Mortgage Deposits: 5% vs 10% vs 15% vs 25% — How Much Difference Does It Actually Make? (UK Guide)

The deposit you put down doesn't just determine how much you need to save — it shapes which mortgage deals you can access, how your monthly repayment compares, and how much room you have if your circumstances change. This guide explains what your deposit percentage does in loan-to-value terms, compares 5%, 10%, 15% and 25% deposits side by side, and looks at what a bigger deposit changes — and what it doesn't.

What your deposit percentage actually means

Your deposit and mortgage together add up to 100% of the purchase price. The mortgage portion is the loan-to-value, or LTV — a 5% deposit means 95% LTV, 10% means 90% LTV, and so on. The smaller your deposit, the higher your LTV, and the more risk the lender takes on, which affects which deals you can access and the rate offered. On a £280,000 property: 5% deposit = £14,000, £266,000 mortgage (95% LTV); 10% = £28,000, £252,000 (90% LTV); 15% = £42,000, £238,000 (85% LTV); 25% = £70,000, £210,000 (75% LTV).

Side by side

The cheapest deals are typically reserved for 40%+ deposits (60% LTV or below) — even 25% deposit is past the steepest part of the pricing curve, not the bottom of it.

Does a bigger deposit get you a cheaper rate?

Generally yes — lower LTV means lower risk, so average rates usually step down as deposit rises. The size of that gap varies constantly with market conditions, so treat figures as a snapshot, not a prediction. For context only: Moneyfacts data from January 2026 showed average two-year fixed rates of roughly 4.3% at 60% LTV against roughly 4.5% at 75% LTV. These are illustrative figures from a single month, not current rates — always compare live deals.

Monthly repayment — a worked example

On that same £280,000 property, 25-year term, at an illustrative example rate of 5% (chosen purely for comparison, not a current or recommended rate): 5% deposit (£266,000 mortgage) ≈ £1,555/month; 10% (£252,000) ≈ £1,475; 15% (£238,000) ≈ £1,390; 25% (£210,000) ≈ £1,230. That's roughly £325/month difference between 5% and 25% deposit here alone, before any rate difference each deposit size might unlock. Illustration only — your own quote depends on the actual rate, term and lender.

What a bigger deposit does not change

It doesn't reduce stamp duty, which is based on purchase price. Stamp Duty for First Time Buyers UK: What You'll Actually Pay in 2026.

It doesn't replace the affordability assessment — income, outgoings and credit history are checked regardless. How Much Can You Borrow for a Mortgage? UK Income Multiples Explained (2026).

And it doesn't guarantee approval.

If you've only got a 5% deposit

95% LTV mortgages are available from mainstream lenders, and the Freedom to Buy scheme — launched 2025 as a permanent replacement for the Mortgage Guarantee Scheme — backs 95% LTV lending from participating lenders. First-Time Buyer Schemes UK Compared: Which One Actually Helps You Buy Sooner? (2026) covers this alongside the Lifetime ISA, Shared Ownership and First Homes. Rules and participating lenders change, so check current terms.

Mistakes people make with their deposit

Using every last penny and leaving nothing for costs afterwards. First-Time Buyer Moving Costs — The Real UK Numbers for 2026 breaks down what else to budget for. Assuming deposit size alone sets the rate — income and credit history matter too. Not asking early about the extra paperwork a gifted deposit needs, which can delay things near exchange.

The bottom line

A bigger deposit generally means lower LTV, more deals, and often a cheaper rate with a lower monthly repayment. But it doesn't change stamp duty, doesn't replace the affordability check, and isn't the only thing deciding your rate. A mortgage broker or regulated adviser can confirm what you'd qualify for.

This guide is general information, not financial advice.