HSA Growth Calculator
Project HSA growth for both medical expenses and retirement healthcare savings.
What this calculator does
This calculator projects a health savings account balance to retirement, treating it as the long-term investment account it can be rather than the spending account most people use it as. Enter your age, retirement age, current balance, monthly contribution and expected return, and it projects the balance forward alongside your expected annual medical expenses.
The gap between contributions and final balance is the argument for leaving an HSA invested. Money spent on current medical bills never compounds, while money left alone for thirty years multiplies several times over and can still emerge tax-free for healthcare costs in retirement.
When to use it
Run it when deciding whether to spend from the HSA or pay medical costs out of pocket and let the balance ride. That single decision, repeated over a career, separates an account worth a few thousand dollars from one worth several hundred thousand, and this calculator prices the difference.
It is also useful during open enrollment, when choosing between a high deductible plan with an HSA and a traditional plan. The premium saving plus any employer HSA contribution, invested rather than spent, often outweighs the higher deductible for anyone with predictable medical needs and enough cash flow to absorb a bad year.
Understanding the inputs
Monthly contribution should include anything your employer puts in, which commonly runs $500 to $1,500 a year and counts toward the same IRS limit. Note that this calculator does not enforce that limit, so check your entry against the $4,300 or $8,550 cap plus the $1,000 catch-up if you are 55 or older.
Expected return should reflect how the balance is actually invested. If it is sitting in the default cash sweep, the honest input is under 1 percent, not 7. Annual expenses should represent the medical costs you expect to face in retirement, which is the figure the projected balance ultimately has to cover.
How is this calculated?
FV = PV(1+r)^n + PMT×[(1+r)^n − 1]/r. HSAs offer triple tax advantages: pre-tax contributions, tax-free growth, and tax-free withdrawals for medical expenses.
A worked example
A 35-year-old with $8,000 in an HSA, contributing $600 a month at 7 percent, reaches roughly $797,000 by age 65. Contributions across those 30 years total $224,000, so around $573,000 of that balance is growth that has never been taxed and, if spent on qualified medical costs, never will be.
Compare that with spending most of it along the way and investing only $200 a month: the balance at 65 falls to about $309,000. Nearly half a million dollars separates the two approaches, and the only behavioral difference is paying routine medical bills from regular income instead of the account.
Limitations and assumptions
This is a projection under fixed assumptions, not a prediction. It applies a constant return every year with no volatility, so it cannot show sequence-of-returns risk, and it does not enforce annual contribution limits, model the loss of eligibility at Medicare enrolment, or account for the cash balance most providers require before you may invest.
It also treats medical expenses as a single annual figure when real healthcare costs are lumpy and unpredictable, and it excludes long-term care, which is the largest uninsured risk most retirees face. Read the projection as an argument for a strategy rather than a forecast of a balance.
Common Questions
- What makes an HSA different from other accounts?
- It is the only account with three tax advantages at once: contributions reduce taxable income, growth is untaxed, and withdrawals for qualified medical expenses are tax-free. A 401(k) taxes you on the way out and a Roth taxes you on the way in. An HSA used for medical costs is never taxed at all.
- How much can I contribute in 2025?
- The limits are $4,300 for self-only coverage and $8,550 for family coverage, plus a $1,000 catch-up contribution from age 55. Contributions made through payroll also avoid FICA, which a direct contribution does not, so funding through your employer is worth roughly 7.65 percent more.
- Do I need a specific health plan to qualify?
- Yes. You must be covered by a qualifying high deductible health plan, which for 2025 means a minimum deductible of $1,650 for self-only or $3,300 for family cover, with out-of-pocket maximums capped at $8,300 and $16,600. Being enrolled in Medicare or claimed as a dependent disqualifies you.
- Should I invest the balance or leave it in cash?
- Most HSAs sit entirely in cash earning almost nothing, which forfeits the middle tax advantage. If you can pay current medical costs from your regular budget, invest the balance above whatever cash cushion your provider requires. That decision is the difference between an HSA as a spending account and as a retirement account.
- Can I pay myself back for old medical bills?
- Yes, and this is the most underused feature. There is no deadline for reimbursement, so you can pay a $3,000 expense from your checking account today, keep the receipt, leave the HSA invested for twenty years, and reimburse yourself tax-free later. Keep documentation, because the burden of proof is yours.
- What happens to my HSA at 65?
- The 20 percent penalty on non-medical withdrawals disappears, so it behaves like a Traditional IRA for anything other than healthcare and stays entirely tax-free for medical costs. You can also use it for Medicare Part B, Part D and Advantage premiums, though not for Medigap.
- How much healthcare will I actually need to fund?
- Fidelity's annual estimate puts lifetime healthcare costs for a single 65-year-old retiring today at roughly $165,000, excluding long-term care. That figure covers premiums, copays and out-of-pocket costs across retirement. A well-funded HSA can cover a substantial share of it entirely tax-free.
- Can I still contribute once I am on Medicare?
- No. Enrolling in any part of Medicare ends HSA eligibility, and Part A enrolment can be backdated up to six months, which creates an easy trap for people working past 65. Stop contributions at least six months before enrolling to avoid an excess contribution penalty.
- What happens to the account when I die?
- A spouse beneficiary inherits it as their own HSA with all the tax benefits intact. Any other beneficiary receives it as fully taxable income in the year of death, with no ability to spread it. That difference makes beneficiary designation more consequential on an HSA than on most accounts.