Our approach

Clear math. Clear assumptions.

Sumvoro uses deterministic formulas—not AI-generated answers—to calculate your estimates. Your financial inputs stay in your browser.

Simple and Advanced

Simple starts with the core inputs. Advanced exposes additional assumptions, comparisons, and schedules. Switching views does not reset your values: changed advanced settings remain active and are listed in Simple. Scenario snapshots hold inputs and results on the current page only; reloading or leaving the page clears them. Export or print before leaving if you need a record.

Loans and mortgages

Fixed monthly payments use P × r ÷ (1 − (1 + r)⁻ⁿ), where P is principal, r is the annual contract interest rate divided by 1,200, and n is the number of months. At zero interest, payment is P ÷ n. The auto-loan balloon option subtracts the balloon’s present value from principal before calculating the recurring payment; the remaining balance is due at maturity. Extra payments can reduce that final balance and shorten repayment. Real loans may use daily interest, different payment dates, or lender-specific rounding.

Use the contract interest rate rather than fee-inclusive APR when entering fees separately. Mortgage tax and insurance estimates are annual amounts divided by twelve. Advanced adds HOA dues, mortgage insurance for an entered duration, upfront closing costs, points, and extra principal. Points do not automatically change the rate. No adjustable rates, legal PMI cancellation thresholds, or tax deductions are calculated.

Car taxes and trade-ins

The default car-payment scenario applies tax to price minus trade value, floored at zero. Advanced allows no credit or a capped credit, rebate tax treatment, taxable and non-taxable fees, and warranty, GAP, and accessories paid upfront or financed. All three add-on categories share the selected tax treatment. The trade payoff affects equity, not the trade’s assumed tax credit. These are manually entered assumptions, not verified local rules. Affordability includes optional trade equity, a trade credit, non-taxable add-ons, and a reserve deducted from the down payment.

Payoff and refinancing

Extra payments reduce principal. The payoff tool supports a one-time payment, delayed recurring extras, and a separately paid penalty. It flags debt that cannot clear within 1,200 months. Refinancing counts fees once, upfront or financed, and can include cash in or out. Horizon comparisons include payments already made plus remaining debt, adjusted for upfront cash and cash received. Break-even is the first nonnegative modeled comparison, not a promise that all later horizons save money. Unentered penalties, accrued interest, refunds, and future rate changes are excluded.

Savings projections

Defaults use nominal annual return with monthly compounding and end-of-month deposits. Advanced supports effective annual yield, beginning-of-month deposits, annual contribution increases, and inflation. A simplified tax drag applies to positive returns; annual fees are deducted proportionally each month. Fees can produce negative net growth, but market losses and changing returns are not simulated. The savings-goal tool inflates the entered target when inflation is selected and solves for the first year’s monthly contribution. Fractional years round to whole months; returns are not guaranteed.

Everyday percentages, tax, and tips

Advanced percentage tools expose alternative bases, inverse calculations, successive changes, and compounded change per period. Discounts apply sequentially before a fixed coupon. Tax supports an exempt portion and additive or compounded rates. Tips can use a before- or after-tax base and account for service charges. Monetary components round to cents; shared bills allocate leftover cents so shares add to the total. No tax rates or merchant rules are looked up automatically.

Affordability is not approval

Car affordability works backward from your payment budget after ownership costs. Home affordability uses the tighter of your housing-cost and total-debt limits, then subtracts entered non-loan housing costs. Neither model verifies income, credit, lender eligibility, available cash reserves, or property-specific costs. Treat the result as a budgeting scenario, not a lending decision.

Precision and limits

Calculations retain precision internally; displayed money is rounded. Schedules are limited to 1,200 months. Financial rates are limited to 0–100%, and individual money inputs to $1 trillion. Invalid fields hide the estimate and disable printing until corrected. Printing opens your browser’s system print dialog; the report itself uses a Sumvoro-designed layout.