Would it be a problem if two different people opened it and got different numbers?
• Do different users need to see different rows?
• Would it be useful to have this on a phone or a shared screen?

If the answer to most is no, Excel is probably still the right home. If the answer to most is yes, the report belongs in Power BI, and continuing to build it in Excel is just future cost.

How to run the two together

The best pattern in most UK businesses is a clear division of labour. Power BI holds the recurring, trusted reporting layer. Excel is used for one off analysis, statutory reporting and modelling. And, critically, Excel can connect live to a Power BI dataset when a user wants to do their own analysis against the trusted numbers. That last capability is under used. It lets analysts work in the tool they know best without breaking the single version of truth.

The wrong pattern is Excel and Power BI both hitting the same source system independently, producing their own definitions of the same metric. That is how the same revenue number ends up looking different in two reports.

Common anti patterns we see

• Building a Power BI report to look exactly like an existing Excel workbook, complete with merged cells and colour coded rows. If it has to look like a spreadsheet, keep it as one.
• Exporting from Power BI to Excel to do the actual analysis. Fine occasionally, but if it is happening every week the Power BI report is not doing its job.
• A finance team maintaining a huge Excel model that everyone quietly ignores in favour of the Power BI version, or vice versa.
• Power BI reports that are recreated in Excel every month for the board pack because the board pack template is Excel. Publish paginated reports or use PowerPoint integration instead.

What we usually recommend

For most UK businesses arriving at us, the practical answer is to keep Excel as the flexible personal analysis and modelling tool, and move all recurring reporting into Power BI. The migration is not really about the tools. It is about picking a canonical model, defining the metrics once and getting the reporting on top of that model. The tools do what they are good at.

If you would like a hand deciding what to move and what to leave, our Power BI audit page covers how we approach the review, and Power BI consultancy covers the wider build and support work.

Frequently asked questions