How to Compare Mortgage Offers the Right Way
When you're comparing mortgage offers, it's tempting to focus on just the headline interest rate. But that's like judging a car by its top speed and ignoring fuel consumption, insurance, and maintenance costs. The right way to compare mortgage offers means looking at total cost, fees, flexibility, and what happens if your circumstances change.
This guide walks you through the numbers you actually need to evaluate—with real examples so you can apply them to your own situation.
What Really Matters When Comparing Mortgages
The interest rate is important, but it's just one piece of the puzzle. Here's what actually drives whether one mortgage offer costs you less than another.
Loan-to-value (LTV) is the single biggest factor in the rate you'll get. LTV is your mortgage as a percentage of the property's value—so a £200,000 mortgage on a £250,000 property is an 80% LTV.
A 60% LTV (40% deposit) typically gets rates 0.5–1% lower than a 90% LTV (10% deposit). On a £250,000 mortgage over 25 years, that 0.5% difference means roughly £50–100 less per month. Over the whole mortgage, you're looking at £15,000–£30,000 in total interest savings.
Fixed vs. variable rates come down to certainty versus flexibility. A fixed rate locks in your payment for 2–5 years (sometimes longer), protecting you if the Bank of England base rate rises. Variable rates—tracker mortgages or standard variable rate (SVR)—move with the base rate. When rates fall, your payment drops. When they rise, it hurts.
In 2026, five-year fixed rates sit around [STAT NEEDED: current 5-year fixed average], which is currently cheaper than SVR for most borrowers. But the "right" choice depends on whether you can afford a rate rise and how long you plan to stay in the property.
Repayment vs. interest-only changes your monthly outgoing dramatically and determines whether you actually own your home at the end of the mortgage.
- A £200,000 repayment mortgage over 25 years at 4.5% costs around £1,111 per month. At the end, you own the house outright.
- Interest-only on the same deal is just £750 per month. But you still owe the full £200,000 at the end. You need a separate plan to pay it back—a pension, investment pot, or sale proceeds.
Use our mortgage calculator to run these scenarios with your actual numbers. The calculator shows you monthly payment, total interest paid, and total cost over the lifetime of the loan.
The Interest Rate Isn't the Whole Story: All the Other Costs
Most borrowers focus on the interest rate and miss the fact that total cost includes arrangement fees, surveys, stamp duty, insurance, and legal fees.
Arrangement fees (also called product fees) range from £0 to £2,500. A lender offering 4.1% with a £1,500 fee is often more expensive than 4.3% with no fee, especially on shorter fixes. You have to calculate the total interest paid over the fix period and add the fee to see the true cost.
Valuation and survey costs £250–£600 depending on property price and survey type. Your lender will require a valuation (usually £300–400). A homebuyer's report (around £400–600) is optional but strongly recommended—it flags structural issues before you're committed to the purchase. A full structural survey (£600–1,500) is worth doing on older properties.
Solicitor and conveyancer fees run £800–£1,500 plus disbursements (Land Registry searches, local authority searches, etc.). Get quotes from at least three firms. Don't automatically go with your lender's panel conveyancer—they sometimes charge more.
Stamp Duty Land Tax is payable when you buy. For England (rates differ slightly in Scotland, Wales, Northern Ireland):
- First-time buyers: £0 on purchases up to £425,000
- Other buyers: £0 on the first £125,000, then 2% up to £250,000, 5% up to £925,000, 10% up to £1.5 million, 12% above that
On a £250,000 property as a first-time buyer, you pay zero. On a £450,000 property as a first-time buyer, you pay 5% on the £25,000 above £425,000—that's £1,250.
Buildings insurance is mandatory—your lender won't complete the mortgage without proof of it. Expect £300–600 per year depending on property value and location. Get quotes before you commit to a lender; some charge more than others.
Mortgage protection insurance (life insurance) isn't required but is strongly recommended if you have dependents. A 25-year £250,000 level term policy for a healthy 35-year-old costs roughly £15–25 per month. If something happens to you, your family isn't left with a mortgage they can't afford.
The Numbers Game: How to Calculate Total Cost
Let's work through a real example. Say you're comparing three mortgage offers for a £200,000 loan over 25 years.
Offer A: 4.5% fixed for 5 years, no arrangement fee
- Monthly payment: £1,111
- Total interest over 5 years: £13,393
- Arrangement fee: £0
- Total cost over 5 years: £13,393
Offer B: 4.3% fixed for 5 years, £999 arrangement fee
- Monthly payment: £1,071
- Total interest over 5 years: £12,805
- Arrangement fee: £999
- Total cost over 5 years: £13,804
In this case, Offer A is cheaper despite the higher rate—you save £411 over 5 years. The monthly payment is higher (£40), but you don't pay the fee. This is why rate isn't everything.
Offer C: 4.1% fixed for 5 years, £1,500 arrangement fee
- Monthly payment: £1,030
- Total interest over 5 years: £12,216
- Arrangement fee: £1,500
- Total cost over 5 years: £13,716
Now Offer A looks even better. Offer C has the lowest rate but the highest total cost because of the fee.
Of course, this math changes once you look beyond 5 years. If you're staying for 10+ years, a lower rate matters more and fees matter less. That's why you need to think about your own timeline—how long do you plan to stay in the house?
(Yes, mortgages are famous for making maths everyone has to do. The calculator handles this so you don't have to—plug in the numbers and it shows you the answer.)
