Eight finance calculators, free to use
Free, no sign-up, and everything runs in your browser so your numbers stay private. Every engine is checked against the standard closed-form financial formulas, and how that checking works is written up in full.
Paycheck Calculator
Your salary is not your paycheck. See gross-to-net with federal brackets, Social Security, Medicare, and pre-tax 401(k) and HSA deductions.
Open calculator →Investment Calculator
See what your money becomes. Model contributions, compounding, and expected return with a live growth chart and inflation-adjusted totals.
Open calculator →Loan & Mortgage
Know the real cost of borrowing. Monthly payments, total interest, PMI, and a full amortization schedule, plus what extra payments save you.
Open calculator →Auto Lease
Understand a car lease. See how depreciation, the money factor, and residual value shape your monthly payment, due at signing, and total cost.
Open calculator →Rent vs Buy
Should you rent or buy? Compare your net worth over time for each path, including what your down payment could earn if you invested it instead.
Open calculator →Debt Payoff
Get out of debt on a plan. Compare the snowball and avalanche methods side by side and see exactly which debt to attack first.
Open calculator →Net Worth Tracker
Know where you stand. Categorize what you own and owe, check your health ratios, and save snapshots to watch your progress over time.
Open tracker →Budget Builder
Give every dollar a job. Build a 50/30/20 or zero-based budget with editable targets and a live picture of where your money goes.
Open calculator →Economics and finance you can actually poke at
The calculators above answer questions about your own money. These are different: working models of how a market, a firm, or a whole economy behaves, running from supply and demand through monopoly, tariffs and game theory to DCF valuation and retirement risk. Pull the levers yourself and watch what breaks.
Retirement
Will the money last? A thousand simulated lives instead of one smooth line, showing why the order your returns arrive in can matter more than the average.
Test a plan →DCF Valuation
Value a company the way an analyst does. Forecast the cash, build the discount rate from its parts, then see how far the answer moves when two assumptions shift.
Value a company →Run a Business
Five years to build a company. Set price, headcount, marketing and R&D each quarter against a rival who fights back, and find out what actually pays for the fixed costs.
Take the job →Supply and Demand
Drag a rent ceiling, a minimum wage, or a sales tax across the market and watch shortages, tax incidence, and deadweight loss appear on the diagram.
Open the market →Macro Policy Simulator
You run the economy. Set interest rates, spending, and taxes, then steer inflation and unemployment through shocks you do not control.
Run the economy →Bonds & Yield Curve
Price a bond, see duration and convexity checked against a full repricing, then invert the yield curve and read the forward rates hiding inside it.
Price a bond →Portfolio Diversification
The only free lunch in finance. Drag correlation and watch two risky assets combine into a portfolio safer than either one alone.
Build a portfolio →Tariffs
Who actually pays for protection? Split the cost into producer gain, government revenue, and the part that reaches nobody at all.
Set a tariff →Inequality
Where the Gini coefficient comes from, how far redistribution moves it, and two economies that score identically while looking nothing alike.
Read the curve →Game Theory Solver
Type any payoff matrix and it finds the dominant strategies, every Nash equilibrium including the mixed ones, and which outcomes waste value.
Solve a game →Production Costs
When is losing money the right call? Cost curves, the shutdown point, and where a firm's supply curve actually comes from.
Find the shutdown point →Monopoly
Why a firm with no competitors deliberately sells less than it could, and what that restraint costs everyone else.
Open the model →Externalities
Why markets overproduce pollution, and how a tax sized to the damage raises total welfare instead of destroying it.
Open the model →Comparative Advantage
A country worse at making everything still gains from trade. Set the productivity of two economies and watch both consume beyond what they could produce alone.
Open the model →Money questions, worked out rather than argued about
Most financial advice tells you what to do. These take one question people actually ask, compute the answer from the models above, and say plainly where that answer stops being reliable. Every figure is traceable to a calculator on this site.
Pay off the mortgage or invest?
Prepaying earns exactly your interest rate, guaranteed. So the break-even is one number, and at 6.5% the two paths finish $3 apart on $221,000.
Read the guide →How much house can I afford?
A lender approves you on gross income. You pay from take-home. The 28% rule is really 39% to 42% of the money that actually arrives.
Read the guide →How much do I need to retire?
25 times your spending fails about one time in four. A flat-return calculator says $2.00M; allow returns to vary and the median life ends with $725k.
Read the guide →Snowball or avalanche?
Avalanche saves $728 here, and the gap scales with how far apart your rates are. But the extra $250 a month is worth five times either method.
Read the guide →Is leasing a car throwing money away?
You pay for depreciation either way. Three routes to the same car land within $751 of each other over three years, and the answer changes in month 37.
Read the guide →All guides
Every guide in one place, each one answering a single question with numbers you can reproduce.
Browse guides →I bring aerospace-floor precision to financial analysis.
I spent nearly two years laying up composite parts bound for SpaceX rockets, the Boeing V-22, and the 737 MAX, where a misread spec is not an option. Then I earned a mathematics A.S. and an economics B.A. Now I point that same discipline at financial models: build them carefully, then check the math.
Where the precision comes from
- Performed composite layup on 25+ flight-critical components for SpaceX, the Boeing V-22 Osprey, the Boeing 737 MAX, and Porsche.
- Interpreted complex engineering drawings, ply schedules, and written work instructions where tolerances left no room for deviation.
- Worked to spec in a quality-audited production environment with strict documentation and traceability requirements.
- Contributed to process improvements that increased efficiency on the production floor.
Analysis and modeling work
- Shipped eight browser-based financial calculators covering pay, borrowing, investing, and net worth, each built on an amortization, compound-growth, or lease-pricing engine.
- Modeled a rent-versus-buy decision on net worth over time, accounting for the opportunity cost of a down payment, appreciation, equity build-up, and transaction costs.
- Every engine is validated against closed-form financial formulas, including annuity, amortization, and lease-payment derivations.
- Built with no external libraries; all calculations stay client-side so user data is never transmitted.
- Shipped fourteen interactive simulators spanning microeconomics, macro policy, international trade, and corporate finance.
- Built a discounted cash flow model with a WACC build-up from CAPM, perpetuity-growth and exit-multiple terminal values, and a sensitivity grid over discount rate and growth.
- Implemented a Monte Carlo retirement model across 1,000 paths to show sequence-of-returns risk, which a flat-return projection hides entirely.
- Verified every model against closed-form results or an independent implementation before publishing, including bond duration against numerical derivatives and tariff welfare areas against direct surplus calculations.
- Collected and analyzed CPI, shelter inflation, and wage series to identify macroeconomic trends.
- Applied regression and time-series analysis to interpret patterns and test relationships between indicators.
- Built structured datasets and dashboards to present economic insights.
- Transformed raw data into clear, actionable information for non-technical readers.
What I work with
Financial modeling
Data & analysis
Tools
Process
Training
Let's talk.
If you're hiring for financial analysis, want to build something together, or just want to talk shop about the tools and the math behind them, I'd like to hear from you.