Medicare Supplement (Medigap) Calculator

Medigap (Medicare Supplement) fills the gaps in Original Medicare — Part A hospital deductible ($1,632 in 2026), Part B 20% coinsurance, and excess charges. Plan G is the most popular modern Medigap plan; Plan N is ~30% cheaper but adds a $20 office copay and $50 ER copay, plus you pay the Part B deductible ($240) yourself.

Real example. 67-year-old female in Ohio. Plan G: $165/month ($1,980/year) + Part B deductible $240 = $2,220 total. Plan N: $120/month ($1,440/year) + Part B deductible $240 + (8 doctor visits × $20 copay) = $1,840 total. Plan N saves $380/year — AS LONG AS she doesn't need to see specialists who don't accept Medicare assignment (those trigger excess charges Plan N doesn't cover). If she visits the doctor 20 times (chronic condition): Plan N costs $2,080, only $140 cheaper.

Shop during your Medigap Open Enrollment window — the 6 months starting the first of the month you turn 65 and enroll in Part B. After that window, carriers can medically underwrite you in most states and may decline or rate you up. Plan G and Plan N are the two to compare; high-deductible Plan G is a budget alternative for healthy seniors.

If you want to stress-test the answer, pair with health insurance total cost calculator and HMO vs. PPO comparison — the two numbers should corroborate each other within ~15%. If they don't, one of your inputs is off.

Mistakes: waiting past the 6-month open enrollment window and discovering you can't change plans later; confusing Medicare Advantage (replacement for Original Medicare) with Medigap (supplement to Original Medicare) — they are mutually exclusive; picking Plan F (now closed to new enrollees after 2020); switching carriers after age 70 without realizing you'll be underwritten and may be denied.

Medigap rates are set by three methods: attained age (goes up every birthday — most common), issue age (set at enrollment — rises with inflation, not age), or community rated (same for everyone in state). Attained-age policies look cheap at 65 and become expensive at 80; issue-age and community-rated cost more upfront but are flatter. Tobacco, BMI, and household discount (both spouses same carrier) all apply.

Connecticut, Massachusetts, Maine, and New York have continuous open enrollment or guaranteed issue for Medigap — you can switch plans at any time without underwriting. California and Oregon allow a "birthday rule" — 30-day window each year to switch to equal or lesser coverage without underwriting.

Before you pull quotes, write a one-page spec: exact limits, exact deductible, exact riders, exact coverage period. Give all carriers the same spec. When quotes come back, ignore the headline premium and normalize — is the deductible identical, are the riders identical, is the liability limit identical? Only then compare.

Drop each carrier's real number back into this calculator to see the expected annual cost (premium + deductible × claim probability), not just the sticker. A $150 cheaper premium with a $750 higher deductible is usually worse once you account for probability. Pair with long-term care insurance calculator and hospital indemnity calculator to confirm you're sizing limits correctly.

Shop Medigap every 2 years even if rates are stable. If your health is still good, you can switch carriers without penalty in guaranteed-issue states or during your birthday window. If you become uninsurable, you're locked in but at least you have the coverage.

Calendar a reminder for 45 days before the renewal. Pull three fresh quotes — one from a direct writer (GEICO, Progressive), one from a captive agent (State Farm, Allstate, Farmers), and one from an independent agent who represents 8–12 carriers. Combine with critical illness calculator for your full portfolio view.

This tool is educational, not financial or insurance advice. Actual premiums depend on factors no web tool can perfectly model, including carrier-specific underwriting, state regulations, your individual history, and policy-form details. Formulas here use simplified national averages to get you within a reasonable planning range — not to produce a bindable quote. Before purchasing any Medicare supplement policy, consult a licensed insurance agent in your state. Carrier links on this page are sponsored affiliate placements; we may earn a commission if you click and purchase, at no additional cost to you. This does not influence the calculator math or our editorial picks.

This calculator runs entirely in your browser using JavaScript. Nothing you type is transmitted to our servers. Nothing is stored after you close the tab. Use the Export PDF button to take the inputs and results with you. If you want a Medicare supplement feature that doesn't exist yet, send a note via the contact page — we prioritize tool-building based on real user requests.