Best Retirement Calculators Compared (2026)

The best retirement calculator depends on what you need it to get right. For historical Monte Carlo, FIRECalc and cFIREsim run your portfolio through every actual market sequence since 1871. For tax-aware withdrawal planning with marginal brackets, capital gains stacking, and Social Security taxation, CoastIQ and Boldin are the most detailed. For comprehensive planning across estate, insurance, and what-if scenarios, Boldin covers the most variables. No tool wins on every dimension.

Most "best retirement calculator" articles rank tools by UI polish and account aggregation. Those features matter, but they don't determine whether the number on screen is right. We tested the major calculators on the four dimensions that drive output accuracy: how they handle taxes, how they model Social Security, how many income sources they can stack in a single scenario, and how their Monte Carlo is built. Below is the comparison matrix, then the honest breakdown of who wins what.

The Four Dimensions That Actually Matter

Most calculators get the headline number wrong because they oversimplify one of four things: taxes, Social Security, scenario complexity, or the Monte Carlo engine. A flat 22% effective tax rate produces a different answer than running each year's income through the actual 2025 brackets (10%, 12%, 22%, 24%, 32%, 35%, 37% per Rev. Proc. 2024-40). A flat Social Security benefit produces a different answer than applying the provisional income formula in IRS Publication 915. A single-pool portfolio produces a different answer than separately tracking Traditional, Roth, and taxable accounts with their own tax treatments.

The four dimensions:

1. Tax handling. Marginal brackets vs. flat effective rate vs. none at all. A 12% bracket retiree pays a vastly different marginal cost on an extra dollar of conversion than a flat-22% model suggests. The capital gains stacking interaction with the 0% LTCG bracket ($96,700 MFJ taxable income in 2025, Rev. Proc. 2024-40) is invisible to flat-rate tools. See why most retirement calculators get taxes wrong for the underlying math.
2. Social Security modeling. A real Social Security calculation runs your other income through the provisional income formula to determine what fraction of the benefit is taxable (0%, up to 50%, or up to 85%). Calculators that ignore this miss the "tax torpedo" — a region where the marginal tax rate on Traditional IRA withdrawals can exceed 40.7% because each $1 makes another $0.85 of Social Security taxable.
3. Scenario complexity. Can the tool model multiple income sources (W-2, pension, Roth conversions, taxable brokerage sales, Social Security at age 70, RMDs) simultaneously and apply correct tax treatment to each? Or is it one withdrawal stream from one portfolio with one effective rate?
4. Monte Carlo methodology. Historical sequence vs. parametric (mean/standard deviation draws) vs. none. And: does spending stay constant in inflation-adjusted dollars, or does the tool support variable strategies like Guyton-Klinger guardrails? Constant-spending Monte Carlo overstates failure risk because real retirees cut spending in downturns.

The Comparison Matrix

We scored eight calculators on each dimension. "Marginal brackets" means the tool applies the actual 2025 federal brackets to each layer of income; "flat effective rate" means it uses a single tax percentage. "Historical sequence" Monte Carlo replays actual market periods (e.g., 1929 cohort, 1966 cohort); "parametric" draws returns from a normal or lognormal distribution with assumed mean and standard deviation.

Calculator	Price	Tax Handling	Monte Carlo	Social Security	FIRE Features	Platform
FIRECalc	Free	None (pretax only)	Historical (1871–present)	Flat benefit, no taxation	Long horizons, custom spending models	Web
cFIREsim	Free	None (optional flat rate)	Historical + parametric	Flat benefit, no taxation	Long horizons, variable spending, 72(t) input	Web
CoastIQ	Free	Marginal brackets + capital gains stacking + SS taxation	Parametric, variable spending	Provisional income formula, claiming age modeling	Roth ladder, 72(t) SEPP, ACA subsidy, capital gains harvest	iOS
Boldin (NewRetirement)	$120/yr (Planner)	Marginal brackets, multi-source	Parametric, variable spending	Provisional income formula, claiming age scenarios	Roth conversion modeling, ACA, healthcare, estate	Web
ProjectionLab	~$80/yr	Marginal brackets	Parametric, sensitivity analysis	Provisional income formula	Roth ladder, custom income/expense events	Web
Fidelity Planning & Guidance	Free (Fidelity customer)	Flat effective rate	Parametric, basic	Flat benefit, partial taxation	None FIRE-specific	Web, Fidelity app
Vanguard Retirement Nest Egg / Digital Advisor	Free / 0.15% AUM	Flat effective rate	Parametric (Nest Egg), basic	Flat benefit	None FIRE-specific	Web
Empower (formerly Personal Capital)	Free	Flat effective rate	Parametric, basic	Flat benefit	None FIRE-specific	Web, mobile

