Purpose: Task Completion Rate is a quantitative usability metric that measures how effectively users complete a designed task, helping teams understand real-world usability bottlenecks.
Design Thinking Phase: Test
Time: 45–60 min session + 1–2 hours analysis
Difficulty: ⭐⭐
When to use:Validating a design pre-launch with real usersTesting a new user flow for task efficiencyComparing two design variations using benchmark metrics
What it is
Task Completion Rate is a quantitative usability metric used in UX testing to measure the percentage of users who successfully complete a given task. It's a foundational way to evaluate whether a digital product is easy to use and whether key interactions are intuitive.
📺 Video by NNgroup. Embedded for educational reference.
Why it matters
Task Completion Rate gives designers and product teams a clear signal about real usability. While qualitative insights explore the "why" behind behaviours, Task Completion Rate reveals “if” users were able to complete essential tasks—and how consistently. It’s often a go-to metric for comparing iterations, tracking UX improvements over time, and aligning stakeholders around measurable outcomes.
When to use
- In usability tests during the prototyping or validation phase
- When refining complex user flows like onboarding or checkout
- To quantitatively benchmark a redesigned product or journey
Benefits
- Rich Insights: Helps uncover user needs that aren’t visible in metrics.
- Flexibility: Works across various project types and timelines.
- User Empathy: Deepens understanding of behaviours and motivations.
How to use it
- Choose specific tasks representative of real user goals (e.g., “Transfer funds,” “Book an appointment”).
- Test with a minimum of 5–10 users matching your personas.
- Clearly define success criteria for each task (e.g., “User reaches confirmation page without assistance”).
- Run moderated or unmoderated sessions using usability platforms or live tests.
- For each task, mark whether the user succeeded, gave up, or needed help.
- Calculate the Task Completion Rate:
Task Completion Rate (%) = (Number of users who completed the task / Total users) × 100 - Analyse drop-off patterns and clusters of failure to guide design improvements.
Example Output
During a usability test of the mobile check-in process for a fictional healthcare app, 10 users attempted the same 3-step check-in task:
- Task: Check in for an upcoming appointment via the app
- Success Criteria: Reaches final screen confirming completion
Results:
- 8 out of 10 completed successfully without help
- 1 needed assistance at the document upload step
- 1 gave up at the second screen due to unclear interaction
Task Completion Rate: 80%
Common Pitfalls
- Vague task definitions: Results are unreliable if users don’t understand what’s expected.
- Confusing success criteria: Be explicit—is success reaching a page, performing an action, or avoiding errors?
- Small or biased samples: Avoid overinterpreting results with too few participants or unrepresentative users.
- Overreliance on numbers: Always pair quantitative metrics with observed behaviours.
10 Design-Ready AI Prompts for Task Completion Rate – UX/UI Edition
How These Prompts Work (C.S.I.R. Framework)
Each of the templates below follows the C.S.I.R. method — a proven structure for writing clear, effective prompts that get better results from ChatGPT, Claude, Copilot, or any other LLM.
C.S.I.R. stands for:
- Context: Who you are and the UX situation you're working in
- Specific Info: Key design inputs, tasks, or constraints the AI should consider
- Intent: What you want the AI to help you achieve
- Response Format: The structure or format you want the AI to return (e.g. checklist, table, journey map)
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Prompt Template 1: “Analyse Drop-Off Points in a User Flow”
Analyse Drop-Off Points in a User Flow
Context: You are a UX researcher reviewing usability test data for a [check-in process] in a [healthcare app].
Specific Info: The Task Completion Rate is [73%], with completion failures at the [document upload] step. User personas include [older adults aged 60–75].
Intent: Identify UX issues leading to task failure, and suggest what should be tested next.
Response Format: Provide a summary of likely friction points, severity level, possible root causes, and 1 top design fix to test.
Ask clarifying questions if steps or personas are unclear.
Suggest one follow-up research activity.
Prompt Template 2: “Design a Task Clarity Checklist for Usability Tests”
Design a Task Clarity Checklist for Usability Tests
Context: You’re preparing a moderated usability test to measure Task Completion Rate for a [multi-page checkout flow] in an [eCommerce app].
Specific Info: Tasks involve product selection, payment method input, and confirmation.
Intent: Ensure each task prompt is clear, has defined success criteria, and avoids biasing participants.
Response Format: Return a bullet-point checklist to review task clarity and test neutrality.
