NatWest Mortgage Calculator UK
Calculate your monthly repayments, total interest costs, and loan-to-value ratio instantly
Your Mortgage Details
Your Results
How to Use This Calculator
Follow these steps to estimate your mortgage repayments accurately:
- Enter the total value of the property you wish to purchase or remortgage
- Input your available deposit amount (typically 5-40% of property value)
- The mortgage amount will calculate automatically by subtracting your deposit from the property value
- Enter the annual interest rate offered by your lender (check current NatWest rates or your mortgage offer)
- Select your preferred mortgage term (the number of years to repay)
- Choose between capital repayment (paying off the loan gradually) or interest-only (paying interest only, with capital due at term end)
- Add any arrangement, booking, or valuation fees, and choose whether to add these to your loan or pay upfront
- Click ‘Calculate Repayments’ to see your monthly payment, total interest, and overall costs
Calculation Methodology
The calculator uses standard UK mortgage formulas to compute your repayments:
Capital Repayment Mortgage
For repayment mortgages, we use the amortisation formula that accounts for both principal and interest:
Monthly Payment Formula:
de>M = P × [r(1 + r)^n] / [(1 + r)^n – 1]Where:
M = Monthly payment
P = Principal loan amount
r = Monthly interest rate (annual rate ÷ 12)
n = Total number of payments (years × 12)
This method distributes the loan repayment across the entire term, with early payments weighted towards interest and later payments reducing the principal more significantly.
Interest-Only Mortgage
For interest-only mortgages, the calculation is simpler:
Monthly Payment Formula:
de>M = (P × r) / 12The principal amount remains unchanged and must be repaid in full at the end of the mortgage term through alternative means (savings, investments, property sale).
Loan-to-Value (LTV) Ratio
LTV is calculated as:
Lower LTV ratios typically qualify for better interest rates as they represent lower risk to lenders. Most UK lenders offer their best rates at 60% LTV or below.
Repayment vs Interest-Only: Which Should You Choose?
| Feature | Capital Repayment | Interest-Only |
|---|---|---|
| Monthly Payments | Higher (includes principal + interest) | Lower (interest only) |
| Loan Balance | Decreases over time | Remains unchanged |
| Total Interest Paid | Lower overall | Higher overall |
| End of Term | Mortgage fully paid off | Full loan amount still owed |
| Risk Level | Lower risk | Higher risk (need repayment plan) |
| Suitable For | Most homebuyers, long-term security | Buy-to-let, property investors, short-term |
Factors Affecting Your Mortgage Rate
- Loan-to-Value Ratio: Lower LTV ratios (larger deposits) typically secure better interest rates. Rates improve significantly at 90%, 80%, 75%, and 60% LTV thresholds
- Credit Score: A higher credit score demonstrates reliability and can qualify you for preferential rates. Check your credit report before applying
- Employment Status: Employed, self-employed, or contract workers may face different lending criteria. Permanent employment generally receives more favourable terms
- Income Level: Higher and more stable income allows borrowing of larger amounts and may access better products
- Existing Debts: Outstanding loans, credit cards, and other financial commitments affect affordability calculations
- Property Type: Standard houses typically receive better rates than flats, ex-local authority properties, or non-standard construction
- Mortgage Term: Shorter terms often have lower interest rates but higher monthly payments
- Fixed vs Variable Rate: Fixed rates offer payment certainty but may cost more initially than variable rates
Frequently Asked Questions
How much deposit do I need for a mortgage?
The minimum deposit for most UK mortgages is 5% of the property value, though 10% is more common for better rates. First-time buyers often aim for 5-10%, whilst those with larger deposits (20%+ or 40%+) benefit from significantly lower interest rates. A 20% deposit typically unlocks much more competitive mortgage products.
What is the maximum I can borrow?
UK lenders typically offer mortgages between 4 and 5.5 times your annual gross income. For example, with a £50,000 salary, you might borrow £200,000-£275,000. Joint applications combine both incomes. Lenders also assess affordability by reviewing monthly outgoings, existing debts, and living costs.
What fees are involved in getting a mortgage?
Common mortgage fees include arrangement or product fees (£0-£2,000+), booking fees (£99-£250), valuation fees (£150-£1,500 depending on property value), legal/conveyancing fees (£850-£1,500), and survey costs (£400-£1,000). Some lenders offer fee-free mortgages but often at slightly higher interest rates.
Should I fix my mortgage rate or choose a variable rate?
Fixed rates provide certainty with the same monthly payment for 2, 3, 5, or 10 years, protecting against rate rises. Variable rates (tracker or standard variable rate) fluctuate with the Bank of England base rate or lender decisions. Fixed rates suit those wanting payment security; variable rates may be cheaper initially but carry uncertainty.
Can I overpay my mortgage?
Most UK mortgages allow overpayments up to 10% of the outstanding balance per year without penalties. Overpaying reduces the loan term and total interest paid. Some mortgages offer unlimited overpayments but may charge higher initial rates. Always check your specific mortgage terms.
What happens if interest rates rise?
If you have a fixed-rate mortgage, your payments remain unchanged until the fixed period ends. Variable rate and tracker mortgages will see payments increase when the Bank of England base rate rises or your lender increases their standard variable rate. Budget for potential increases of 1-2% above your current rate.
Do I need a mortgage in principle?
A mortgage in principle (also called Agreement in Principle or Decision in Principle) shows estate agents and sellers you’re a serious buyer with verified borrowing capacity. It’s not a guarantee but strengthens your position. Most lenders provide these within 24 hours using a soft credit check that doesn’t affect your credit score.
What is stamp duty and how much will I pay?
Stamp Duty Land Tax (SDLT) in England and Northern Ireland is paid on property purchases above £250,000 (£425,000 for first-time buyers on properties up to £625,000). Rates are tiered: 0% up to threshold, then 5%, 10%, and 12% on portions above. Scotland and Wales have different systems (LBTT and LTT respectively). Use an SDLT calculator for accurate amounts.
Can I get a mortgage with bad credit?
Yes, though options may be limited and rates higher. Lenders consider the severity and timing of credit issues. Minor issues from several years ago have less impact than recent defaults or CCJs. Specialist bad credit mortgage lenders exist, and a larger deposit (25%+) improves acceptance chances. Speak with a mortgage broker specialising in adverse credit.
What is the difference between valuation and survey?
A mortgage valuation is a brief assessment confirming the property is worth the amount you’re borrowing, conducted for the lender’s benefit. A survey is more detailed, for your benefit, identifying structural issues or repairs needed. Options include Condition Reports (£400-£600), HomeBuyer Reports (£600-£900), or full Structural Surveys (£800-£1,500+). Surveys are recommended but not mandatory.
Why LTV Matters
Loan-to-Value ratio significantly impacts your mortgage rate and product availability. Here’s how different LTV bands affect your options:
- 95% LTV (5% deposit): Fewest products available, highest rates (typically 5-7%), often limited to first-time buyers or specific schemes
- 90% LTV (10% deposit): More choice, rates typically 4-5.5%, standard offering for many lenders
- 85% LTV (15% deposit): Improved rates and product range, approximately 3.8-5%
- 80% LTV (20% deposit): Good rates (3.5-4.5%) with wide product selection
- 75% LTV (25% deposit): Competitive rates (3.3-4.2%), access to most mainstream deals
- 60% LTV (40% deposit): Best rates available (3-4%), premium products, lowest risk for lenders
Each 5% reduction in LTV typically saves 0.1-0.3% on your interest rate, potentially saving thousands over the mortgage term.