Guides
How Much Will $500 a Month Grow to in 20 Years? (At 5%, 7%, and 10%)
How much will $500 a month grow to in 20 years? About $260,463 at a 7% return, and starting five years late costs about $102,000. Here is the full math.
15 Free Calculators — Updated for 2025
Free finance calculators,
minus the fine print
Debt payoff, Social Security, taxes, take-home pay, rent vs buy — 15 interactive calculators that run entirely in your browser. No sign-ups, no spam.
Browse by Topic
Every calculator, organized
Six categories covering every major money decision — from your first paycheck to retirement planning and everything in between.
Retirement
Social Security, RMDs, pensions, and Roth strategies.
- Social Security Break-Even Calculator
- RMD Calculator — Required Minimum Distribution
- Pension vs Lump Sum Calculator
- Backdoor Roth IRA Calculator | Estimate Your Pro-Rata Tax Before Converting
Paycheck & Work
What you earn, what you keep, and what overtime pays.
- Overtime Pay Calculator
- Hourly to Salary Calculator | Convert Your Pay in Seconds
- Take-Home Pay Calculator
Taxes
Estimate what you owe before April surprises you.
- Capital Gains Tax Calculator | Short-Term vs Long-Term Rates
- Self-Employment Tax Calculator | 1099 & Freelancer Tax Estimator
Investing
Compound growth, FIRE, and valuing future cash flows.
- Compound Interest Calculator With Monthly Contributions | See Your Money Grow
- FIRE Calculator — Financial Independence, Retire Early
- Present Value of Annuity Calculator
All Calculators
15 tools, zero paywalls
Debt Snowball vs Avalanche Calculator
Compare the debt snowball vs avalanche methods on your own balances. Free calculator shows interest saved, payoff dates, and which plan fits you.
Debt Payoff
Social Security Break-Even Calculator
Should you claim Social Security at 62, 67, or 70? Free break-even calculator compares lifetime benefits and finds your crossover age.
Retirement
RMD Calculator — Required Minimum Distribution
Calculate your required minimum distribution (RMD) by age. Free RMD calculator uses the IRS Uniform Lifetime Table, with 10-year projections.
Retirement
Overtime Pay Calculator
Calculate overtime pay at time and a half or double time. Free overtime calculator with FLSA rules and California daily overtime explained.
Paycheck & Work
Pension vs Lump Sum Calculator
Pension or lump sum? Free calculator compares the present value of monthly pension payments against your lump sum offer, with break-even analysis.
Retirement
Backdoor Roth IRA Calculator | Estimate Your Pro-Rata Tax Before Converting
Use our backdoor Roth IRA calculator to estimate pro-rata tax before you convert. Real-number examples, 2025 limits, and the mistakes that cost people money.
Retirement
Hourly to Salary Calculator | Convert Your Pay in Seconds
Convert hourly pay to annual salary instantly. $25 an hour is how much a year? See the 2,080-hour math, overtime, unpaid time off, and take-home estimates.
Paycheck & Work
Compound Interest Calculator With Monthly Contributions | See Your Money Grow
Try our compound interest calculator with monthly contributions. Real examples: what $500 a month becomes in 20 years, the rule of 72, and the cost of waiting.
Investing
Capital Gains Tax Calculator | Short-Term vs Long-Term Rates
Calculate your capital gains tax in seconds. See how short-term vs long-term rates work, the 2026 brackets, and how one extra day of holding can save thousands.
Taxes
Self-Employment Tax Calculator | 1099 & Freelancer Tax Estimator
Calculate self-employment tax on freelance and 1099 income. 15.3% on 92.35% of net earnings, the deductible half, quarterly due dates, and a real example.
Taxes
FIRE Calculator — Financial Independence, Retire Early
Use our free FIRE calculator to find your financial independence number, years to early retirement, and how savings rate changes everything.
Investing
Present Value of Annuity Calculator
Free present value of annuity calculator with the exact formula, a worked example, and ordinary annuity vs annuity due explained.
Investing
Rent vs Buy Calculator
Free rent vs buy calculator: compare unrecoverable buying costs vs rent, find your break-even year, and check the price-to-rent ratio.
Home & Auto
Auto Loan Calculator
Free auto loan calculator with trade-in, down payment, tax and fees. See your monthly payment, total interest, and the 20/4/10 rule.
Home & Auto
Take-Home Pay Calculator
Free take-home pay calculator: enter your salary and state to see federal tax, FICA, and state tax — and what actually lands in your paycheck.
Paycheck & Work
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Why CountCents
Built different, on purpose
Most financial tools are walled gardens that want your email address. We built the opposite.
Private by design
Every calculation happens in your browser. Your salary, debts, and balances are never sent to a server — or anyone else. No analytics on your inputs, ever.
Show-the-math approach
Each tool explains its formula and assumptions — IRS tables, FLSA rules, amortization math — so you can trust and verify the result yourself.
Instant answers
No sign-up walls, no PDFs to download, no "enter your email for results". Type your numbers, get your answer. Every calculator works the moment the page loads.
Guides
When you want the full story
Deep dives into the math and strategy behind each financial decision. No fluff, no affiliate pitches.
Guides
Should I Take Social Security at 62 or 70? The Break-Even Math
Should I take Social Security at 62 or 70? The break-even age is about 80. Here is who gains by claiming early, who gains by waiting, and the math behind both.
Guides
The Rent vs Buy 5% Rule: A Ten-Second Sanity Check Before You House-Hunt
The rent vs buy 5% rule: multiply a home’s price by 5%, divide by 12, and compare with rent. A $400,000 home breaks even at about $1,667 a month.