refinance calculator
How to Use a Refinance Calculator
How a mortgage refinance calculator works: break-even on closing costs, and why a lower payment can cost more while a higher payment can save.
Financial learning library
Understand the math behind every calculator.
Seventy-four practical guides explain formulas, inputs, worked scenarios, limitations, and the next facts to verify—then connect directly to the matching calculator.
Browse calculatorsRefinance
1 guideBusiness
9 guidesroi calculator
How to Use an ROI Calculator
How to calculate ROI: the formula, total versus annualized return, which costs and income to include, a worked example, and the mistakes that skew results.
employee cost calculator
How to Use an Employee Cost Calculator
How an employee cost calculator works: adding taxes, benefits, equipment, amortized recruiting and overhead to salary for the true loaded hourly cost.
freelance hourly rate calculator
How to Use a Freelance Hourly Rate Calculator
How a freelance hourly rate calculator works: why your rate must be far above a salary's hourly equivalent, covering overhead, profit, and non-billable time.
pricing calculator
How to Use a Product Pricing & Margin Calculator
How a product pricing calculator works: the fully-loaded unit cost, why margin and fees come out of the price not added to cost, and checking your price.
business loan calculator
How to Use a Business Loan Calculator
How a business loan calculator works: the net cash you receive after fees, the total borrowing cost, and the debt-service coverage ratio lenders check.
employee benefits cost calculator
How to Use an Employee Benefits Cost Calculator
How a benefits cost calculator works: totaling health, retirement and PTO into benefits as a share of salary, and why paid time off is a real cost.
break-even calculator
How to Use a Break-Even Calculator
How a break-even calculator works: the contribution margin that covers fixed costs, the units to break even, and the margin of safety above it.
eor calculator
How to Use an Employer of Record Cost Calculator
How an employer-of-record cost calculator works: why EOR beats your own entity below a break-even headcount, and flips above it.
payroll cost calculator
How to Use a Payroll Cost Calculator
How a payroll cost calculator works: the employer taxes, workers' comp, benefits and admin on top of gross pay, and the employer load behind the true cost.
Mortgage
7 guidesmortgage refinance calculator
How to Use a Mortgage Refinance Savings Calculator
How a mortgage refinance calculator works: measuring savings through your expected move date, counting faster equity, not just the monthly payment change.
mortgage calculator
How to Use a Mortgage Calculator
How a mortgage calculator builds your full monthly payment: principal, interest, taxes, insurance, PMI and HOA, with worked examples and what it leaves out.
mortgage affordability calculator
How to Use a Mortgage Affordability Calculator
How a mortgage affordability calculator works: the 28/36 DTI ceiling, how PITI fills your housing budget, and why it is a lender's view that ignores your cash.
mortgage points calculator
How to Use a Mortgage Points Calculator
How a mortgage points calculator works: the break-even month where buying down the rate pays off, and why selling early loses the upfront cost.
arm calculator
How to Use an ARM Calculator
How an ARM calculator works: the fully-indexed rate you should expect at reset, the caps that limit each jump, and the lifetime-cap worst case.
va mortgage calculator
How to Use a VA Mortgage Calculator
How a VA mortgage calculator works: the funding fee that replaces PMI, how a down payment and first-vs-subsequent use change it, and who is exempt.
construction loan calculator
How to Use a Construction Loan Calculator
How a construction loan calculator works: why interest hits only the average drawn balance, how it rolls into the permanent loan, and the contingency.
Tax
8 guidesself-employed tax calculator
How to Use a Self-Employed Tax Calculator
How a self-employed tax calculator works: the 15.3% SE tax on 92.35% of profit, the half-SE deduction, and the quarterly set-aside, using 2026 figures.
capital gains tax calculator
How to Use a Capital Gains Tax Calculator
How to calculate capital gains tax for 2026: basis, short- versus long-term rates, the 0%, 15% and 20% bands, the 3.8% NIIT, and a worked example.
rental income tax calculator
How to Use a Rental Income Tax Calculator
How a rental income tax calculator works: why depreciation makes taxable income lower than cash flow, and how the tax and after-tax cash flow are figured.
bonus tax calculator
How to Use a Bonus & Severance Tax Calculator
How a bonus tax calculator works: the 22% flat supplemental withholding, why it is not your tax rate, and the Social Security and Medicare also taken out.
income tax calculator
How to Use an Income Tax Calculator
How 2026 federal income tax is calculated: the standard deduction, progressive brackets, and why your marginal rate is higher than the rate you actually pay.
paycheck calculator
How to Use a Paycheck Calculator
How a paycheck calculator works out take-home pay: federal withholding, FICA, state tax, and why a pre-tax deduction costs less than its face value.
sales tax calculator
How to Use a Sales Tax Calculator
How to calculate sales tax: the formula, how to work backwards from a total that already includes tax, and why the rate to use depends on where you are.
estate tax calculator
How to Use an Estate Tax Calculator
How an estate tax calculator works: how the exemption shelters most estates, why only the amount above it is taxed, and how prior gifts count against it.
