Calculator methodology and test cases

Read the assumptions with the result

Use the units shown beside the inputs. The calculator page identifies the scenario and includes its available calculation notes and exclusions. Use the linked model below for a formula and a reproducible case where one is documented.

For fixed monthly installments, divide the annual note-rate percent by 1,200. For daily simple interest, use principal × annual rate as a decimal × days ÷ the stated day-count basis. These are different models. Verify the basis and any intermediate rounding with your lender.

FinToku checks page structure, input controls and script integrity across the catalog. The examples below document specific calculation checks. A check date records the scope of work performed and is separate from a logic change date.

For additional examples, see the loan model methodology or the calculator change and corrections log.

mortgage home loan calculator

Why we built this Separate the loan payment from the monthly cost of owning the home.

Formula For fixed monthly amortization, payment = P × r ÷ [1 − (1 + r)^(−n)]. P is principal, r is annual note-rate percent divided by 1,200, and n is the number of monthly payments. At 0% the payment is P ÷ n. The displayed housing payment adds the recurring items included in the selected scenario.

Timing and rounding Uses equal monthly periods with no daily accrual. The example retains unrounded results until display, then rounds to cents.

Worked check The CFPB fixed-rate Loan Estimate lists $761.78 per month in principal and interest for $162,000 at 3.875% over 30 years. FinToku reproduced that principal-and-interest figure. CFPB fixed-rate Loan Estimate sample.

What the estimate leaves out This check covers principal and interest. Escrow, mortgage insurance and association dues depend on the figures and terms for the specific property.

emi calculator

Why we built this See how changing the term changes the monthly payment and total interest.

Formula For fixed monthly amortization, payment = P × r ÷ [1 − (1 + r)^(−n)]. P is principal, r is annual note-rate percent divided by 1,200, and n is the number of monthly payments. At 0% the payment is P ÷ n. In flat-rate mode, monthly payment = [P + P × annual rate as a decimal × years] ÷ n.

Timing and rounding Uses equal monthly periods with no daily accrual. The example retains unrounded results until display, then rounds to cents.

Worked check The CFPB fixed-rate Loan Estimate lists $761.78 per month in principal and interest for $162,000 at 3.875% over 30 years. FinToku reproduced that principal-and-interest figure. The check used the reducing-balance option. CFPB fixed-rate Loan Estimate sample.

What the estimate leaves out Flat-rate and reducing-balance quotes use different interest bases. Daily interest and irregular payment dates require lender-specific figures.

mortgage loan estimate comparison calculator

Why we built this Compare two written fixed-rate estimates using the same time horizon.

Formula For fixed monthly amortization, payment = P × r ÷ [1 − (1 + r)^(−n)]. P is principal, r is annual note-rate percent divided by 1,200, and n is the number of monthly payments. At 0% the payment is P ÷ n. Cash to close is copied from the entered disclosure. Horizon cost is accrued interest plus entered lender charges minus lender credits plus modeled mortgage insurance. Remaining principal is reported separately.

Timing and rounding Uses equal monthly periods with no daily accrual. The example retains unrounded results until display, then rounds to cents.

Worked check The CFPB fixed-rate Loan Estimate lists $761.78 per month in principal and interest for $162,000 at 3.875% over 30 years. FinToku reproduced that principal-and-interest figure. The check isolated principal and interest in the initial housing-cost row by setting other monthly costs to zero. CFPB fixed-rate Loan Estimate sample.

What the estimate leaves out Adjustable rates, balloon payments and lender-specific escrow changes require a separate comparison.

loan refinance break even calculator

Why we built this Find out whether a smaller payment also reduces the cost of keeping the loan for your planned holding period.

Formula For fixed monthly amortization, payment = P × r ÷ [1 − (1 + r)^(−n)]. P is principal, r is annual note-rate percent divided by 1,200, and n is the number of monthly payments. At 0% the payment is P ÷ n. Cash-flow break-even is upfront cost divided by monthly savings, rounded up to a whole month. Horizon comparison includes payments and remaining principal.

Timing and rounding Uses equal monthly periods with no daily accrual. The example retains unrounded results until display, then rounds to cents.

Worked check In a 0% test, $12,000 over 12 months compared with 24 months and a $1,000 fee saves $500 a month, recovers the fee in two months, and costs $1,000 more over a six-month holding period after balances are included. CFPB refinance tradeoffs.

What the estimate leaves out A shorter break-even alone can miss a larger remaining balance. This model treats fees as paid in cash and excludes taxes and discounting.

refinance break even calculator

Why we built this Check how long it takes for the payment difference on two quotes to recover an upfront fee.

