What is a Logic Model?
A clear definition of logic model for charities — how it maps inputs, activities, outputs, outcomes, and impact in a visual framework, how it differs from a theory of change, and when funders require one.
TL;DR: A logic model is a one-page visual diagram showing how a charity programme works — tracing the cause-and-effect chain from inputs and activities through to outputs, outcomes, and impact. It is simpler and more linear than a theory of change, making it a practical tool for programme planning and grant applications. Most major UK funders, including the National Lottery Community Fund, expect applicants to demonstrate clear programme logic. For full step-by-step guidance, see the Logic Model for Charities: The Complete Guide.
The Short Definition
A logic model is a concise, usually one-page diagram that maps the intended cause-and-effect relationships within a programme. It answers a straightforward question: if we invest these resources and deliver these activities, what results do we expect?
The framework was popularised in UK grant-making through the Big Lottery Fund — now the National Lottery Community Fund — which included logic model templates in its evaluation guidance from 2010 onwards. Today, the tool is standard practice across the charity sector, promoted by bodies including NCVO and NPC (New Philanthropy Capital).
A logic model is read left to right (or top to bottom) and contains five linked components:
| Component | What it means | Example |
|---|---|---|
| Inputs | Resources invested in the programme | Funding, staff time, volunteer hours, premises |
| Activities | What you do with those resources | Group sessions, one-to-one support, online training |
| Outputs | Direct, countable products of those activities | 150 sessions delivered; 300 participants reached |
| Outcomes | Changes experienced by participants | Improved confidence; new employment skills |
| Impact | Broader, longer-term change in the world | Reduced long-term unemployment in the local area |
The arrows between each component carry the real intellectual weight: they represent the assumptions — ideally backed by evidence — that justify expecting one stage to produce the next.
The W.K. Kellogg Foundation, whose Logic Model Development Guide is widely cited in the sector, describes a logic model as "a picture of how you believe your program will work" — a tool for thinking, planning, and communication throughout a programme's life. (W.K. Kellogg Foundation)
How a Logic Model Differs from a Theory of Change
Logic models and theories of change are closely related and the terms are sometimes used interchangeably. The practical distinction is one of depth and direction.
A logic model is primarily descriptive: it shows what is expected to happen and in what order. A theory of change is explanatory: it goes further to articulate why each step is expected to produce the next, making the causal assumptions explicit and drawing on research, practice evidence, and stakeholder knowledge.
Put simply: a logic model describes the chain; a theory of change justifies it.
Both tools are useful. Many charities build a theory of change first — to establish the reasoning — and then produce a logic model as a cleaner, more communication-friendly summary for funders and programme teams. Logic models are particularly well suited to grant applications and funder reports because their tabular or flowchart format is easy to read quickly.
According to NCVO, funders and supporters are increasingly expecting to see evidence of impact before committing resources, and a clear framework linking resources and activities to outcomes is central to demonstrating that evidence. (NCVO)
Once you have mapped your logic model, tools like Plinth's Impact Reporting help you collect and present the outcome data that brings each stage of the model to life.
When Funders Require a Logic Model
Grant-makers ask for logic models — or something equivalent — because they want confidence that an applicant has thought rigorously about how their programme works. A clearly articulated programme logic signals that delivery is likely to be coherent and that the applicant can report meaningfully on results.
The National Lottery Community Fund, which distributes over £600 million annually across the UK, uses the inputs-to-impact framework explicitly in its evaluation guidance and expects applicants to trace clear pathways from activities to outcomes. Many other major UK trusts and statutory commissioners use similar requirements, even when the terminology differs — questions such as "explain how your activities will lead to the outcomes you have identified" are asking for the same reasoning in narrative form.
For smaller grants, funders often accept a simplified one-page version. For larger or multi-year programmes, a more detailed logic model — potentially accompanied by a full theory of change — is typically expected.
Knowing what to measure is one of the most immediate practical benefits of building a logic model: by defining your outcomes and outputs clearly, you can design proportionate data collection from the outset rather than retrofitting evaluation later.
Frequently Asked Questions
Is a logic model the same as a theory of change?
Not exactly, though the terms are often used interchangeably. A logic model is a simpler, more linear diagram focused on what will happen at each stage. A theory of change includes the why — the assumptions and evidence that explain why one stage should lead to the next. A logic model is often derived from or summarises a fuller theory of change. See our detailed comparison in the Logic Model for Charities: The Complete Guide.
Do small charities need a logic model?
Yes — but it does not need to be complex. A straightforward one-page table or flowchart setting out your inputs, activities, outputs, and intended outcomes is sufficient for most small-grant applications. The process of creating it is often as valuable as the document itself, helping teams clarify exactly what they are trying to achieve and for whom.
What software do charities use to build logic models?
Many charities start with a table in a word processor or a basic flowchart tool. Once programmes are running, monitoring and evaluation software — including platforms like Plinth — can help you structure data collection around each component of your logic model and generate funder-ready impact reports.
Recommended Next Pages
Logic Model for Charities: The Complete Guide — Step-by-step guidance on building, testing, and using a logic model, with a worked example.
What is a Theory of Change? — How theories of change relate to logic models, and when to use each.
What are Outcomes and Outputs? — Understanding the critical difference between what you deliver and the change you create.
Monitoring and Evaluation Software for Charities — Tools that help you collect outcome data against each stage of your logic model.
Published by the Plinth Team. Last updated 21 February 2026.