Real Estate
8 guidesrental property roi calculator
How to Use a Rental Property ROI Calculator
How a rental property ROI calculator works: the income-to-NOI waterfall, and why cap rate and cash-on-cash return measure very different things.
rent vs buy calculator
How to Use a Rent vs. Buy Calculator
How a rent vs. buy calculator works: comparing the net cost to buy against total rent over your stay, and why time and appreciation decide the winner.
home affordability calculator
How to Use a Home Affordability Calculator
How a home affordability calculator works: the 28/36 DTI rule, why your cash on hand often caps the price before income does, and how to read the limit.
closing costs calculator
How to Use a Closing Costs Calculator
How a closing costs calculator works: the lender, third-party and prepaid buckets, and how credits and your deposit reduce the cash to close.
net proceeds calculator
How to Use a Home Sale Net Proceeds Calculator
How a home sale net proceeds calculator works: how commission, costs and the mortgage payoff cut the sale price down, and the separate capital-gain estimate.
down payment calculator
How to Use a Down Payment Calculator
How a down payment calculator works: why your cash target is more than the down payment, how closing costs and a reserve add in, and how long to save the gap.
cap rate calculator
How to Use a Cap Rate Calculator
How to calculate cap rate: the NOI formula, what counts as rental income and operating expenses, a worked example, and what drives the result.
property tax calculator
How to Use a Property Tax Calculator
How a property tax calculator works: why the tax is on assessed value, not market value, how exemptions and the millage rate apply, and the effective rate.
Insurance
5 guideslife insurance needs calculator
How to Use a Life Insurance Needs Calculator
How a life insurance needs calculator works: present-valuing income replacement, adding debts and education, and netting coverage you already have.
term life insurance calculator
How to Use a Term Life Insurance Calculator
How a term life calculator works: setting the term to your longest obligation, the low cost per $1,000, and how inflation erodes a level benefit.
home insurance calculator
How to Use a Home Insurance Calculator
How a home insurance calculator works: sizing coverage to rebuild cost not market value, the standard coverage percentages, and how the premium is built.
car insurance estimator
How to Use a Car Insurance Estimator
How a car insurance estimator works: liability plus physical-damage coverage scaled by car value, driver risk and coverage level, less a deductible discount.
disability insurance calculator
How to Use a Disability Insurance Calculator
How a disability insurance calculator works: why benefits are capped below full income, the elimination period reserve you need, and the coverage gap to close.
Student Loans
4 guidesstudent loan refinance calculator
How to Use a Student Loan Refinance Calculator
How a student loan refinance calculator works: the interest a lower rate can save, and the federal benefits you give up refinancing federal loans privately.
student loan payoff calculator
How to Use a Student Loan Payoff Calculator
How a student loan payoff calculator works: how extra payments cut the standard 10-year term, plus the federal rules the simple math leaves out.
student loan repayment calculator
How to Use a Student Loan Repayment Calculator
How a student loan repayment calculator works: how a longer term cuts the monthly payment but multiplies total interest, with the 10-year plan as the base.
income-driven repayment calculator
How to Use an Income-Driven Repayment Calculator
How an income-driven repayment calculator works: payment from discretionary income, and the negative-amortization trap where a low payment grows the balance.
Retirement
5 guidesroth ira calculator
How to Use a Roth IRA Calculator
How a Roth IRA calculator works: the 2026 contribution limit, the income phase-out that can reduce or block it, and how tax-free growth adds up.
401k calculator
How to Use a 401(k) Calculator
How a 401(k) calculator projects growth: 2026 contribution limits, how an employer match works with real numbers, and the input mistakes that skew results.
retirement calculator
How to Use a Retirement Calculator
How a retirement calculator works out what you need: the nest egg, the withdrawal rate, what Social Security covers, and what to do about a shortfall.
fire calculator
How to Use a FIRE Calculator
How a FIRE calculator finds your number (25× expenses at 4%), measures your progress, and projects the years to financial independence.
social security calculator
How to Use a Social Security Calculator
How a Social Security calculator estimates your benefit: the bend-point formula, why claiming age matters, and what a simplified estimate leaves out.
