GWWC's 2025 impact evaluation (executive summary)

By Aidan Whitfield🔸, Giving What We Can🔸 @ 2026-06-30T11:35 (+83)

This post presents the executive summary from Giving What We Can’s impact evaluation for 2025. At the end of this post we share links to more information, including the full report and working sheet for this evaluation. We look forward to your questions and comments!

Executive summary

Giving What We Can (GWWC) is working towards a world without preventable suffering or existential risk, where everyone is able to flourish. We do this by making effective and significant charitable giving a norm among those who can — primarily through our flagship program: the 🔸10% Pledge, a lifetime commitment to give at least 10% of income to highly effective charities. Annually, our growing community of roughly 20K donors and pledgers records over $80M USD in charitable donations with GWWC. 

As an organisation that advocates for effective giving, we think it is important to hold ourselves to the same standard. This report is our third impact evaluation of this type and examines the cost effectiveness of ourselves as an organisation in 2025.

Our headline findings and estimates:

• Our 2025 giving multiplier was 7x — GWWC produced $16M in value for highly effective charities in 2025, at a cost of $2.3M to our funders — meaning for the average $1 spent, we caused $7 in donations to highly effective charities. This is up from 6x in our previous evaluation.
• This improvement was driven by significant growth — in 2025, new 10% Pledges grew 24% and new Trial Pledges grew 43%. The volume of pledge donations GWWC caused to go to high-impact charities increased by 35%.
• The 🔸10% Pledge remains a strong driver of effective giving — the average new 10% pledger will donate roughly $100K over their lifetime. After adjustments, we estimate $15K of this is impactful giving attributable to GWWC's work — broadly stable from our previous estimate, despite major updates to our modelling.
• 🔹Trial Pledges are more valuable than we previously thought — our estimate has more than doubled to $5K per Trial Pledge, driven by our finding that trial pledgers who go on to take a 10% Pledge exhibit much higher retention rates than average 10% pledgers.
• Pledger retention is a significant lever for increasing our impact — 10% Pledge attrition is faster than we previously estimated, and pledgers who stay give more over time, making retention efforts more valuable.
• We have updated our guidance on Trial Pledge acquisition value — we now recommend that GWWC and pledge partners attribute $2K to the work of acquiring a new Trial Pledge (up from $1K). Our 10% Pledge acquisition guidance is unchanged at $10K.
• We have growing evidence that GWWC influences some very large pledge donors — while the largest volume of donations comes from donors in the $10–100K bracket, several pledge donors now giving at the $1M+ level report that GWWC affects the amount they give.

These estimates have important limitations: our multiplier measures average historical cost effectiveness, not future or marginal returns; we do not capture all of our impact; and our analysis relies on modelling and survey data that is inherently uncertain. We discuss these limitations throughout the report.

Where you can learn more

• Our full impact evaluation report — this includes a much more detailed description of our assumptions, considerations, methodology, and results.
  • More about our giving multiplier
  • More about the value of our pledges
• Our working sheet, where we combine our inputs to calculate our results.
• Our donation classification sheet, where we categorised pledge donation recipients to estimate our effectiveness coefficients and to assess pledge giving by cause.

Mo Putera @ 2026-06-30T14:42 (+14)

Yet another banger of a report! Awesome stuff.

I asked Claude to create an interactive dashboard version and to "make it similarly aesthetically pleasing":

Pledge values:

Sensitivities:

Build your own multiplier:

You should definitely trust the actual report over this dashboard, if you see something funny blame Claude... 

huw @ 2026-07-01T09:33 (+4)

(Just realising I am developing an eye for AI-generated graphics now, to complement my eye for AI-generated text, images, and videos. There’s something so familiar about this style.)

Mo Putera @ 2026-07-01T11:40 (+2)

It can't help it too. Here's the CoT from a microsite I asked Claude to build recently:

The frontend-design skill is warning me away from exactly the palette I was about to use—cream background, serif display, terracotta accent—which it flags as a common AI default. I need to reject that instinct and make a real aesthetic choice that's specific to this project, not a templated solution. ...

Yet the resulting aesthetics were still unmistakably Claudey. Aesthetics taste seems quite the bulwark. 

Aidan Whitfield🔸 @ 2026-07-02T08:34 (+3)

Thanks, Mo! The dashboard is really cool - maybe we should even build something like this for next year's evaluation.