Not financial advice. Mortgage FV Calculator is a software calculator, not a personal-finance product or advisory service. It computes standard financial functions and displays the results for your convenience. Nothing here constitutes, or is intended to constitute, financial, investment, tax, legal, mortgage, credit, or insurance advice. Always consult a qualified professional before making any financial decision.
Scenario guides
By Knobugsoft Engineering · Knobugsoft LLC · Last reviewed August 14, 2026 · Methodology
A calculator answers the question you type in. These guides show the question worth asking — each one takes a real housing decision, states every assumption, works the numbers through, and says plainly where the answer flips.
- First-time buyer putting 5% downA worked scenario for a first-time buyer with 5% down: real PITI including PMI, when PMI drops off, cash needed at closing, and the break-even against renting.Buyers with limited savings deciding whether to buy now or save toward 20%.
- Pay the mortgage off early or invest the differenceA side-by-side scenario comparing extra mortgage principal against investing the same money, including tax treatment, risk and the interest actually saved.Owners with surplus cash flow deciding where the marginal dollar goes.
- Refinancing after rates fallA scenario showing the true break-even on a refinance: closing costs, term reset, cumulative interest and how long you must stay for the switch to pay.Owners holding an above-market rate weighing a refinance.
- Buying a first rental propertyA full scenario for a first rental purchase: financed cash flow, cap rate, cash-on-cash return, vacancy and maintenance reserves, and levered IRR on exit.Investors evaluating a first single-family or small multifamily rental.
- Buying when you will move in three yearsA short-horizon scenario showing why transaction costs, not interest rates, decide whether buying beats renting when you expect to move within a few years.Buyers with a known short holding period — relocation, training programmes, military moves.
- Choosing a 15-year term over a 30-yearA scenario comparing a 15-year mortgage against a 30-year loan with the payment difference invested, including flexibility, tax treatment and total cost.Buyers choosing a term at origination who can afford either payment.
- 30-year vs 15-year when inflation runs at 5%How 5% inflation changes the 15-vs-30-year decision: the real value of fixed payments, the real cost of interest, and why the nominal interest saving overstates the 15-year advantage.Buyers choosing a term in a high-inflation environment, and anyone deciding whether cheap fixed debt is worth keeping.
- Is buying worth it at a 7% mortgage rate? An NPV answerA discounted cash-flow answer to buying at 7%: net present value, IRR, the appreciation rate the deal needs to break even, and how long you must stay for the maths to work.Buyers weighing a purchase at current rates against continuing to rent and invest.
- Mortgage recast vs extra principal: which does more with a lump sumWhat a lump sum does to your mortgage depending on whether you recast or simply overpay: lower payment versus shorter term, interest saved, and which suits which situation.Owners with a bonus, inheritance or sale proceeds deciding how to apply it to an existing mortgage.
About the author
Quantitative finance engineering team, Knobugsoft LLC
Knobugsoft LLC builds financial calculation software. The same amortisation, time-value-of-money and discounted cash-flow engine that powers these guides serves the site's public API and is covered by an automated regression test suite run on every release.
- • Amortisation and escrow modelling (principal, interest, taxes, insurance, PMI, HOA)
- • Time value of money: future value, present value, NPV and IRR
- • Rent-versus-buy and refinance break-even analysis
Every formula used on this site is documented on the methodology page. Spotted something wrong? Tell us — corrections are published with the review date updated.