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SROI calculator: work out social return on investment step by step

SROI (social return on investment) is a framework that values the change an activity creates for stakeholders in money terms and compares it with the investment; the result reads as "X of social value per 1 invested". This free calculator applies the calculation chain of "A guide to Social Return on Investment" (2012), published today by the Institute for Social Value (formerly Social Value UK), and shows the ratio, present value, NPV, payback period and sensitivity as you type.

For each outcome you enter a quantity and a financial proxy; the tool deducts deadweight, displacement and attribution, applies drop-off over the outcome's duration and discounts every year. Because it runs on your own estimates, the output is a forecast SROI, not an assured analysis.

The 3.5% default is the HM Treasury Green Book rate the guide cites [1][6]. The guide also calls discounting controversial, because discounting the future can encourage short-termism. Choose a rate that fits your context and give your reasons in the report.

How is it calculated?

The tool applies steps 4.4 and 5.1-5.5 of the guide in order [1].

Total value (quantity × financial proxy): In the guide's example, 16 × £48.25 = £772.00.
Deadweight (× (1 − deadweight)): Removes change that would have happened anyway: £772 × 0.9 = £694.80. 100% deadweight sets the impact to zero, but the row stays on the map.
Displacement (× (1 − displacement)): Where it applies, removes the share that displaced outcomes elsewhere.
Attribution (× (1 − attribution)): Removes others' contribution: £694.80 × 0.65 = £451.62. This is the row's year-1 impact.
Drop-off (year 1 × (1 − drop-off)^(t − 1)): If an outcome lasts more than a year, a fixed share is deducted from the remaining level each year: £1,539.00 → £1,385.10 → £1,246.59.
Present value (Σ year total / (1 + r)^t): Year 1 is discounted too. Same as Excel's =NPV(r, value1, value2, …).
NPV and ratios (NPV = PV − investment; SROI = PV / investment; net SROI = NPV / investment): Guide's example: £81,741.93 / £42,375 = £1.93 : £1.
Payback (investment / (annual impact / 12)): In months; an optional step in the guide.

The six stages of an SROI analysis

The calculator only does the arithmetic of stages 4 and 5. Scoping, stakeholder involvement and reporting carry most of the work [1].

Establishing scope and identifying key stakeholders: Decide what the analysis covers, who will be involved and how, whether it is a forecast or an evaluation, and what period it covers.
Mapping outcomes: Build an impact map (theory of change) with stakeholders, linking inputs, outputs and outcomes. The value of inputs, the investment, is recorded here.
Evidencing outcomes and giving them a value: Find indicators and data showing whether outcomes happened, set how long each lasts, and give each a financial proxy.
Establishing impact: Remove change that would have happened anyway or came from other factors: deadweight and displacement, attribution, drop-off, then calculate impact.
Calculating the SROI: Project value into the future, calculate net present value and the ratio, run sensitivity analysis and, optionally, the payback period.
Reporting, using and embedding: Share findings with stakeholders and respond to them, embed good outcomes processes, and have the report verified.

The eight principles of social value

Social Value International's principles. The 2012 guide lists the first seven; the eighth was added in 2021 [4][5].

Involve stakeholders: The people or organisations that experience change help decide what is measured and how it is valued.
Understand what changes: Explain how change is created and evaluate it with evidence, covering positive and negative, intended and unintended change.
Value the things that matter: Value outcomes by their relative importance to stakeholders. The 2012 guide frames this as using financial proxies so that non-market outcomes are recognised.
Only include what is material: Include the information and evidence needed for a true and fair picture; information is material if leaving it out would change a decision.
Do not overclaim: Claim only the value the activities are responsible for: use trends and benchmarks, and account for what would have happened anyway and for others' contributions.
Be transparent: Show why the analysis can be considered accurate and honest, and that it will be reported to and discussed with stakeholders. Document every judgement.
Verify the result: Get appropriate independent assurance. Current wording asks for verification proportionate to the decision, with independent assurance for external reporting or significant decisions.
Be responsive: Pursue optimum social value through timely decisions supported by appropriate accounting and reporting, which means acting on what social value accounts show.

