About Mortgage FV Calculator

By Knobugsoft Engineering · Knobugsoft LLC · Last reviewed August 14, 2026 · Methodology

Mortgage FV Calculator exists because most mortgage calculators stop at the monthly payment. A mortgage is a thirty-year cash-flow instrument, and the questions that actually matter — should I overpay, refinance, recast, rent instead, or invest the difference — can only be answered with the same tools an analyst would use on any other long-dated asset: amortisation schedules, net present value, internal rate of return and future value.

Who publishes this site

The site is built and operated by Knobugsoft LLC, a US-registered software company that builds quantitative financial tools, including an options and futures analytics platform. The same in-house calculation service that powers those products powers the amortisation, time-value-of-money and refinance maths on this site. Editorial and product decisions are made by the Knobugsoft team; we are not a lender, a broker, or a mortgage originator, and we do not arrange or fund loans.

What the site does

• Full PITI modelling. Principal, interest, property tax, homeowners insurance, PMI and HOA dues in one payment figure, with PMI dropping off at the correct loan-to-value thresholds rather than running for the whole term.
• Investment metrics. Net present value, internal rate of return and future value on the full cash-flow series, with the discount rate defaulting to the live 10-year US Treasury yield so the comparison is against a real risk-free alternative.
• Decision comparisons. rent versus buy, 15 versus 30 year terms, refinance break-even, recasting and overpayment scenarios, each computed on the same engine so the numbers are directly comparable.
• Exports and integrations. Every schedule can be exported to Excel or PDF, embedded in another site as a widget, or called programmatically through the public API.

Who it is for

Three audiences use the site heavily. Home buyers who want to know the true carrying cost of a specific house rather than a headline payment. Owners deciding what to do with spare cash — overpay, recast, refinance or invest. And real estate and finance professionals who embed the calculator on their own sites or pull schedules through the API for client-facing reports.

How the numbers are produced

No figures on this site are estimated or approximated in the browser. Every payment, schedule row, NPV, IRR and future value is computed by our calculation service using exact decimal arithmetic, then rendered here. The methodology, formulas and assumptions behind each tool are documented on the methodology page, and the calculation results are regression-tested against a suite of worked examples on every release.

How the site is funded

The calculators are free and usable without an account. The business is funded three ways: an optional Pro subscription for saved scenarios, white-label embedding and API access; licensing and sponsorship arrangements with financial businesses; and advertising. Where a link to a lender or financial product is a paid placement, it is labelled as sponsored or an advertisement. Paid placements never change the output of a calculation, the ordering logic of a comparison table, or the editorial content of a page.

What we do not do

We do not give financial, tax, legal or mortgage advice, and nothing on the site should be read as a recommendation to take, refinance or decline any loan. We do not sell personal data. We do not publish testimonials, ratings or performance claims we cannot substantiate. Rates and cost figures shown in examples are illustrative defaults, not quotes — your lender's actual terms will differ.

Corrections and contact

If a calculation looks wrong, tell us and we will investigate it as a bug rather than a matter of opinion. Reach us through the contact page or at [email protected].