Every money calculation you need — take-home pay, mortgage payments, loan costs, investment growth, retirement projections, and business finance. All free, all instant, all verified against current IRS and Federal Reserve data. No signup on any page.
Finance calculators translate the math behind money decisions into immediate answers. You enter the numbers that describe your situation — your salary, your loan amount, your interest rate — and the calculator applies a verified formula to return the exact figure you need. No spreadsheet, no guesswork, no financial advisor required for the calculation itself.
The most used tool in this category is the paycheck calculator. Most people assume gross pay minus a flat percentage gives their take-home pay. That is wrong. The actual calculation layers four separate withholdings: federal income tax (which uses graduated brackets, not a flat rate), Social Security (6.2% flat up to the wage base), Medicare (1.45% with an additional 0.9% surtax on income above $200,000), and state income tax (which varies from 0% in Texas and Florida to 13.3% in California). Miss any one of those and your budget is off.
A mortgage payment has four components: principal, interest, property taxes, and homeowners insurance — known collectively as PITI. Most free calculators online show only principal and interest, which understates the true monthly cost by $300 to $800 depending on location and loan size. A $400,000 home with a 6.5% rate on a 30-year loan has a principal-and-interest payment of $2,528. Add Texas property taxes at roughly 1.7% ($567/month) and a basic insurance premium ($150/month) and the real payment is $3,245 — 28% higher than what an incomplete mortgage calculator would show.
The PMI trap nobody warns about: If your down payment is under 20%, lenders require Private Mortgage Insurance (PMI), typically 0.5% to 1.5% of the loan amount annually. On a $350,000 loan, that adds $146 to $438 per month on top of PITI. PMI cancels automatically once your loan balance drops to 80% of the home's original appraised value — you do not have to refinance to get rid of it.
Here is the example that makes this concrete. $10,000 invested at 7% annual return does not double in 14 years — it nearly doubles in 10 (to $19,672) and grows to $76,123 in 30 years. The formula is A = P(1 + r/n)^(nt), where P is principal, r is the annual rate as a decimal, n is compounding periods per year, and t is years. Run these numbers through the compound interest calculator and try adjusting the start date by 10 years — the difference is more striking than most people expect.
The most common mistake people make with compound interest is waiting. Starting at 25 vs 35 with the same monthly contribution does not produce twice the retirement balance — it produces three to four times more, because the earliest contributions compound the longest. No finance calculator can fix the decision not to start; they can only show you what the delay costs.
The table below shows approximate annual and biweekly take-home pay for a single filer with no pre-tax deductions in Texas (no state income tax). Add your state tax to get a closer estimate for your location.
| Gross Salary | Federal Tax Est. | FICA Est. | Net Annual (TX) | Biweekly Check |
|---|---|---|---|---|
| $40,000 | $3,388 | $3,060 | $33,552 | $1,290 |
| $55,000 | $5,788 | $4,208 | $45,004 | $1,731 |
| $70,000 | $8,580 | $5,355 | $56,065 | $2,156 |
| $90,000 | $13,468 | $6,885 | $69,647 | $2,679 |
| $120,000 | $21,468 | $9,180 | $89,352 | $3,437 |
| $150,000 | $30,168 | $11,480 | $108,352 | $4,167 |
California residents subtract an additional 6–13% for state income tax. New York City residents subtract roughly 9–10% combined state and city tax on top of federal. These estimates use 2026 IRS withholding tables and assume standard W-4 with no additional withholding adjustments.
Monthly P&I payment at 6.5% on a 30-year fixed mortgage. Remember to add property tax and insurance for the true PITI payment — the table below shows principal and interest only.
| Loan Amount | Monthly P&I | Total Paid (30yr) | Total Interest |
|---|---|---|---|
| $200,000 | $1,264 | $455,040 | $255,040 |
| $300,000 | $1,896 | $682,560 | $382,560 |
| $400,000 | $2,528 | $910,080 | $510,080 |
| $500,000 | $3,160 | $1,137,600 | $637,600 |
| $600,000 | $3,792 | $1,365,120 | $765,120 |
| $750,000 | $4,740 | $1,706,400 | $956,400 |
What people underestimate about mortgages: On a $400,000 loan at 6.5% you pay $510,080 in interest over 30 years — more than the original loan amount. Making one extra payment per year reduces the payoff timeline by roughly 4 years and saves over $70,000 in interest. The mortgage refinance calculator shows exactly when refinancing to a lower rate breaks even against the closing costs.
Most first-year freelancers miss the self-employment tax entirely because their previous employer paid the employer half of FICA invisibly. When you work for yourself, you pay both sides — 15.3% total up to the $176,100 Social Security wage base, then 2.9% Medicare above that. On $80,000 net self-employment income the total SE tax is $11,304. You deduct half ($5,652) from gross income before calculating federal income tax, which reduces the income tax burden slightly but does not eliminate it. The self-employment tax calculator handles this deduction automatically so your quarterly estimate is accurate.
Use the paycheck calculator by state. Enter gross pay, pay frequency, filing status, and any pre-tax deductions like 401(k) contributions and health insurance. The result is your exact net pay. If it does not match your actual paycheck, the most common culprits are supplemental pay withholding (which uses a flat 22% federal rate), incorrect W-4 allowances, or a state where the calculator needs a specific local tax code input.
Start with the self-employment tax calculator. Run it quarterly before estimated tax payments are due — April 15, June 16, September 15, and January 15 of the following year. Then use the net income figure it produces as the input for the federal income tax calculator. Most self-employed people who receive a large tax bill in April are either skipping quarterly payments or using gross revenue instead of net profit as their income figure.
Run three calculators in sequence. Start with the home affordability calculator to get your ceiling. Then use the mortgage calculator with PITI to verify the real monthly payment fits your budget. Finally, if you are considering refinancing, the mortgage refinance calculator shows your break-even month. If break-even is under 24 months and you plan to stay in the home longer than that, refinancing almost always makes sense assuming you can qualify at the new rate.
The markup calculator and margin calculator are used more often than anything else in this group because the difference between markup and margin is genuinely confusing and consistently misapplied. A product that costs $40 sold at $60 has a 50% markup but a 33% margin. If you are pricing to hit a 40% gross margin, you need a 67% markup — not a 40% markup. Getting this wrong means every product you sell is underpriced, and the business is bleeding money it cannot see on the income statement until the end of the year.
The Stripe fee calculation most sellers miss: On small transactions, the $0.30 flat component of Stripe's 2.9% + $0.30 fee becomes disproportionately expensive. A $10 transaction has an effective Stripe rate of 5.9%. A $5 transaction costs 8.9% in fees. If your product is priced below $20, the flat fee component is eating more margin than the percentage component. Use the Stripe fee calculator to find the exact net for any transaction size and build that cost into your pricing.
The 401(k) calculator and compound interest calculator work best together. Run the compound interest calculator first on your current balance and planned contribution to see what trajectory you are on. Then use the 401(k) calculator to test different contribution percentages and see how each change affects both your projected balance and your current take-home pay. The tradeoff between retirement savings and current income is the most personal calculation in personal finance, and no generic advice covers it — you need your specific numbers.
Most used tools across all 14 categories