How to read this result

Do not compare ratios across organisations. The guide says organisations work with different stakeholders and make different judgements, so comparing social return ratios alone is not appropriate. An organisation should compare changes in its own ratio over time [1].
There are two types of SROI. An evaluative SROI looks back at actual outcomes; a forecast SROI predicts the value created if activities meet their intended outcomes. Running on your own estimates, this tool is a forecast aid [1].
Every deduction is an estimate. Without better information the guide accepts rounding to the nearest 10% and warns against chasing false accuracy [1].
A calculator output is not an assured SROI. SROI involves subjectivity, which is why principle 7 asks for independent assurance [1][4].
Take care with unit costs as proxies for savings: fixed costs do not change, so marginal savings are usually lower than the full unit cost [1].
SROI is less useful when stakeholders are not interested in the results, or when it is done only to prove value with no chance to change practice [1].

Where to find financial proxies

This tool ships no values from any database; you enter the proxies. Check licence terms when you choose a source.

Global Value Exchange (GVE): A crowd-sourced database of outcomes, indicators and valuations, which the 2012 guide names as the successor to the SROI Network's VOIS database. GVE says its data is freely available for use but not quality-assured, and its accuracy is not guaranteed [1][7].
HACT UK Social Value Bank: Holds 88 outcomes valued with wellbeing valuation. It needs a licence: HACT asks users to contact it before using the bank, so none of its values are in this tool [8][9].
HM Treasury Green Book: UK government appraisal guidance; the source of the 3.5% discount rate and of wellbeing valuation guidance. Published under the Open Government Licence [6].
IRIS+ (GIIN): Listed in the 2012 guide's resources as a catalogue of impact metrics. It offers indicators, not financial proxies [1].

Frequently asked questions

How is the SROI ratio calculated?

The SROI ratio is the total present value of outcomes divided by the investment. For each outcome, quantity is multiplied by a financial proxy, deadweight, displacement and attribution are deducted, drop-off reduces it over the years it lasts, and each year is discounted. The guide's worked example gives £81,741.93 / £42,375 = £1.93 : £1.

Can we compare our SROI ratio with another organisation's?

No. The SROI guide says organisations work with different stakeholders and make different judgements, so comparing ratios alone is not appropriate. A meaningful comparison is the same organisation's ratio over time, and even that needs the assumptions behind each report.

Which discount rate should an SROI use?

The guide cites the 3.5% rate recommended in HM Treasury's Green Book for the public sector and uses it in its examples. This tool defaults to 3.5% as well. Outside the UK public sector, choose a rate that fits your context and explain it in the report.

What is the difference between deadweight and attribution?

Deadweight is the share of the outcome that would have happened even without the activity. Attribution is the share of the change that came from other organisations or people. The guide deducts deadweight first, then attribution; if the deadweight benchmark already reflects others' contributions, do not deduct the same share twice.

Does this calculator replace an SROI report?

No. It runs on your estimates, so its output is a forecast SROI. A real analysis needs stakeholder engagement, outcome data, sourced proxies, sensitivity analysis and independent assurance. The calculator helps you see how your assumptions drive the result and plan what to measure.

Sources

The SROI Network (Nicholls, Lawlor, Neitzert, Goodspeed; ed. Cupitt), hosted by ISV. A guide to Social Return on Investment (January 2012 update) (2012-01). Accessed: 2026-10-15.
Cabinet Office, Office of the Third Sector (hosted by fi-compass). A guide to Social Return on Investment (2009) (2009). Accessed: 2026-10-15.
Institute for Social Value (ISV, formerly Social Value UK). A Guide to Social Return on Investment 2012. Accessed: 2026-10-15.
Social Value International. The Principles of Social Value. Accessed: 2026-10-15.
Social Value International. Principle 8: Be Responsive. Accessed: 2026-10-15.
HM Treasury. The Green Book (2026) (2026). Accessed: 2026-10-15.
Global Value Exchange. Global Value Exchange. Accessed: 2026-10-15.
HACT. UK Social Value Bank. Accessed: 2026-10-15.
HACT. Licensing conditions for the UK Social Value Bank. Accessed: 2026-10-15.