Medicare Calculators & Tools
Fifteen free calculators for eligibility, costs, IRMAA, plan comparisons, enrollment timing, savings programs, and coverage before you turn 65, using official CMS and Medicare.gov data.
Medicare has four parts, several enrollment windows with penalties for missing them, and a market of private plans on top of the public program. Most questions come down to three things: whether you are enrolled correctly and on time, what it will cost, and which route fits you, Original Medicare with a Medigap policy or a Medicare Advantage plan.
Am I Eligible, and Am I Enrolling on Time?
Most people become eligible at 65, but being eligible is not the same as being enrolled on time. If you miss your Initial Enrollment Period, the seven months around your 65th birthday, you can owe a late enrollment penalty that is added to your premium for as long as you have the coverage. If you are still working and have employer coverage, you may be able to delay without a penalty, depending on the size of the employer and the type of plan. Start with the Medicare Eligibility Checker and the Enrollment Period Finder to confirm your windows, and use the Late Enrollment Penalty Calculator if you think you have missed one. If you already have Medicare, the AEP Countdown shows how many days are left to change plans this year.
Original Medicare vs. Medicare Advantage vs. Medigap
Original Medicare (Parts A and B) is run by the federal government and accepted by any provider in the country that takes Medicare. It has gaps: no yearly limit on out-of-pocket costs, 20% coinsurance on most Part B services, and no routine dental, vision or hearing coverage. People fill those gaps in one of two ways. The first is a private Medigap (Medicare Supplement) policy alongside Original Medicare. The second is a Medicare Advantage (Part C) plan, which adds extra benefits and usually drug coverage but uses a provider network. You cannot have both. Our Medicare Advantage vs Original Medicare comparison and Medigap Plan Comparison Tool set out the trade-offs side by side.
What Will This Cost?
Premiums, deductibles and coinsurance change every year. Higher earners also pay IRMAA, a surcharge on Part B and Part D based on income from two years earlier. It rises in steps, so one dollar over a threshold brings the full surcharge for that tier. The Medicare Cost Calculator and IRMAA Calculator use current official figures to estimate your premium. If you take several prescriptions, the Part D Coverage Gap Calculator shows when you would reach the yearly out-of-pocket cap, and the Part D Plan Comparison Guide explains how drug plans differ before you shop. If you are considering a Roth conversion, the Roth Conversion IRMAA Planner shows whether it would move you into a higher IRMAA tier.
Help If Money Is Tight
Medicare has programs for people with limited income and resources, and many who qualify never apply. Medicare Savings Programs (QMB, SLMB and QI) can pay the Part B premium and sometimes deductibles and coinsurance. Extra Help (the Low-Income Subsidy) lowers Part D drug costs. Check both with the Medicare Savings Program Eligibility Calculator and the Extra Help Eligibility Calculator. If you also qualify for Medicaid, the PACE Program Eligibility Checker and our Prescription Savings Finder cover more sources of help.
Not Yet on Medicare? The Coverage Gap Before 65
If you retire or lose employer coverage before 65, you need health insurance until Medicare starts, and that comes from a different system. The ACA Subsidy Calculator estimates your Marketplace premium tax credit for those years, including the income cutoff for subsidies that returned in 2026. Your income in those years affects how much help you get, so check it before you decide when to retire or claim Social Security.
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What's the difference between Original Medicare and Medicare Advantage?
Original Medicare (Part A and Part B) is run directly by the federal government and lets you see any provider that accepts Medicare nationwide. Medicare Advantage (Part C) is a private-plan alternative that usually bundles in Part D drug coverage and extra benefits, but typically uses a network and requires referrals.
What happens if I miss my Initial Enrollment Period?
You may owe a late enrollment penalty that is added to your Part B or Part D premium for as long as you have the coverage, and you may have to wait for the next General Enrollment Period to sign up. The exception is a Special Enrollment Period, most often because you had coverage through an employer.
Do I need a Medigap plan if I have Original Medicare?
Not required, but Original Medicare alone leaves you responsible for deductibles, coinsurance, and 20% of most Part B costs with no annual cap. A Medigap policy covers some or most of that gap. It cannot be paired with Medicare Advantage.
What is IRMAA and who has to pay it?
IRMAA (Income-Related Monthly Adjustment Amount) is a surcharge added to Part B and Part D premiums for higher-income beneficiaries, based on your tax return from two years prior. Most beneficiaries never hit the income threshold and pay the standard premium.
This page is for general educational purposes and is not affiliated with Medicare.gov or CMS. The figures in our calculators come from official CMS publications. See our Data Sources page for details.