Charitable Donation Tax Savings Calculator — Rex's Toolbox

Rex says

Money math without the spreadsheet headache. Plug in your numbers and I'll show you exactly where the dollars land.

Try a scenario

Click to load — tweak from there.

Inputs

Charitable gift($)

Other itemized deductions($)

Your standard deduction($)

Federal marginal bracket

State marginal rate(%)

Unrealized gain if donating stock($)

Capital gains rate(%)

Result

After-tax cost of the gift

$10,000

Total tax saved

Deductible amount that actually counts

Capital gains tax avoided

Effective subsidy rate

0.0%

Should you itemize?

No — standard deduction is larger

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How to use this

1Enter charitable gift ($).
2Enter other itemized deductions ($).
3Enter your standard deduction ($).
4Enter federal marginal bracket.
5Enter state marginal rate (%).
6Enter unrealized gain if donating stock ($).
7Enter capital gains rate (%).
8Read your after-tax cost of the gift on the right — it updates as you type.
9Hit Share to keep the scenario or send it to someone.

About this calculator

A deduction only helps if you itemize, and only for the amount above the standard deduction. This estimates the federal and state tax saved by a gift and shows the true after-tax cost. Estimates only — confirm with a tax professional.

FormulaTax saved = deductible amount × (federal marginal rate + state rate); net cost = gift − tax saved.

Worked example

Using the values the calculator loads with:

Inputs

Charitable gift: 10000 $
Other itemized deductions: 16000 $
Your standard deduction: 30000 $
Federal marginal bracket: 24%
State marginal rate: 5 %
Unrealized gain if donating stock: 0 $
Capital gains rate: 15 %

Results

After-tax cost of the gift: $10,000
Total tax saved: $0
Deductible amount that actually counts: $0
Capital gains tax avoided: $0
Effective subsidy rate: 0.0%
Should you itemize?: No — standard deduction is larger

What each field means

Inputs

Charitable gift ($): The charitable gift used in the calculation, measured in $. Starts at 10000 $ so you have a working example on load.
Other itemized deductions ($): The other itemized deductions used in the calculation, measured in $. Starts at 16000 $ so you have a working example on load.
Your standard deduction ($): The your standard deduction used in the calculation, measured in $. Starts at 30000 $ so you have a working example on load.
Federal marginal bracket: Pick the option that matches your situation — the maths changes per option. Choices: 10%, 12%, 22%, 24%, 32%, 35%, 37%.
State marginal rate (%): The state marginal rate used in the calculation, measured in %. Starts at 5 % so you have a working example on load. Accepted range: 0–15 %.
Unrealized gain if donating stock ($): The unrealized gain if donating stock used in the calculation, measured in $. Starts at 0 $ so you have a working example on load.
Capital gains rate (%): The capital gains rate used in the calculation, measured in %. Starts at 15 % so you have a working example on load. Accepted range: 0–40 %.

Results

After-tax cost of the gift: Returned as a money amount in US dollars and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
Total tax saved: Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
Deductible amount that actually counts: Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
Capital gains tax avoided: Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
Effective subsidy rate: Returned as a percentage. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
Should you itemize?: Returned as a plain value. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.

FAQ

Why does my gift sometimes save nothing?

Because the standard deduction is large. If your other itemized deductions are well below it, the first several thousand dollars of giving only closes the gap and produces no incremental tax benefit.

What is bunching?

Combining two or three years of giving into one tax year — often through a donor-advised fund — so that year clears the standard deduction while the others take the standard. It can recover most of the lost benefit.

Accuracy and limitations

Results are estimates before tax, fees, and inflation unless an input explicitly covers them.
Rates are treated as fixed for the whole period — variable-rate products will drift from this projection.
This is educational maths, not financial advice. Check anything contractual with the lender or your accountant.

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Cite this calculator

Writing about this topic? Grab a citation — every link helps keep these tools free.

APA

RevenueLab. (2026). Charitable Donation Tax Deduction Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/charitable-deduction

HTML

<p>Source: <a href="https://www.revenuelab.fyi/toolbox/charitable-deduction" target="_blank" rel="noopener">Charitable Donation Tax Deduction Calculator — RevenueLab</a> (2026).</p>

Markdown

Source: [Charitable Donation Tax Deduction Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/charitable-deduction) (2026).