No single tool dominates the table. FIRECalc and cFIREsim are unmatched for historical-sequence Monte Carlo and cost nothing. CoastIQ, Boldin, and ProjectionLab are the only tools that handle marginal-bracket tax math correctly. Brokerage tools (Fidelity, Vanguard, Empower) are competent baselines but use flat effective rates that misprice every bracket-sensitive decision a retiree faces.

A Worked Example: Where Tax Handling Changes the Answer

Consider a married couple, both 62, retiring in 2025 with: $1.8M Traditional IRA, $400K Roth IRA, $300K taxable brokerage (cost basis $150K), and $48K combined annual Social Security if they claim at 67. They want to spend $90,000/year (after tax, inflation-adjusted) until age 95. They want to know: how much can they convert from Traditional to Roth in the gap years between 62 and 70 without crushing their effective rate?

A flat-rate calculator using 22% will tell them their conversions cost $0.22 per dollar — so convert aggressively. A marginal-bracket calculator using Rev. Proc. 2024-40 tells a different story:

• Standard deduction (MFJ, both under 65, 2025): $30,000
• 10% bracket: $0–$23,850 taxable
• 12% bracket: $23,851–$96,950
• 22% bracket: $96,951–$206,700

With no other income before Social Security begins, this couple can convert $126,950 and stay entirely within the 12% bracket — paying roughly $11,157 in federal tax, an 8.8% blended effective rate on the conversion (not 22%). Converting an additional $50,000 pushes that slice into the 22% bracket — a marginal rate 2.5× higher than what the flat-rate tool implied.

The flat-rate tool's recommendation: "convert as much as you can comfortably afford." The marginal-bracket tool's recommendation: "convert exactly $126,950 in 2025, reassess in 2026 as brackets index." Same inputs, opposite advice. Fidelity, Vanguard, and Empower fall into the first category. CoastIQ, Boldin, and ProjectionLab fall into the second. Our Roth conversion ladder guide walks through the multi-year sequencing.

Brokerage Tools: Useful Baselines, Not Planning Engines

Brokerage calculators are best for a one-glance sanity check on whether your overall trajectory is reasonable. They pull in your real account balances (Fidelity Planning & Guidance, Empower Retirement Planner) or let you enter them manually (Vanguard Retirement Nest Egg). They run a basic parametric Monte Carlo. They give you a success probability and a recommended savings rate. For someone five years out from a traditional retirement at 65, that's enough to know if you're on track.

What they don't do: marginal bracket math, Roth conversion modeling, capital gains harvesting, ACA subsidy optimization, 72(t) SEPP distributions, or any of the strategies that move the needle in the gap years between early retirement and Social Security/Medicare. Fidelity's tool applies a flat effective tax rate and assumes you start Social Security at full retirement age. Empower's tool (the rebranded Personal Capital Retirement Planner) is similar — useful for visualizing your aggregate net worth across linked accounts, weak on tax-aware withdrawal sequencing. Use them as a second opinion; don't use them to make tax-bracket decisions.

Web Planners: Boldin and ProjectionLab Are the Tax-Accurate Options

Boldin (renamed from NewRetirement in 2024) and ProjectionLab are the two web tools that consistently get tax math right. Both apply marginal brackets, both model Social Security taxation via the provisional income formula, both let you model multi-source withdrawals with separate tax treatments per account type.

Boldin's Planner+ tier ($120/year as of 2026) is the most feature-complete retirement planning tool on the market. Beyond tax-aware withdrawals, it models healthcare (including ACA subsidies pre-65 and Medicare/IRMAA post-65), Social Security claiming scenarios with side-by-side comparison, life insurance, estate planning, and tax-efficient legacy planning. Its limitation: the depth comes with a steep input requirement — expect 60–90 minutes of data entry before the model is useful.

