Mortgage Calculators
Buying a home is the largest financial decision most people make. Our free mortgage calculators help you understand monthly payments, total interest, what you can afford, and how overpayments save you money.
Browse by Type
Payment & Affordability
Monthly payments, what you can borrow, and total cost
Refinancing & Overpayment
Refinancing savings, overpayment impact, and extra payments
More calculators coming to this category soon.
Mortgage Glossary — Key Terms Explained
- LTV (Loan-to-Value Ratio)
- The loan amount as a percentage of the property value. LTV = Loan ÷ Property Value × 100. Lower LTV = better interest rate. Typically: 60% LTV gets best rates; above 90% LTV often requires mortgage insurance.
- Fixed Rate Mortgage
- A mortgage where the interest rate stays the same for a fixed period (e.g., 2, 3, or 5 years in the UK; 15 or 30 years in the US). Predictable payments but may miss rate cuts.
- Amortisation
- The process of paying off a mortgage through regular payments. Early payments are mostly interest; later payments are mostly principal. A 30-year mortgage at 6% sees the balance exceed the original loan until year 5 due to interest.
- PITI
- Principal, Interest, Taxes, and Insurance — the full monthly housing cost including property taxes and homeowner's insurance. Lenders assess affordability based on PITI, not just principal and interest.
- Stamp Duty / Transfer Tax
- Government tax paid when purchasing property. UK: Stamp Duty Land Tax (SDLT) — tiered above £250,000 (£425,000 for first-time buyers). US: Transfer tax varies by state, typically 0.1–2% of sale price.
Frequently Asked Questions
How much mortgage can I afford?
UK lenders typically offer 4–4.5× your annual income. US lenders use the 28/36 rule: mortgage payment ≤ 28% of gross monthly income; total debt ≤ 36%. At 5% interest over 25 years, a £200,000 mortgage costs £1,169/month. Use the affordability calculator with your actual income and debts for a personalised figure.
Should I choose a 15-year or 30-year mortgage?
A 15-year mortgage has higher monthly payments but far less total interest. $300,000 at 7%: 15-year = $2,697/month, total interest $185,460; 30-year = $1,996/month, total interest $418,960. If you can afford the higher payment, the 15-year saves $233,500 in interest.
How much does overpaying my mortgage save?
Overpaying reduces the outstanding balance, which reduces interest charged. Overpaying a £200,000 mortgage by £200/month at 5% interest saves approximately £26,000 in interest and cuts 5 years off the term. The earlier you start overpaying, the more you save.
What is mortgage remortgaging / refinancing?
Refinancing (US) or remortgaging (UK) means taking out a new mortgage to replace your existing one — usually to access a lower interest rate or change the term. Calculate the break-even point: Total savings ÷ Monthly savings = months to recoup closing costs. If you plan to stay longer than the break-even period, refinancing usually makes sense.