Speed Up Report Development With Custom Power BI Themes

by Roger Light, Data & Analytics Consultant, Altis Consulting UK

Ever spend time fiddling with obscure settings in your reporting tool to get things to look consistent? Sometimes the data modelling and visualisation layout are a breeze compared with ironing out those small distracting details to make your report look good. So why bother? Because those distracting details prevent us from taking in the report’s message.

Whether it’s a carefully curated presentation telling the story of pre-identified trends, or an indicator tracking report designed to surface key numbers for quick assimilation and response, mismatched fonts, colours, axis formatting or line widths stick out and command our attention, even if only momentarily, and create a barrier to communication.

Not only that, but for some in your report audience, such inconsistencies imply carelessness, and this can even undermine the credibility of the data in your report, even if such an association is entirely spurious. So, anything that can help to remove distractions, and save us hours of clicking in settings menus, is going to be helpful. For Power BI, this is where Themes come in.

What can themes do for you?
  • Save time and clicks. Themes can immediately apply a whole host of report and visualisation settings that could otherwise take you a long time to set up.
  • Standardise your reports. Once saved in a theme, your preferred settings can be applied to every new report you create, giving all your reports a familiar look and feel. They can even help provide that consistency across multiple report authors.
  • Branding implementation. You can use themes to implement elements, especially colour, from your organisation’s brand guidelines. And if in the future, your organisation goes through a rebrand and suddenly all your reports look old and dated, you can update the theme and then use it to bring each of your reports back on brand with just a few clicks.


What can’t themes do for you?
  • Show you what looks good. It’s possible to have a theme that will make all your reports equally unreadable! Themes are a powerful tool that needs to be wielded with care. They will accelerate the implementation of your data visualisation knowledge but that still requires you to know how to make good use of data-ink, colours and alternative indicators such as icons. Altis offers Data Visualisation Best Practices training to help you communicate more effectively with data.
  • Enforce rules. Themes only alter the default settings for visuals on your reports. It is still possible to change any of these settings manually to whatever you want them to be. This flexibility is important because even the most carefully thought out theme will not accommodate all the requirements you might have; there will be times when there is a very good reason to depart from the theme. But this also means that you can’t use themes to enforce brand or other visual guidelines; this will always be down to execution by the report author.


How much difference do themes really make?

Look at the report below, which uses sales data from one of Microsoft’s fictitious sample databases:

This report is typical in the information that it is trying to impart. On the left, we have a few key numbers and a breakdown of monthly profit in a table. Then we have a series of tables, matrices and line graphs drilling into product categories and showing trends over the last 12 months.  This report was created using Power BI’s default theme and very few of those default settings have been changed.

To be fair, it could look worse. But we are trying to fit a lot of information into the report and so it’s critical that we don’t have too much clutter. In the case of our tables and matrices, despite careful arrangement, we must either have scrollbars or else no gap at all between the visuals. Neither is good for readability, but the scroll bars appear to be the lesser offence. Meanwhile, at first glance, the year on year profit and monthly trend lines are competing for our attention, so that we barely notice the other big numbers or indeed the report month date over on the top right, which gives the whole report its context.

Can we create a theme under which this report will look better, without having to make lots of manual changes to settings? The report below has been changed from the one above by selecting a custom Power BI Theme with a few mouse clicks.

This immediately looks much cleaner. We have smaller font, still perfectly readable on the full-sized report, which means we no longer have to choose between scrollbars or over-crowded visuals. We have also set a grey background, which allows us to indicate different areas on our report to improve readability further. All our key numbers are now highlighted in an eye-catching colour, not just the bad news! And this includes our crucial report month date over on the top right. The line graph colours on the other hand have been demoted to more neutral greys, again they are perfectly readable but now they don’t jump out at us so much.

Another place where we have colour is the conditional formatting in the Category Contribution and Declining Products visuals. In the first version of the report, these shades are not helpful. The most highlighted data is not always what we are interested in, while numbers at the other extreme are impossible to read as their shade is too light. In the second version, our theme has defaulted to the same colours we have for our key numbers, blue being good and red being bad. All the numbers are readable and it’s obvious where the poor performance lies.

We could of course achieve these same changes without using a theme, making each setting alteration manually. But consider the amount of effort involved. If this is the only Power BI report we ever create, we may as well do it manually. But in the real world where we have another report to do straight after this one, and another three reports due next week, this theme soon returns the investment of time required to create it.


How to Create a Power BI Theme

It is straightforward to make simple changes to Power BI themes. On the View ribbon in Power BI Desktop, along with a selection of standard themes to choose from, are some other options for working with themes, highlighted in the illustration below.

We can browse the Theme gallery on the web and download custom themes created by other users. We can choose to Customize current theme to make alterations to an existing theme and then Save current theme to export it to a JSON file. Finally, we can use Browse for themes to import a custom theme file.  This theme customisation allows for some straightforward high-level colour and font changes and is worth checking out.

There is a problem though, the customisation available here provides only limited control over your reports. What works for a key performance indicator or column chart visual may look dreadful for a table or a matrix. The How to create a theme link opens this article to get you started with editing the JSON files manually, giving much finer control, specific to each type of visual. And if writing JSON isn’t your thing you can of course get Altis to help you.


With the appropriate application of data visualisation best practice, custom Power BI themes can bring a significant improvement to the look and feel of your reports, and save hours of report editing time. They can also bring standardisation and flexibility in the face of changing brand guidelines.

It is easy to make simple changes to themes but for more comprehensive functionality like that on display above, you will need to learn some JSON or may want some assistance from us.

Connect with us if you’d like to learn more about how we can help you be successful with Power BI.

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