If the flow includes system feedback or edge cases, indicate how that should be controlled for.
Suggest 1 warm-up question to establish user context.
Prompt Template 3: “Summarise Design Weaknesses That Impact Task Success”
Summarise Design Weaknesses That Impact Task Success
Context: You are a UX lead reviewing session data from unmoderated usability tests.
Specific Info: Participants failed tasks involving navigation menus and icon use in a [web-based admin dashboard].
Intent: Identify design elements most responsible for drop-off and prioritise them for iteration.
Response Format: List top 3 UI elements with their probable usability faults and severity ranking.
Recommend next step: prototype fix or further testing?
Prompt Template 4: “Benchmark Two Flows Using Task Completion Rate”
Benchmark Two Flows Using Task Completion Rate
Context: You’ve run A/B tests comparing two designs for a [subscription payment flow].
Specific Info: Version A scored 65% Task Completion; Version B scored 85%. Sample size = 20 users.
Intent: Analyse what design changes led to higher task success.
Response Format: Comparative analysis table with flow changes, hypotheses, and effect size on success.
Consider interface affordances, microcopy, error prevention.
Suggest one hypothesis to A/B test next.
Prompt Template 5: “Generate Tasks for Measuring Completion in Onboarding”
Generate Tasks for Measuring Completion in Onboarding
Context: You are testing a new onboarding process in a [productivity app].
Specific Info: Flows include profile setup, notification preferences, and first task creation.
Intent: Create tasks that emulate realistic user goals and provide measurable task outcomes.
Response Format: List task scripts + their success criteria.
Flag any steps that may require moderation/user guidance.
Prompt Template 6: “Recommend Tools for Task Completion Testing”
Recommend Tools for Task Completion Testing
Context: You're leading a lean UX team at a startup with limited budget and internal research ops.
Specific Info: You need to run both moderated and unmoderated usability tests focusing on task completion.
Intent: Identify 3 affordable platforms or tools suited to test flows on web and mobile.
Response Format: Table with tools, cost estimate, and best use case.
Optionally suggest how to combine these into a hybrid workflow.
Prompt Template 7: “Structure a Research Playback Using Task Completion Metrics”
Structure a Research Playback Using Task Completion Metrics
Context: You’re preparing a stakeholder presentation on recent UX testing.
Specific Info: 4 core user flows tested; Task Completion ranged from 58% to 92%.
Intent: Frame insights using narrative and data to show where the experience succeeds and fails.
Response Format: Create a slide outline with intro, summary table, insights per flow, and next steps.
Suggest 1 compelling visual to support the story.
Prompt Template 8: “Evaluate Task Success Criteria Clarity”
Evaluate Task Success Criteria Clarity
Context: You’re defining tasks for a remote usability test covering a [mobile navigation redesign].
Specific Info: Tasks may involve gestures, filtered search, and multiple success paths.
Intent: Review if success criteria are objectively measurable and aligned with real user goals.
Response Format: Table of task → success criteria → potential ambiguity notes.
Ask me to clarify if tasks are vague or overlapping.
Prompt Template 9: “Draft Recommendations for Low Performing Task Segments”
Draft Recommendations for Low Performing Task Segments
Context: Analysis shows a Task Completion Rate below 70% for account linking in a [banking app].
Specific Info: Users drop off at the third step involving multi-factor authentication.
Intent: Highlight design or content fixes to improve flow completion.
Response Format: Recommend 3 improvements with rationale and expected impact.
Suggest a quick validation method.
Prompt Template 10: “Create a Facilitator Script Focused on Task Success”
Create a Facilitator Script Focused on Task Success
Context: You’re conducting moderated usability tests aimed at measuring completion and uncovering friction.
Specific Info: 5 tasks in scope, including critical business actions.
Intent: Deliver consistent facilitation while allowing natural user behaviour.
Response Format: Script with task introductions, neutral prompts, follow-up probes.
Add briefing and closing statements.
Recommended Tools
- Maze: Ideal for unmoderated usability tests with built-in metrics like Task Success and Misclick Rate.
- PlaybookUX: Supports quantitative analysis alongside video recordings in moderated sessions.
- Lookback.io: Used for moderated sessions; great for tagging user moments during success/failure states.
- Hotjar: While not a testing tool, its funnel and behaviour analytics help correlate task failure with UX friction.
