Assumption mapping

Introduction

What is it?

When building products, we make countless assumptions about our users, the market, and what’s technically possible. Some of these assumptions are spot on, but others? Not so much. And if we get them wrong, it can be costly.
That’s where Assumption Mapping comes in. It is a structured approach to uncovering and assessing the beliefs that shape product decisions. These assumptions typically fall into three categories:

Desirability: Are we sure users want this?
These are assumptions about user needs, behaviours, and preferences.
Examples:
“Our employees would love a share or comment button on the intranet.”
“Customers are probably frustrated that this device lacks voice control.”
Viability: Does this make business sense?
These assumptions relate to market demand and business value.
Examples:
“Offering a digital version of our training makes sense because online courses are booming.”
“Users will pay €9.99/month for our premium subscription.”
Feasibility: Can we build this?
These are assumptions about technical capabilities and constraints.
Examples:
“Our AI chatbot can handle 90% of user inquiries without human help.”
“Integrating third-party APIs will be seamless and won’t slow down performance.”

Why do it?

Assumptions can either fuel great ideas or lead to costly mistakes. Assumption Mapping helps teams:

Reduce risk: Spot potential pitfalls early.
Make smarter decisions: Prioritise which assumptions need validation.
Align teams: Get everyone on the same page about uncertainties.
Stay user-focused: Test what truly impacts user experience.
Save time and money: Validate critical assumptions before full-scale execution.

Step by Step Guide

1. Gather Stakeholders 2. Identify Your Assumptions 3. Prioritize Assumptions 4. Validate High-Risk Assumptions

STEP 01

Gather Stakeholders

Involve people with different perspectives— UX designers, product managers, developers, marketers. A diverse team leads to richer insights.

Make sure to be aligned on what problem you will be focusing on.

Step 02

Identify Your Assumptions

Run a workshop to brainstorm assumptions.
Categorize them under User Behavior, Market Trends, Technical Feasibility, Business Viability, or any category relevant to your project.
Give each person sticky notes and have them write down one assumption per note.
Encourage quantity—capture as many as possible!
End with a round of: “What else do we still need to know?”

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Assumption Mapping Template

This template will assist you in organizing your assumption mapping workshop. It focuses on three groups of assumptions: desirability, viability, and feasibility. A fourth column is included for any additional ideas that may arise.

Step 03

Prioritize Assumptions

Plot assumptions on a matrix based on:

Certainty (Known vs. Unknown) – Do we have data to back this up?
Risk (High vs. Low Impact) – What happens if we’re wrong?

Where to focus:

High risk & unknown → Test first (Critical assumptions that could make or break the product.)
High risk & known → Monitor closely (You have some data but keep an eye on it.)
Low risk & unknown → Test later (Not urgent, but worth exploring.)
Low risk & known → No immediate action needed (Safe bets.)

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