Early Repayment Charges and the Cost of Flexibility
Here's something many borrowers miss: early repayment charges (ERCs). If you pay off the mortgage early—or remortgage—during your fixed-rate period, your lender charges you a penalty. It's typically 1–5% of the outstanding balance.
On a £200,000 mortgage, a 3% ERC is £6,000. That's a huge hit if you weren't expecting it.
Some lenders offer mortgages with no ERC or a lower one. You pay for this flexibility—the rate is typically 0.2–0.3% higher. Again, you need to decide whether the flexibility is worth it to you. If you're planning to move or remortgage within 5 years, paying 0.2% more for no ERC might be the smarter choice.
Common Mistakes That Cost Thousands
Not shopping around. The difference between the best and worst mortgage deal can be £150–250 per month. Use a whole-of-market mortgage broker or compare at least 5 lenders directly. Check your credit score first—it affects the rates you'll be offered.
Ignoring affordability caps. Just because a lender will offer you 4.5× your salary doesn't mean you should borrow that much. Stress-test your budget: What happens if rates rise 2%? What if one income drops? Use our mortgage affordability calculator to find a number that actually works for your life, not just on paper.
Forgetting about your deposit. A larger deposit gets you a better rate—but only if you can actually afford it without wiping out your savings. A 15% deposit (85% LTV) costs about 0.3–0.4% more than 20% (80% LTV), but it leaves you with an emergency fund. The slightly higher rate is often worth it. Read about deposit amounts here.
Comparing only the headline rate. We've covered this, but it's worth repeating: always calculate total cost over the period you'll actually stay in the house. A 2-year fix at 3.9% with a £999 fee is different from a 5-year fix at 4.2% with no fee. You can't know which is better without doing the maths—use the mortgage calculator to compare scenarios.
Not understanding your mortgage statement. Once you've chosen and completed your mortgage, know how to read your statement. It tells you how much principal you've paid down, how much interest you've paid, and what's left. This helps you spot whether overpayments are actually reducing your mortgage or just sitting in an offset account.
What to Ask Your Lender (Or Broker)
When you're reviewing offers, always ask:
- What's the total cost of borrowing including all fees? Not just the interest rate.
- What happens when my fixed rate ends? Will I automatically move to SVR, or do I remortgage? At what rate?
- Can I overpay? Most lenders let you overpay up to 10% per year penalty-free. Overpaying reduces the term and total interest paid.
- What's the early repayment charge? If there's an ERC, ask whether a higher rate gets you one with no penalty.
- Do you offer a porting option? If you're moving, can you take the mortgage with you to the new property instead of remortgaging?
Frequently Asked Questions
Q: What's the best time to fix my mortgage? A: When you're confident you can afford the payment if rates rise. That sounds backwards, but it's the test. A fixed rate is insurance against rate rises; you pay for that insurance by accepting a rate that's higher than SVR today. If you can't afford the fixed rate, don't take it.
Q: Do I need a mortgage broker, or should I go direct to lenders? A: Brokers can shop whole-of-market (all lenders) and often get exclusive rates that aren't available direct. But they take a commission, which lenders sometimes absorb. If you're confident comparing mortgages yourself, direct is fine. If you're unsure, a broker can save you time and often money.
Q: What if I want to overpay my mortgage? A: Most lenders allow overpayments up to 10% of the outstanding balance per year, penalty-free. Overpaying reduces your mortgage term and saves you interest. Our amortisation guide explains how this works.
Q: Should I fix for 2, 3, 5, or 10 years? A: Longer fixes (5–10 years) lock in certainty but usually cost 0.3–0.6% more than 2–3 year fixes. Choose based on your timeline and risk tolerance. If you're planning to move in 3 years, a 5-year fix with an ERC might cost you if rates fall and you remortgage.
Q: How does stamp duty affect my total cost? A: Stamp duty is a one-time cost at purchase, not ongoing. For a first-time buyer under £425,000, it's £0. For others, it's 2–12% of the purchase price above thresholds. Budget for it upfront—it's not part of the mortgage, but it's part of buying a home.
Q: What counts as income on my mortgage application? A: Salary, bonuses, commissions, self-employment income (usually averaged over 2–3 years), rental income, and in some cases, benefits. Lenders are stricter on variable income—they'll average it or stress-test it downward.
Q: Is remortgaging worth it? A: If rates have fallen or your LTV has improved (you've paid down the mortgage), remortgaging can save you money. But factor in the costs—valuation, arrangement fees, legal fees. Savings need to exceed the costs within your timeframe.
Q: What if I can't get approved for the rate quoted? A: Rates are typically offered based on credit score, income, LTV, and employment history. If you're declined or offered a worse rate, ask why. Improve your credit score, increase your deposit, or choose a lender with more flexible criteria.
Next Steps
The best way to understand your options is to plug your actual numbers into our mortgage calculator. Try different deposit amounts, rates, and terms to see how each variable affects your monthly payment and total cost.
If you're a first-time buyer, check your affordability using your actual salary and savings. If you already have a mortgage, calculate whether remortgaging could save you money—many homeowners overpay by staying on their lender's SVR after their fix ends.
The mortgage that costs you the least isn't always the one with the lowest headline rate. It's the one where you've done the maths across the full term, understood the fees, understood your flexibility options, and stress-tested your budget. That's how to compare mortgage offers the right way.