FC
FinCalc
MORTGAGE·[email protected]%$2,847/mo
CAGR·2019→202614.2%
FIRE·SAVINGS 32%18.4 yrs
CC PAYOFF·MIN PMT9.1 yrs
401(K)·EMPLOYER 4%$1.42M
DTI RATIO28%
XIRR·IRREGULAR CF11.7%
BURN RATE·RUNWAY7.2 mo
RENT VS BUY·B/E YR6
SIP·STEP-UP 10%$981K
MORTGAGE·[email protected]%$2,847/mo
CAGR·2019→202614.2%
FIRE·SAVINGS 32%18.4 yrs
CC PAYOFF·MIN PMT9.1 yrs
401(K)·EMPLOYER 4%$1.42M
DTI RATIO28%
XIRR·IRREGULAR CF11.7%
BURN RATE·RUNWAY7.2 mo
RENT VS BUY·B/E YR6
SIP·STEP-UP 10%$981K
65 guides · updated 2026

The Journal

Practical, honest guides on the math behind money decisions — loans, investing, retirement, and everything in between.

All Personal Finance Investing Business Tools
Investing
FC

12 Free Financial Calculators Worth Bookmarking in 2026

No signup, no paywall. Twelve free calculators for loans, retirement, investing, and the big life decisions, grouped by what they actually help you decide.

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How to Calculate After-Tax Cash Flow (With a Worked Example)

Cash flow tells you what moved. After-tax cash flow tells you what you actually keep. Here's the real formula and where it gets tricky.

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How to Forecast SaaS Revenue (Without Guessing)

A single-line revenue forecast is a guess in a spreadsheet. Here's how to build a real bear, base, and bull case from four inputs.

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Why Your Credit Card Minimum Payment Never Seems to Go Down

Minimum payments are designed to keep your account current, not pay it off. Here's the math behind why it takes so long — and the fix.

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When Should You Claim Social Security? 62 vs. 67 vs. 70

The age you claim Social Security permanently changes your benefit. Here's the real math behind early claiming, delaying, and the breakeven point.

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Should You Refinance Your Mortgage? The Break-Even Math

A lower rate isn't automatically a win. Here's how to calculate the real break-even point on refinancing closing costs — and where it can backfire.

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Options Trading Basics: What Breakeven Actually Means

Call, put, long, short — the payoff at expiration follows fixed rules. Here's the actual math behind breakeven, max profit, and max loss.

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Why Splitting the Bill Evenly Is Usually Unfair

An even split feels simple, but it quietly overcharges whoever ordered less. Here's the case for itemized splitting, and how to handle shared items and tip fairly.

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The Beginner's Guide to Budgeting That Actually Works

Most budgets fail within a month. Here's a simpler approach built around a few numbers you actually track.

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How to Build Financial Discipline When Motivation Isn't Enough

Willpower runs out. The financial habits that actually stick are usually the ones designed to not need it.

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5 Goal-Planning Mistakes That Quietly Sabotage Your Finances

Setting a financial goal is easy. Setting one that survives contact with an actual month is harder.

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Why Self-Employed Workers Need a Bigger Emergency Fund

Irregular income changes the math on how much cash buffer you actually need — usually more than the standard advice.

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Saving vs Investing: How to Know Which One You Need Right Now

The right answer depends on your timeline, not which one has the better return — here's how to tell the two apart.

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SMART Financial Goals: How to Set Goals You'll Actually Hit

Vague goals like "save more" rarely work. Here's how to turn them into specific, measurable targets you can actually track.

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How to Actually Improve Your Financial Health

Financial health isn't just your income — it's savings rate, debt levels, and emergency preparedness working together.

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How to Run Your Own Annual Financial Review

A once-a-year checklist to catch problems early, celebrate progress, and reset your goals for the year ahead.

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6 Common Financial Mistakes That Quietly Cost the Most

Most financial damage doesn't come from one bad decision — it comes from a handful of ordinary mistakes repeated for years.

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How Much Money Do You Need to Retire at 40?

Retiring at 40 means your money needs to last 50+ years — the math is different from a traditional retirement.

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How Much Should You Save Monthly for Retirement?

The right monthly number depends on your target date and current savings — not a flat percentage rule.

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How Much EMI Can You Actually Afford?

Lenders will approve more than you should comfortably take on — here's how to set your own real limit.

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EMI Mistakes First-Time Borrowers Make

Common, avoidable errors that turn a manageable loan into a financial strain.

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How Banks Calculate Your Loan Eligibility

Understanding the actual formula lenders use can help you improve your eligibility before applying.

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First-Time Home Buyer Guide: What the Math Actually Looks Like

Beyond the down payment — the full financial picture first-time buyers often underestimate.

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Does Prepaying a Loan Affect Your Credit Score?

The honest, nuanced answer — it's rarely as simple as 'good' or 'bad'.

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The Loan Closure Process Explained

What actually happens between your final payment and truly being done with a loan.

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Loan Foreclosure Explained: What It Means and How to Avoid It

Understanding the process — and the warning signs worth acting on long before it happens.

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The Psychological Effects of Debt — And Why the Math Alone Rarely Helps

Debt stress is a genuine, well-documented mental health factor — not just a spreadsheet problem.

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Good Debt vs. Bad Debt: A Genuinely Useful Framework

Not all debt is created equal — here's how to actually tell the difference.

