Financial math
you can verify.
30 calculators and reference pages that show every step. Every assumption stated, every default overridable. Current calculator inputs stay client-side and are excluded from analytics. Privacy details.
Paycheck Calculator
LIVEIllustrative estimate for a single filer using a flat 5% state income tax and no pre-tax deductions.
Every calculator, one place
Click a category to filter, or browse them all. Each tool shows the math behind the number.
Mortgage Payment
Monthly P&I, taxes, insurance, PMI. Full amortization.
Home Affordability
Max purchase price from income, debts, down payment.
State Tax & Housing
50-state scatter plot: property tax vs. income tax.
Compound Interest
Contributions + compound growth with yearly breakdown.
Investment Return
Growth projections with dividends, inflation, CAGR.
Savings Goal
Monthly savings needed to reach your target on time.
I Bond Rate History
Treasury rates since 1998 with an issue-date schedule.
Who Owns U.S. Stocks?
Fed DFA shares by wealth, income, and age since 1989.
S&P 500 Concentration
See how the index is divided among sectors and its biggest stocks.
Foreign Investment in U.S. Stocks
Treasury holdings, purchases, and valuation changes.
Retirement Calculator
Drawdown analysis with Social Security estimates.
401(k) Calculator
Employer match, limits, catch-up, projected balance.
Roth IRA Calculator
Roth vs. Traditional with MAGI phaseouts.
Tax Bracket
Federal brackets with effective + marginal rates.
Paycheck
Take-home after federal, state, FICA for all 50 states.
Take-Home Pay Map
Interactive 50-state map: best vs. worst states for your salary.
Capital Gains
Short/long-term rates, NII surtax, net proceeds.
Self-Employment Tax
SE tax, an annual federal estimate, and a quarterly budgeting split for freelancers.
Debt Payoff
Avalanche vs. snowball with debt-free date.
Auto Loan
Payment, total interest, amortization with trade-in.
Student Loan
Fixed plans, refinance, and limited PAYE/IBR estimate.
The data behind the calculators
Primary-source series, charted at build time. Every chart is downloadable in light and dark.
S&P 500 Return History
Every annual total return since 1928. $1,000 invested in 1980 became $192,219 by end-2025.
Inflation Time Machine
What any dollar amount from any year buys today - and how fast each era halved the value of cash.
Median New-House Price History
The 1981 median new house cost $2,832/month in 2026 dollars - more than the recent new-house estimate using Freddie Mac's August 27, 2026 6.66% average.
Tax Bracket History
The top marginal rate, 1913-2026: from 7% to 94% in 1944 to 37% today, with every major tax act.
Why PennyCalc
Built by a PE professional who models leveraged buyouts for a living. These are the tools we wish existed.
Visible Math
Core calculators expose the relevant schedules, bracket breakdowns, or year-by-year projections, with assumptions and limitations beside the result.
Your Assumptions
PMI rates, tax filing status, employer match - every default can be changed. Plug in your real numbers for real answers.
Privacy First
Current inputs and results stay in your browser and are excluded from analytics. No accounts or email capture. Read the legacy-link caveat.
Guides & References
Deep dives, worked examples, and reference tables.
Financial Glossary
50+ terms in plain English
Tax2026 Tax Brackets
Rates, deductions, worked examples
TaxTax Brackets Hub
Current year + 1913-2026 history chart
Retirement2026 401(k) Limits
Deferrals, catch-up, mega backdoor
RetirementRoth vs. Traditional IRA
Side-by-side tax math
DebtAvalanche vs. Snowball
Worked example with $47K debt
InvestingCompound Interest
Rule of 72 + growth tables
InvestingS&P 500 Time Machine
$1,000 in any year since 1928
InvestingInflation Time Machine
Any dollar amount, any year since 1913
InvestingI Bond Rate History
Fixed + inflation rates by issue date since 1998
InvestingWho Owns U.S. Stocks?
Fed ownership shares by wealth group since 1989
InvestingS&P 500 Concentration
Top stocks and sector weights through time
InvestingForeign Investment in U.S. Stocks
Separate actual buying from market appreciation
MortgageNew-House Price History
The Census median new-house sale price since 1963
IncomeHourly to Salary
$20/hr = $41,600 - and what you keep
IncomeSalary After Taxes
$50K-$200K take-home breakdowns
TaxSelf-Employment Tax
SE-tax mechanics and quarterly budgeting
Frequently Asked Questions
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Can I use PennyCalc for tax planning?
Built by people who use these tools
PennyCalc is built and reviewed by three people with backgrounds in finance, consulting, and technology. Josh, formerly at Houlihan Lokey, owns the mortgage, tax, retirement, and capital-gains tools. Jessie, formerly at McKinsey & Company, writes the paycheck, 401(k), and Roth coverage. Michael, formerly at Deloitte, handles the debt, auto-loan, and implementation side. Every tool is designed to show its inputs, assumptions, and math.
About the team