What Is Quadratic Funding? A Beginner's Guide

Quadratic funding is a donation-matching mechanism where the amount of matching funds a project receives is calculated using the square of the sum of the square roots of individual contributions, rather than simply matching the total dollar amount donated — a formula that mathematically favors projects with many small, independent donors over projects backed by a few large ones, even when the raw dollar totals are similar.

This mechanism was designed specifically to address the public goods funding problem: traditional matching (matching every dollar donated equally regardless of source) doesn't distinguish between genuine broad community support and a single wealthy donor's individual preference, even though those two scenarios represent very different signals about a project's actual collective value.

The formula in plain terms

The core insight is that the matching pool is distributed based on the square of the sum of square roots of contributions to each project, not the sum of contributions itself. In practical terms, this means ten different people each donating $10 to a project generates a much larger matching bonus than one person donating the equivalent $100 total, because the formula rewards the number of unique contributors, not just the total amount raised. A project with broad, distributed grassroots support gets disproportionately more matching funds than a project with the same total donations concentrated among fewer donors.

A simplified worked example

Consider two projects each receiving $100 in direct donations from a matching round. Project A gets that $100 from ten separate donors giving $10 each. Project B gets the same $100 from a single donor. Under quadratic funding's formula, Project A's broad base of contributors causes it to receive a substantially larger share of the shared matching pool than Project B, even though both raised the identical direct-donation amount — reflecting the underlying design goal of rewarding breadth of genuine support rather than raw total dollars.

Scenario	Direct donations	Number of donors	Relative matching funds received
Project A	$100	10 donors ($10 each)	Higher — broad support
Project B	$100	1 donor ($100)	Lower — concentrated support

Where quadratic funding is used

Quadratic funding has been applied in ecosystem grants rounds where a shared matching pool (often funded by a protocol treasury, foundation, or DAO) is distributed across many community-nominated public goods projects based on how broadly the community itself chooses to support each one through small individual donations. This lets a funding body express a general commitment ("we'll match community-prioritized public goods") without needing to individually evaluate and rank every submitted project's merit themselves — the crowd's donation pattern does much of that prioritization work.

Sybil resistance: the mechanism's biggest vulnerability

Because quadratic funding specifically rewards the number of unique contributors, it creates a strong incentive for bad actors to split a single large donation across many fake identities (a sybil attack) to simulate broad grassroots support and capture a disproportionate share of matching funds that a genuinely broad-based project would otherwise have earned. Robust implementations require identity or uniqueness verification — proof-of-personhood systems, decentralized identity credentials, or other sybil-resistance techniques — to keep the mechanism honest, and rounds without adequate sybil protections have historically seen this exact gaming behavior reduce the mechanism's intended fairness.

Limitations beyond sybil attacks

Quadratic funding also depends entirely on having a meaningful matching pool to distribute in the first place — the mechanism only shapes how existing matching funds get allocated, it doesn't create new funding on its own. It also requires genuine donor participation and awareness to work as intended; a round with very few participating donors doesn't meaningfully reflect broad community sentiment regardless of the formula applied to whatever donations it does receive.

Who typically funds the matching pool

The matching pool itself — the funds actually distributed according to the quadratic formula — usually comes from a separate source than the individual donors: a protocol treasury, a foundation grant, or a coalition of ecosystem sponsors contributing specifically to support a funding round. This structure means individual donors' small contributions primarily function as a signal directing how the larger matching pool gets allocated, rather than being the primary source of funds projects ultimately receive — in many rounds, the matching pool substantially exceeds the total direct donations, meaning the quadratic weighting of small individual signals can move a disproportionately large amount of matching capital.

Running a round: practical implementation steps

Organizing a quadratic funding round typically involves a sponsor committing a matching pool amount, publishing eligibility criteria for which projects can participate, running the round over a defined donation window on a platform that calculates and displays live quadratic-weighted rankings, and implementing sybil-resistance checks (often requiring some form of identity verification or reputation score) before finalizing payouts. Participants can generally donate any amount they choose, and the platform handles the underlying quadratic calculation automatically, meaning donors don't need to understand the full mathematics to meaningfully participate.

Bottom line

Quadratic funding mathematically favors broad-based community support over concentrated large donations when allocating matching funds, making it a genuinely useful tool for crypto's public goods funding challenges, but its fairness depends heavily on robust sybil resistance and having real, broad donor participation to work as designed. See our public goods funding explainer for how this mechanism fits alongside retroactive funding and DAO grants programs.