What a 312% ROI figure is made of

Slack commissioned Forrester Consulting to measure what enterprises gain by running their work through Slack. The headline is 312% ROI over three years. The Total Economic Impact of Slack

Here is how that number was built. Forrester interviewed six decision-makers at companies in SaaS, fintech, media, transportation and technology. It then modelled a composite organization with 25,000 employees and $10 billion in revenue. The ROI belongs to that composite. No single company reported it.

Every TEI works this way, including Bugcrowd's study of its managed bug bounty Forrester TEI Report, and it isn't a trick. Composites protect the people interviewed and smooth out outliers. Still, six interviews is a small base, and the vendor usually helps choose who gets interviewed.

How to use one anyway

• Ignore the ROI. Find the benefit categories and the assumption behind each.
• Swap in your own headcount and salaries. Most TEIs publish enough of the model to let you.
• Check which costs were counted. Migration, training and the months of running two tools side by side are where costs usually hide.

Slack pairs the study with a comparison guide against Microsoft Teams and a migration playbook built on three phases: prepare, maintain, transform. For an IT lead deciding whether to switch, those two are more useful than the ROI.