ProjectionLab (around $80/year) is the better fit for users who want fine-grained control over income and expense timelines. You define discrete events ("kid #2 starts college in 2030," "house paid off in 2034," "switch to Medicare in 2042") and the engine threads them through the tax model. ProjectionLab's sensitivity analysis is unusually good — it shows how a single variable change (e.g., +1% return assumption) shifts the success probability across hundreds of scenarios. Less complete than Boldin on insurance and estate, but cleaner UX for FIRE planners who want to stress-test multiple strategies.

FIRECalc and cFIREsim: The Free Historical-Sequence Standard

FIRECalc has been free since 2002 and is still the reference implementation for historical-sequence Monte Carlo. You enter a portfolio, withdrawal amount, time horizon, and asset allocation. FIRECalc runs your plan against every actual rolling period since 1871 — including the 1929 cohort, the 1966 cohort (the worst sequence in modern US history), the 1973–74 stagflation cohort. It reports the percentage of historical cycles in which your portfolio survived. This is meaningfully different from parametric Monte Carlo, which draws returns from an assumed distribution that doesn't replicate actual return clustering or correlation.

cFIREsim is the successor maintained by Lauren Boland, with broader configurability: variable withdrawal strategies (Guyton-Klinger guardrails, percentage-of-portfolio, VPW), additional income streams (Social Security, pensions, part-time work), customizable spending changes (lower in later years), and side-by-side parametric Monte Carlo if you want both methodologies. It's the tool we recommend most often for FIRE planners testing 40–50 year horizons. See our 4% rule analysis for why historical-sequence testing matters more for long horizons than for traditional 30-year retirements.

The shared weakness of both: neither models taxes well. FIRECalc has no tax handling. cFIREsim supports a single flat rate. If you want to stress-test sequence-of-returns risk, use them. If you want to optimize tax-bracket decisions, you need a marginal-bracket tool alongside.

CoastIQ: Tax-Accurate Math, iOS Only

CoastIQ is a free iOS app with 17 specialized retirement analysis tools, built around the same marginal-bracket tax engine for every tool. The relevant pieces for the comparison: marginal federal brackets (2025 values from Rev. Proc. 2024-40), state tax tables for all 50 states, capital gains stacking with the 0% LTCG bracket, Social Security taxation via the provisional income formula, Roth conversion bracket-filling, 72(t) SEPP distribution modeling, and parametric Monte Carlo with variable spending. Calculations run on-device — there's no account aggregation and no server-side data collection.

Honest limitations: iOS only (no web, no Android), no account aggregation (you enter balances manually), no estate planning, no insurance modeling, no Roth conversion comparison side-by-side across multiple scenarios (Boldin is better for that), no historical-sequence Monte Carlo (FIRECalc and cFIREsim are better for that). CoastIQ is the right tool when you want quick, tax-accurate answers to specific questions — what's my optimal Roth conversion amount, what's my 0% capital gains headroom, when should I claim Social Security given my other income. It's the wrong tool if you want one app to manage every retirement variable. Related calculators worth using: our FIRE number calculator and our Coast FIRE calculator.

How to Pick

Pick on the variable that matters most to your situation, not on overall "winner" status.

• You're 5+ years from retirement and want a baseline: Fidelity Planning & Guidance (if you're a Fidelity customer) or Empower's free Retirement Planner. Don't pay for anything yet.
• You're an early retiree planning Roth conversions, 0% capital gains harvesting, or 72(t) SEPP distributions: CoastIQ (free, iOS) or ProjectionLab (~$80/year). Both apply marginal brackets correctly.
• You want to stress-test a 40–50 year horizon against actual market history: cFIREsim (free) is the best choice. FIRECalc is the simpler alternative.
• You want one tool to model every variable — estate, insurance, healthcare, taxes, scenarios: Boldin ($120/year). Be prepared for the data entry.
• You're optimizing Social Security claiming age: Boldin or CoastIQ both model the provisional income formula correctly. See when to claim Social Security for the underlying break-even math.

Frequently Asked Questions

What is the most accurate retirement calculator?

