What Is Impact Measurement for Charities?

Impact measurement is how charities establish what difference their work actually makes — not just what they do, but what changes as a result. It involves collecting evidence, analysing it against a clear framework, and communicating findings to funders, trustees, and beneficiaries. Most funders now require it, and the sector bodies NPC, NCVO, and the Inspiring Impact programme have developed extensive guidance to help organisations of all sizes do it well.

What Is the Difference Between Outputs and Impact?

This is the question at the heart of impact measurement, and getting it wrong is the most common mistake charities make.

Outputs are what your organisation does: the number of sessions delivered, meals served, people seen, hours of support provided. They are relatively easy to count and important as a record of activity. But they say nothing about what changed.

Outcomes are the changes that result from your work — shifts in knowledge, behaviour, skills, confidence, circumstances, or wellbeing. Outcomes happen to or within the people, communities, or systems you work with.

Impact goes one step further: it is the portion of that change that is attributable to your work specifically, accounting for what would have happened anyway (known as deadweight) and the contributions of other organisations. As NPC — the charity think tank that has worked with hundreds of charities on measurement frameworks — explains it: impact is the difference your organisation makes in the world, over and above what would have happened without you.

A practical example: a financial capability charity that runs workshops might count 800 sessions delivered (output) and report that 74% of participants improved their budgeting behaviour (outcome). Its impact is the proportion of that 74% that resulted from its sessions, rather than from other factors such as wider economic changes or other services.

According to a 2012 NPC survey, almost 25% of charities did not measure impact at all — a figure that was higher among smaller organisations. Sector bodies have worked to address this, though capacity and resource constraints remain real barriers, particularly for micro and small organisations. According to the NCVO UK Civil Society Almanac 2024, 80% of voluntary organisations have income under £100,000, and proportionate measurement approaches are essential for this majority.

The Main Frameworks: Theory of Change, SROI, Social Value, and the Outcomes Star

There is no single mandatory approach to impact measurement. Instead, several complementary frameworks have become established across the UK charity sector. Most organisations use a combination.

Theory of Change

A Theory of Change is a map of how your organisation expects to create change. It sets out your assumptions: if you do X with resource Y, then Z will happen, because of A, B, and C. It connects your inputs and activities to your intended outputs, outcomes, and long-term impact.

As NCVO's guidance puts it, a Theory of Change helps an organisation "articulate what it is trying to achieve and why it believes its approach will work." It is both a planning tool and a measurement tool — once you have made your theory explicit, you know what to measure and why.

A decade ago the term was largely unfamiliar in the UK voluntary sector. Today it is a standard requirement in most competitive grant applications, and NPC has published a widely used guide to developing one. The key discipline is being specific: vague causal chains ("we support people, therefore their lives improve") are not useful. A good Theory of Change names the mechanisms of change and the evidence that supports them.

Social Return on Investment (SROI)

SROI is a framework that assigns financial values to social outcomes, comparing the total value generated against the cost of investment. The result is a ratio: an SROI of 4:1 means that for every £1 invested, £4 of social value was created.

The framework is governed by Social Value UK (formerly the SROI Network), which publishes the Guide to SROI and eight core principles, including stakeholder involvement, understanding what changes, and being transparent about what is and is not included. SROI can be conducted as a forecast (before a programme runs) or as an evaluative analysis (after it has run).

SROI is particularly useful for demonstrating value to commissioners and public sector funders. However, it requires significant time, skill, and access to financial proxies, and is better suited to larger organisations or specific programmes rather than whole-organisation measurement. Critics also note that attaching financial values to social outcomes involves inherent subjectivity, which is why transparency about methodology is one of the core principles.

Social Value

The Public Services (Social Value) Act 2012 requires public bodies in England and Wales to consider economic, social, and environmental wellbeing when commissioning services. Since 2021, central government procurement has required a minimum 10% weighting for social value in tender evaluations under PPN 06/20, a requirement carried forward through the Procurement Act 2023. Many individual contracting authorities now apply weightings of 20% or higher in practice.

For charities that contract with the public sector — including housing associations, health and social care providers, and employment services — demonstrating social value using recognised frameworks is now a contractual requirement, not a voluntary aspiration. Social Value UK's national TOMS (Themes, Outcomes, Measures) framework and the government's own Social Value Model provide standardised measurement approaches.

The Outcomes Star

The Outcomes Star is a family of measurement tools developed by Triangle Consulting Social Enterprise, designed specifically for use in keywork and support relationships. Each Star presents a set of outcome areas — typically five to ten — on a visual wheel, with a scale from 1 (stuck) to 10 (thriving) in each area. Practitioners and service users complete the Star together, making it both a measurement tool and a support planning tool.

More than six million Stars have been completed to date, and Triangle reports that over 60 research studies have validated the tool's psychometric properties, including its internal consistency, responsiveness to change, and predictive validity. There are versions for homelessness, mental health, recovery, employment, family support, and many other contexts.