Investing
6 guidesinvestment calculator
How to Use an Investment Calculator
How an investment calculator projects growth: what contributions add, what fees quietly remove, and what the total is actually worth after inflation.
cost basis calculator
How to Use a Cost Basis Calculator
How a cost basis calculator works: blending share lots into an average basis, the basis of shares sold, and the realized gain after fees.
drip calculator
How to Use a DRIP Calculator
How a DRIP calculator projects dividend reinvestment: shares, portfolio value, and dividend income over time, with a worked example and what it leaves out.
compound interest calculator
How to Use a Compound Interest Calculator
How compound interest works: the formula, why compounding frequency matters, what regular contributions add, and how inflation changes what the total is worth.
529 calculator
How to Use a 529 College Savings Calculator
How a 529 calculator sets a realistic college-savings goal, projects your balance, and finds the monthly contribution that actually funds it.
hsa calculator
How to Use an HSA Calculator
How an HSA calculator projects tax-free growth, applies the 2026 contribution limits, and shows why an invested HSA can be a retirement account.
Loans
6 guidespersonal loan calculator
How to Use a Personal Loan Calculator
How a personal loan calculator works: the monthly payment, what an origination fee really costs, and why APR matters more than the interest rate.
simple interest calculator
How to Use a Simple Interest Calculator
How a simple interest calculator works: interest on the original principal only, the P x r x t formula, and how it diverges from compound interest over time.
loan payoff calculator
How to Use a Loan Payoff Calculator
How a loan payoff calculator works: how a recurring extra payment and a one-time lump sum each cut the time and interest, measured against your baseline.
apr calculator
How to Use an APR Calculator
How an APR calculator works: why fees push the APR above the note rate, how it is solved from the payments, and why APR is the number to compare.
rv loan calculator
How to Use an RV Loan Calculator
How an RV loan calculator works: how a long term lowers the payment but piles on interest, the balloon option, and the depreciation risk the numbers hide.
amortization calculator
How to Use an Amortization Calculator
How amortization works: why early payments are mostly interest, what your balance really is after five years, and what an extra $200 a month is worth.
Auto
4 guidesauto loan calculator
How to Use an Auto Loan Calculator
How an auto loan calculator builds the amount financed from price, tax, fees and trade-in, why a longer term costs more, and what negative equity does.
auto refinance calculator
How to Use an Auto Refinance Calculator
How an auto refinance calculator compares your loan with a new one: monthly and lifetime savings, fees, break-even time, and the longer-term trap.
car affordability calculator
How to Use a Car Affordability Calculator
How a car affordability calculator works: why insurance, fuel and upkeep come out of your budget before the loan payment, and how that sets the price.
lease vs buy calculator
How to Use a Lease vs. Buy Calculator
How a lease vs. buy calculator works: why buying's net cost counts the equity you keep, and how the resale value at the end decides which option wins.
Home Equity
5 guidesheloc calculator
How to Use a HELOC Calculator
How a HELOC calculator works: the interest-only draw period, the payment jump when repayment starts, and why the balance does not fall while you draw.
home equity loan calculator
How to Use a Home Equity Loan Calculator
How a home equity loan calculator works: the fixed lump-sum payment, why fees cut the cash you receive, and the total borrowing cost beyond interest.
home equity borrowing calculator
How to Use a Home Equity Borrowing Calculator
How a home equity borrowing calculator works: why the CLTV cap, not your gross equity, sets how much you can borrow, and when capacity is zero.
heloc vs home equity loan calculator
How to Use a HELOC vs. Home Equity Loan Calculator
How a HELOC vs. home equity loan calculator works: why it compares each on its own schedule, and why matching the time horizons is what makes it fair.
reverse mortgage calculator
How to Use a Reverse Mortgage Calculator
How a reverse mortgage calculator estimates proceeds and balance growth, why the loan balance rises over time, a worked example, and what it leaves out.
Debt
6 guidesdti calculator
How to Use a Debt-to-Income Ratio Calculator
How a debt-to-income calculator works: the front-end and back-end ratios, what counts as debt, and why your back-end limit usually caps your housing budget.
debt consolidation calculator
How to Use a Debt Consolidation Calculator
How a debt consolidation calculator works: how a lower rate saves money, how the fee and a longer term erode that saving, and when consolidating is worth it.
debt payoff calculator
How to Use a Debt Payoff Calculator
How a debt payoff calculator works: how extra payments cut both the time and the interest, why a low payment traps you, and how to read the result.
credit card payoff calculator
How to Use a Credit Card Payoff Calculator
How a credit card payoff calculator works: how long a fixed payment takes to clear a balance, the interest you pay, and why a low payment costs so much.
credit card interest calculator
How to Use a Credit Card Interest Calculator
How a credit card interest calculator works: the daily periodic rate, one cycle's interest on the average daily balance, and why a payment barely dents it.
debt snowball vs avalanche calculator
How to Use a Debt Snowball vs. Avalanche Calculator
How a snowball vs. avalanche calculator works: why avalanche costs less interest, what snowball trades for motivation, and how the model estimates the gap.