Accuracy depends on what you're modeling. For tax-aware withdrawal planning with marginal brackets, capital gains stacking, and Social Security taxation, CoastIQ and Boldin are the most detailed. For historical-sequence Monte Carlo analysis, FIRECalc and cFIREsim use actual market history (1871–present) rather than parametric assumptions. For full financial planning with estate and insurance modeling, Boldin (formerly NewRetirement) covers the most variables. The most accurate tool is the one that models the variables that matter most to your specific situation — not the one with the prettiest interface.

What is the best free retirement calculator?

FIRECalc is the best free web-based calculator for historical-sequence Monte Carlo — it runs your portfolio against every rolling period since 1871. cFIREsim adds parametric Monte Carlo and more customization, also free. For tax-aware planning, CoastIQ is free on iOS with 17 analysis tools including marginal brackets and Social Security taxation. Fidelity's Planning & Guidance tool is free for Fidelity customers. Free tools typically lack the integrated multi-scenario modeling of paid platforms like Boldin ($120/year), but for Monte Carlo and tax math individually, free tools cover most planners' needs.

What is the best retirement calculator for FIRE?

FIRE planners need calculators that handle long time horizons (40–50 years vs. 30), Roth conversion ladders, 72(t) SEPP distributions, ACA subsidy optimization, and the gap between early retirement and Social Security/Medicare. cFIREsim and FIRECalc handle long horizons well. CoastIQ models the tax optimization strategies — Roth conversions, 0% capital gains harvesting, 72(t) — at the marginal-bracket level. Boldin covers the full planning picture including healthcare. Most brokerage calculators (Fidelity, Vanguard, Empower) assume traditional retirement at 62–67 and don't model FIRE-specific strategies.

Does Fidelity have a good retirement calculator?

Fidelity's Planning & Guidance tool is solid for traditional retirees with Fidelity accounts — it pulls in your actual balances, models Social Security, and includes basic Monte Carlo simulation. Its limitations: it uses a flat effective tax rate rather than marginal brackets, doesn't model Roth conversion optimization, and assumes traditional retirement timing. For FIRE planners or anyone doing tax-bracket optimization, you'll need a more specialized tool. Fidelity's calculator is best for a quick baseline, not for tax-bracket decisions where the marginal rate cliff between 12% and 22% changes the right answer.

Should I pay for a retirement calculator?

Pay for a calculator if you need multi-scenario planning with detailed tax modeling across strategies. Tools like Boldin ($120/year) or ProjectionLab (~$80/year) pay for themselves if they help you identify a single Roth conversion opportunity or 0% capital gains harvest — the tax savings on $126,950 of conversion done in the 12% bracket instead of the 22% bracket is roughly $12,700 per year, far exceeding any subscription. Free tools (FIRECalc, cFIREsim, CoastIQ) cover Monte Carlo and tax math well for most people. The gap between free and paid is primarily in integrated estate, insurance, and side-by-side scenario comparison.

Is Empower (formerly Personal Capital) accurate for retirement planning?

Empower's Retirement Planner is accurate for visualizing aggregate net worth and producing a baseline success probability across your linked accounts. It applies a flat effective tax rate to withdrawals and uses parametric Monte Carlo, which makes it weaker for tax-bracket optimization and long-horizon sequence-of-returns testing. It's well-suited to mid-career planners who want a free integrated dashboard and don't yet need bracket-level optimization. Once you're within 10 years of retirement and making Roth conversion decisions, pair it with a marginal-bracket tool.

What's the difference between historical and parametric Monte Carlo?

Historical-sequence Monte Carlo (FIRECalc, cFIREsim) runs your plan through actual market sequences — every rolling 30-year period from 1871 onward. Parametric Monte Carlo (Fidelity, Empower, Boldin, ProjectionLab, CoastIQ) draws returns from an assumed statistical distribution (typically lognormal) with a chosen mean and standard deviation. Historical sequences capture real return clustering and the worst-case cohorts (1929, 1966, 1973). Parametric Monte Carlo offers more flexibility (you can set your own assumptions) but can understate tail risk if the assumed distribution has thinner tails than actual market history. For long FIRE horizons, historical-sequence testing matters more.