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
Result
Estimated SSDI monthly benefit
$2,121
Estimated SSI monthly benefit (if only SSI)
$943
Possible SSI top-up if also on SSDI
$0
Countable income used in SSI calc
$0
Federal benefit rate + supplement used
$943
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How to use this
- 1Enter average indexed monthly earnings (aime) ($).
- 2Enter other unearned monthly income ($).
- 3Enter monthly earned income (if any) ($).
- 4Enter ssi federal benefit rate (individual) ($).
- 5Enter state ssi supplement ($).
- 6Read your estimated ssdi monthly benefit on the right — it updates as you type.
- 7Hit Share to keep the scenario or send it to someone.
About this calculator
SSDI and SSI are both administered by the Social Security Administration but work completely differently. SSDI is an earned benefit funded by your payroll taxes, paid based on your work credits and average lifetime earnings, with no asset limit and monthly amounts that can reach the same range as retirement benefits. SSI is a needs-based program funded by general tax revenue, has a strict $2,000/$3,000 individual/couple asset limit, and pays a flat federal benefit rate (plus state supplement) that gets reduced by other income. You can qualify for both concurrently if your SSDI is low enough. This calculator gives a rough side-by-side estimate: SSDI from your estimated average indexed monthly earnings using a simplified bend-point approach, and SSI from the federal benefit rate minus countable income, so you can see which program (or combination) likely applies. Actual determinations require SSA's full formulas, state supplements, and a formal disability determination — this is directional only.
Worked example
Using the values the calculator loads with:
Inputs
- Average indexed monthly earnings (AIME): 4500 $
- Other unearned monthly income: 0 $
- Monthly earned income (if any): 0 $
- SSI federal benefit rate (individual): 943 $
- State SSI supplement: 0 $
Results
- Estimated SSDI monthly benefit: $2,121
- Estimated SSI monthly benefit (if only SSI): $943
- Possible SSI top-up if also on SSDI: $0
- Countable income used in SSI calc: $0
- Federal benefit rate + supplement used: $943
What each field means
Inputs
- Average indexed monthly earnings (AIME) ($)
- The average indexed monthly earnings (aime) used in the calculation, measured in $. Starts at 4500 $ so you have a working example on load.
- Other unearned monthly income ($)
- The other unearned monthly income used in the calculation, measured in $. Starts at 0 $ so you have a working example on load.
- Monthly earned income (if any) ($)
- The monthly earned income (if any) used in the calculation, measured in $. Starts at 0 $ so you have a working example on load.
- SSI federal benefit rate (individual) ($)
- The ssi federal benefit rate (individual) used in the calculation, measured in $. Starts at 943 $ so you have a working example on load.
- State SSI supplement ($)
- The state ssi supplement used in the calculation, measured in $. Starts at 0 $ so you have a working example on load.
Results
- Estimated SSDI monthly benefit
- 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.
- Estimated SSI monthly benefit (if only SSI)
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Possible SSI top-up if also on SSDI
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Countable income used in SSI calc
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Federal benefit rate + supplement used
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
FAQ
Can I get both SSDI and SSI at the same time?
Yes, this is called concurrent benefits. It applies when your SSDI payment is low (because your lifetime earnings were low) and you also meet SSI's strict $2,000 asset limit. SSA pays SSDI first, then tops it up with SSI up to the federal benefit rate minus countable income.
Why does SSI have an asset limit and SSDI doesn't?
SSDI is insurance you paid into through FICA taxes on your paycheck, like a pension — your assets don't matter because you earned the right to it through work credits. SSI is welfare-style aid funded by general tax revenue, designed only for people with very limited resources, so assets and other household income are strictly counted.
How many work credits do I need for SSDI?
Generally 40 credits (about 10 years of work), with 20 earned in the last 10 years before you became disabled, though younger workers need fewer. Credits are earned per year of sufficient wages, capped at 4 per year, so the requirement scales with age at disability onset.
Does SSDI convert to retirement benefits later?
Yes, at full retirement age SSDI automatically converts to a Social Security retirement benefit at the same dollar amount — there's no cliff or reapplication needed, it's essentially a relabeling of the same payment.
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.
Related tools
Social Security Earnings Test Calculator
See how much Social Security withholds if you claim early and keep working.
Social Security Spousal Benefit Calculator
Estimate your spousal Social Security benefit based on your spouse's record.
WEP/GPO Impact Estimator
Estimate how a non-covered government pension could reduce your Social Security.
Cite this calculator
Writing about this topic? Grab a citation — every link helps keep these tools free.
RevenueLab. (2026). SSDI vs SSI Comparison Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/ssdi-vs-ssi-comparison
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/ssdi-vs-ssi-comparison" target="_blank" rel="noopener">SSDI vs SSI Comparison Calculator — RevenueLab</a> (2026).</p>
Source: [SSDI vs SSI Comparison Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/ssdi-vs-ssi-comparison) (2026).