Formula Whole months to recover the fee = ceiling of fee divided by monthly savings. If savings are zero or negative, there is no cash-flow break-even.

Timing and rounding Uses the quoted monthly amounts as entered and rounds the recovery period up.

Worked check A $1,000 fee and a $500 monthly reduction give two months to recover the fee. CFPB refinance tradeoffs.

What the estimate leaves out This calculation excludes remaining balances, different payoff dates and the time value of money. Use the full refinance comparison for those questions.

debt consolidation savings calculator

Why we built this Isolate the effect of a new rate and upfront fee using the same balance and term.

Formula For fixed monthly amortization, payment = P × r ÷ [1 − (1 + r)^(−n)]. P is principal, r is annual note-rate percent divided by 1,200, and n is the number of monthly payments. At 0% the payment is P ÷ n. Modeled savings = current payment × n − new payment × n − upfront fee.

Timing and rounding Uses equal monthly periods with no daily accrual. The example retains unrounded results until display, then rounds to cents.

Worked check With a $1,200 balance, 12 months and 0% in both options, a $60 fee leaves the payment at $100 and increases total cost by $60. CFPB guide to credit card debt consolidation.

What the estimate leaves out Different card minimums, future charges, promotional rates and accounts left open require separate modeling.

loan apr with fees calculator

Why we built this Show how the same installment can have a higher borrowing cost when a fee reduces available cash.

Formula Cash received = principal − withheld fee. The modeled APR is 12 times the monthly discount rate that equates cash received to the present value of the equal installments.

Timing and rounding Uses equal monthly cash-flow periods. Displays APR to two decimals and dollars to cents.

Worked check With $1,200 principal at 0% and 12 payments, a $120 withheld fee leaves $1,080 cash and $100 monthly payments. The fee-inclusive estimate rises above zero. CFPB guidance on installment loan fees.

What the estimate leaves out Use the lender’s actual disclosure for regulatory APR. This model excludes irregular dates and only includes the entered fee.

personal loan net proceeds calculator

Why we built this Estimate how much of the loan reaches the borrower after a withheld origination fee.

Formula Fee = principal × entered percentage ÷ 100. Cash available = principal − origination fee − other withheld charges.

Timing and rounding Calculates using the entered amount and percentage, then displays dollars and cents.

Worked check A $10,000 loan with a 5% withheld fee gives a $500 fee and $9,500 in net proceeds. CFPB guidance on installment loan fees.

What the estimate leaves out The model includes other withheld charges you enter. It leaves out repayment, payments made to creditors and fees paid from outside cash.

tax calculator

Why we built this Estimate U.S. federal income tax from ordinary income and see how marginal rates apply.

Formula For the U.S. option, subtract the modeled standard deduction from ordinary gross income and floor the result at zero. Tax each remaining slice at its own marginal rate and add the slices.

Timing and rounding Calculates the bracket amounts before the interface formats the total for display.

Worked check A 2026 head-of-household scenario with $67,450 of taxable income matches $7,740 in IRS Publication 505, Schedule Z. IRS Publication 505, 2026 federal tax schedules.

What the estimate leaves out The example checks U.S. federal ordinary-income brackets. Credits, state tax, itemized deductions and special income rules may change an actual return. Other countries have separate models.

paycheck calculator

Why we built this Estimate take-home pay for a budget using a simplified annual tax model.

Formula Annualize wages and deductions, estimate federal ordinary-income tax using bracket slices, then deduct modeled payroll taxes and entered state, local and benefit amounts. Divide the resulting annual net pay by pay periods.

Timing and rounding Uses annual figures before dividing by pay periods and formatting the result.

Worked check With the 2026 head-of-household standard deduction and no credits, $225,900 annual wages produce $201,750 taxable income and $39,207 in modeled federal income tax, matching IRS Schedule Z. IRS Publication 505, 2026 federal tax schedules.

What the estimate leaves out Actual withholding depends on Form W-4, the payroll method and year-to-date wages. State and local rates are estimates or user inputs. Use IRS Publication 15-T for payroll withholding.

Debt payoff strategies

At each monthly step, accrue balance × APR percent ÷ 1,200. Apply minimums and put the remaining budget toward the highest-rate debt for avalanche or lowest-balance debt for snowball. Keep full precision for the model and display results rounded to cents.

At 0% with $600 owed and $100 paid monthly, six payments clear the debt. The model assumes fixed APRs, no new charges, and payments made once a month.

Small-business scenarios

Business tools use the input period and units shown beside each formula. The industry selection changes illustrative defaults, and results are formatted for display.