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
Higher net value account
HSA
HSA total value (with growth)
$16,081
FSA total net savings
$4,200
Difference over horizon
$11,881
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How to use this
- 1Enter annual contribution ($).
- 2Enter marginal tax rate (%).
- 3Enter employer hsa contribution ($).
- 4Enter expected fsa forfeiture (%).
- 5Enter years to project (hsa growth).
- 6Enter hsa investment growth rate (%).
- 7Read your higher net value account on the right — it updates as you type.
- 8Hit Share to keep the scenario or send it to someone.
About this calculator
An HSA offers triple tax advantages and unlimited rollover but requires a high-deductible health plan, while an FSA lowers your taxable income too but is typically use-it-or-lose-it each year. This tool compares your effective tax savings from contributions, the value of any employer match, and the cost of unused-funds forfeiture to show which account nets you more over your planning horizon.
Worked example
Using the values the calculator loads with:
Inputs
- Annual contribution: 3000 $
- Marginal tax rate: 24 %
- Employer HSA contribution: 500 $
- Expected FSA forfeiture: 10 %
- Years to project (HSA growth): 10
- HSA investment growth rate: 6 %
Results
- Higher net value account: HSA
- HSA total value (with growth): $16,081
- FSA total net savings: $4,200
- Difference over horizon: $11,881
What each field means
Inputs
- Annual contribution ($)
- The annual contribution used in the calculation, measured in $. Starts at 3000 $ so you have a working example on load.
- Marginal tax rate (%)
- The marginal tax rate used in the calculation, measured in %. Starts at 24 % so you have a working example on load. Accepted range: 0–50 %.
- Employer HSA contribution ($)
- The employer hsa contribution used in the calculation, measured in $. Starts at 500 $ so you have a working example on load.
- Expected FSA forfeiture (%)
- The expected fsa forfeiture used in the calculation, measured in %. Starts at 10 % so you have a working example on load. Accepted range: 0–100 %.
- Years to project (HSA growth)
- The years to project (hsa growth) used in the calculation. Starts at 10 so you have a working example on load. Accepted range: 1–30.
- HSA investment growth rate (%)
- The hsa investment growth rate used in the calculation, measured in %. Starts at 6 % so you have a working example on load. Accepted range: 0–15 %.
Results
- Higher net value account
- Returned as a plain value and shown as the headline result. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- HSA total value (with growth)
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- FSA total net savings
- Returned as a money amount in US dollars. It recalculates instantly whenever you change an input, so you can compare scenarios without reloading.
- Difference over horizon
- 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 have both an HSA and FSA?
Generally no — you can't contribute to a standard HSA and a general-purpose FSA in the same year, though a limited-purpose FSA (dental/vision only) can be paired with an HSA.
What happens to unused HSA funds?
They roll over indefinitely and stay yours even after you change jobs or retire, unlike most FSAs which reset annually with only a small carryover or grace period allowed.
Is an HSA worth it if I rarely have medical expenses?
Yes — it functions as a stealth retirement account since unused funds can be invested and withdrawn penalty-free for any reason after age 65, taxed like a traditional IRA.
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
Cite this calculator
Writing about this topic? Grab a citation — every link helps keep these tools free.
RevenueLab. (2026). HSA vs FSA Savings Calculator. Retrieved from https://www.revenuelab.fyi/toolbox/hsa-vs-fsa-savings-cost
<p>Source: <a href="https://www.revenuelab.fyi/toolbox/hsa-vs-fsa-savings-cost" target="_blank" rel="noopener">HSA vs FSA Savings Calculator — RevenueLab</a> (2026).</p>
Source: [HSA vs FSA Savings Calculator — RevenueLab](https://www.revenuelab.fyi/toolbox/hsa-vs-fsa-savings-cost) (2026).