The Outcomes Star is particularly valuable because it captures change over time from a person-centred perspective. When combined with aggregated data from Plinth's Impact Reporting, organisations can track progress across entire caseloads and generate evidence of outcomes for funders.

Why Funders Require Impact Measurement

Funder requirements have become one of the primary drivers of impact measurement across the sector. Whether the funder is a charitable trust, a statutory commissioner, or an individual philanthropist, the expectation that grantees will demonstrate outcomes has become standard.

There are several reasons for this. First, funders face their own accountability requirements — to their own trustees, donors, or government — and need evidence that their investments are effective. Second, the growth of outcome-based commissioning in public services means that payment is increasingly linked to demonstrated results. Third, growing awareness of the difference between charitable activity and genuine social change has raised expectations about the quality of evidence.

The Inspiring Impact programme — a collaboration between NPC, NCVO, Social Value UK, Evaluation Support Scotland, Community Evaluation Northern Ireland, and the Wales Council for Voluntary Action — set out to make high-quality impact measurement the norm for UK charities. Its Code of Good Impact Practice established eight principles, including taking responsibility for impact, involving stakeholders, and being honest and open about findings. Although the formal Inspiring Impact programme has now closed, its resources remain available through NPC's website, and the code continues to be widely referenced.

NCVO's own consultancy supports charities in developing measurement approaches proportionate to their size and resources, and its Road Ahead 2025 report noted that funders are increasingly expecting formal evaluation of outcomes — not just activities — even from smaller organisations.

For charities, the practical implication is that impact measurement is no longer something you do if you have the capacity; it is something you need to do to access funding. Plinth's Surveys feature can help organisations collect the beneficiary and stakeholder data that underpins credible outcome reporting, without adding significant administrative burden to frontline staff.

Common Challenges in Impact Measurement

Understanding the frameworks is one thing. Putting them into practice consistently is another. The most common challenges fall into four categories.

Attribution. Demonstrating that your work — rather than other factors — caused the change you are observing is genuinely difficult. Rigorous approaches use control groups or comparison populations, but these are often impractical for service organisations. Honest reporting acknowledges this limitation and describes the steps taken to mitigate it, such as asking beneficiaries what else might have contributed to their progress.

Long-term outcomes. Many of the most significant changes that charities work towards — sustained employment, long-term recovery, educational attainment — take years to manifest. Short funding cycles make it difficult to track outcomes beyond the end of a contract. Building follow-up touchpoints into service design, and using tools like the Outcomes Star to capture progress at interim stages, can help.

Staff capacity and data systems. Collecting outcome data consistently requires trained staff, clear processes, and systems that make recording straightforward rather than burdensome. Research from NPC found that grantees often have limited data capacity and no dedicated monitoring and evaluation staff. Integrating data collection into existing workflows — rather than treating it as a separate task — is essential for consistency.

Proportionality. NPC's guidance for small charities, Keeping It in Proportion, makes the point explicitly: measurement approaches should match the organisation's size and the scale of the decision being made. A micro charity with a £40,000 budget should not be expected to conduct an SROI analysis. Starting with a clear Theory of Change, a handful of outcome indicators, and a simple survey tool is both sufficient and achievable.

Frequently Asked Questions

What is the simplest way to start measuring impact?

Start with your Theory of Change. Identify three to five outcomes you expect your work to produce, and for each one define an indicator — something observable that tells you whether the outcome has occurred. Then decide how you will collect that data: through surveys, keywork records, referral feedback, or the Outcomes Star. NCVO's impact planning support and NPC's Building a Measurement Framework guide are both good starting points and available free online. You do not need a sophisticated system on day one; you need a clear, honest logic and consistent data collection habits.

What is the difference between monitoring and evaluation?

Monitoring is the ongoing, systematic collection of data about your activities and outcomes — it happens throughout a programme. Evaluation is a periodic, more structured assessment of what you have found and what it means, often involving comparison against targets or external benchmarks. Both are important. Monitoring gives you real-time feedback to improve services; evaluation gives you the evidence base to report to funders and learn at a strategic level. The Inspiring Impact Code of Good Impact Practice emphasises that measurement should lead to action — the data should change what you do, not just what you report.

Do we need to demonstrate impact for every single activity?

No. Proportionality is a core principle in NPC and NCVO guidance alike. Not every piece of work warrants the same level of scrutiny. Apply the most rigorous measurement approaches to your largest, most resource-intensive programmes or those that are highest stakes for beneficiaries. For smaller activities or short-term work, a lighter approach — activity records, brief beneficiary feedback, and honest reflection — is appropriate. The goal is a credible overall picture of your impact, not perfect evidence for every action.

Recommended Next Pages

• What Are Outcomes and Outputs? — The foundational distinction explained in full
• What Is a Theory of Change? — How to develop a Theory of Change for your organisation
• What Is the Outcomes Star? — A detailed guide to Triangle Consulting's measurement tool
• Monitoring and Evaluation Software for Charities — How to choose a system that fits your organisation

Published by the Plinth Team. Last updated 21 February 2026.