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The Power of Reinvesting Dividends: A Long-Term Growth Case Study

Taking dividends as cash feels good today — reinvesting them can mean a dramatically larger portfolio decades from now.

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ETFs vs Individual Stocks: Building a Diversified Portfolio

The diversification math behind why most long-term investors are better served by funds than stock-picking.

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PEG Ratio: The Metric That Tells You If a 'Cheap' Stock Is Actually Cheap

A low P/E can be a value trap — PEG adjusts for growth to give a fairer picture.

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EV/EBITDA vs P/E: Which Valuation Multiple Should You Trust?

Two companies with identical P/E ratios can have very different real valuations once debt is factored in.

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How to Price Your Product: Margin, Markup, and Break-Even

Three numbers every small business owner needs to actually understand before setting a price.

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SaaS Revenue Forecasting: Bear, Base, and Bull Scenarios Explained

A single revenue projection number is usually a red flag — here's why ranges matter more.

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US Federal Tax Brackets Explained: Why Your Effective Rate Isn't Your Bracket

Being in the 24% bracket doesn't mean you pay 24% on all your income — here's how marginal rates actually work.

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15-Year vs 30-Year Mortgage: The Real Trade-Off

Lower total interest vs. lower monthly payment — the right choice depends on what you'd do with the difference.

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The Power of Starting Early: Compound Interest Explained

A 25-year-old and a 35-year-old saving the same amount monthly end up in very different places — here's the math.

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What's Your Financial Health Score? The 5 Numbers That Matter

A single score that sums up your overall financial position — here's what actually goes into it.

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How Much House Can You Actually Afford in 2026?

The bank's pre-approval number and your real comfortable budget are usually not the same thing.

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DCF Valuation Explained: How to Value a Stock Like an Analyst

The core idea behind discounted cash flow analysis, without the spreadsheet overwhelm.

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SIP vs Lump Sum: Which Investment Strategy Actually Wins?

The honest answer depends on market timing luck more than most SIP advocates admit.

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The Hidden Cost of Loan Processing Fees — A Side-by-Side Comparison

The lowest interest rate isn't always the cheapest loan once you account for fees.

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How Big Should Your Emergency Fund Really Be?

The generic "3-6 months" rule needs adjusting based on your actual job stability and expenses.

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Startup Burn Rate: How Many Months of Runway Do You Actually Have?

The math founders should be checking monthly, not just when a fundraise is approaching.

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Rental Property Cash Flow: Cap Rate vs Cash-on-Cash Return Explained

Two different metrics that answer two different questions about the same property.

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Equity Dilution 101: What Happens to Your Shares After Each Funding Round

A smaller slice of a bigger pie can still be worth more — here's the actual math.

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Retirement Withdrawal Rates: Is 4% Still Safe in 2026?

The famous rule was built on decades-old data — here's what's changed and what hasn't.

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New vs Used Car Loans: The Real Cost Difference Beyond the Sticker Price

Lower interest rates on new cars don't always beat the math on a used car loan.

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The Best Investments for FIRE: Where Early Retirees Actually Put Their Money

Index funds, tax-advantaged accounts, and the unglamorous asset mix behind most successful FIRE portfolios.

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FIRE in the US: The Tax-Advantaged Accounts That Shape Early Retirement

401(k) limits, the age-59½ penalty problem, and how US tax rules shape early-retirement strategy.

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FIRE in Europe: How Early Retirement Math Changes Across Borders

There's no single 'European' FIRE system — tax treatment, account rules, and safety nets vary by country.

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FIRE in Asia: Lower Costs, Different Safety Nets, and What Changes the Math

From Singapore's CPF to lower costs of living across the region — how FIRE math shifts across Asia.

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Mutual Funds for Retirement: Picking the Right Type for Each Stage of Life

Index funds, target-date funds, and bond funds serve very different jobs in a retirement portfolio.

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Retirement Planning by Age: What to Prioritize in Your 20s, 30s, 40s, 50s, and 60s

The right retirement move changes by decade — from earliest compounding to distribution planning.

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7 Common Savings Mistakes That Quietly Cost People the Most

Small, repeated mistakes — not one big blowup — are usually what derails long-term savings.

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The Real Math Behind FIRE: How to Calculate Your Retirement Number

Why the 4% rule is a starting point, not your personal answer — and the actual formula for your FIRE number.

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CAGR vs. Average Return: Why Your Investment App Is Lying to You

The two numbers look similar but tell very different stories — here's the actual math and why it matters.

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Should You Pay Off Debt or Invest First? The Actual Math

It's not about willpower or feelings — it's a comparison between your debt's interest rate and your expected investment return.

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Stock Splits Explained: Why a 4-for-1 Split Doesn't Make You Richer

A stock split doesn't create or destroy a single dollar of value. Here's what actually changes — and why the market reacts anyway.

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Why the Exchange Rate You See Online Isn't the Rate You Get

The mid-market rate on Google isn't what your bank or card charges you. Here's where the difference goes.

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Premium vs. Deductible: The Health Insurance Math Nobody Explains

The cheapest monthly premium is often the most expensive plan. Here's how to actually compare health insurance costs.

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The Real Cost of Sending Money Abroad (It's Not the Fee)

The advertised transfer fee is often the smallest cost. The exchange rate markup is where providers actually make money.

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How Much Life Insurance Do You Actually Need?

Income replacement, debt payoff, and future expenses — the three numbers that determine your real coverage need.