Donation Impact Calculator
A donation's real impact depends on the charity's cost per outcome, any employer match, and your tax situation. This calculator adds your gift to its match to get the total reaching the charity, divides by the cost per unit of impact that the charity publishes (meals, vaccines, trees, or any unit), and estimates the tax saving from your own donation at your marginal rate. Every figure is your input, so the result reflects the organisation's reported efficiency and your circumstances, not an assumption.
Donation impact formula
Total to charity = donation * (1 + match / 100)
Units funded = total to charity / cost per unit
Tax saving = donation * tax rate / 100
Net cost to you = donation - tax saving
The match multiplies only the dollars reaching the charity. Units funded divides that total by the charity's published cost per outcome. The tax saving applies to your own gift only, and net cost is your donation less that saving.
Charitable giving context
- The IRS allows deductions for gifts to qualified charities when you itemise; rules and limits apply.
- Tax-exempt status can be checked with the IRS Tax Exempt Organization Search.
- Reputable charities publish a cost per outcome; use that figure for the units input.
- Employer match programs commonly match dollar for dollar up to an annual cap.
- Only your own donation, not the employer match, supports your tax deduction.
Donation impact: frequently asked questions
How does the calculator find my donation's impact?
It divides your total gift (your donation plus any employer match) by the cost per unit of impact that the charity publishes, such as cost per meal, vaccine or tree. The result is the number of units your gift funds. Because you enter the cost per unit from the charity, the figure reflects that organisation's stated efficiency.
What is donation matching?
Many employers match charitable gifts dollar for dollar up to a limit. Enter your match rate as a percentage: 100 percent doubles your gift. The calculator adds the match to your donation before computing impact, so a US$100 gift with a 100 percent match funds units worth US$200.
How is the tax deduction estimated?
In the US, donations to qualified charities may be tax-deductible if you itemise. The estimated tax saving equals your donation times your marginal tax rate. A US$100 gift at a 24 percent marginal rate could reduce your tax by about US$24. Consult IRS guidance and a tax professional for your situation.
Where do cost-per-unit figures come from?
Reputable charities publish their cost per outcome (for example, cost per meal served). Use that published figure as the cost per unit input. This calculator never assumes a number; it uses what you enter so the impact estimate is grounded in the charity's own reporting.
Does the match count toward my tax deduction?
No. An employer match is the employer's gift, not yours, so only your own donation is used for the tax-saving estimate. The match is included only when calculating total impact units, because both dollars reach the charity.
Official sources
- U.S. Internal Revenue Service: Charitable Contribution Deductions.
- U.S. Internal Revenue Service: Tax Exempt Organization Search.
Reviewed by the CalculatorHub team, edited by James Graham, 16 June 2026. See our methodology.