Down Payment Calculator
How much deposit you need, what it leaves you borrowing, and the loan-to-value ratio that follows.
The deposit determines the loan-to-value ratio, and the LVR determines almost everything else about the loan: whether lenders' mortgage insurance applies, which rates you are offered, and how much scrutiny the application gets.
How the down payment calculator works
The deposit determines the loan-to-value ratio, and the LVR determines almost everything else about the loan: whether lenders' mortgage insurance applies, which rates you are offered, and how much scrutiny the application gets.
The 20% deposit is a threshold rather than a rule. Below it, most markets add a mortgage insurance premium — the name differs, the effect does not — which protects the lender, not you, and is commonly several thousand. Above it the insurance disappears entirely, which is why the last few percent of a deposit is worth more than the first few.
This works in both directions: enter a deposit to see the LVR, or a target LVR to see the deposit required.
Formula: LVR = loan / price; deposit = price − loan
Worked examples
| Inputs | Deposit needed | Note |
|---|---|---|
| A 20% deposit on 750,000 | £150,000.00 | 150,000 deposit, 80% LVR |
| Only 10% saved | £75,000.00 | 90% LVR — insurance likely |
| Working back from a deposit | £120,000.00 | 84% LVR |
FAQFrequently asked questions
How much deposit do I need?
20% avoids mortgage insurance in most markets. Many lenders accept 5% to 10% with insurance added.
What is LVR?
Loan-to-value ratio — the loan as a percentage of the property price. A 20% deposit gives 80% LVR.
What is mortgage insurance?
A premium charged above 80% LVR that protects the lender if you default. It does not protect you, and it is usually added to the loan.
Why is the last part of a deposit worth most?
Because crossing the 80% threshold removes the insurance premium entirely — a step change, not a gradual improvement.
Are transfer taxes and fees part of the deposit?
No. They are extra cash you need at settlement, which is why they are shown separately here.
Where these figures come from
- CFA Institute — Quantitative Methods: The Time Value of Money — the discounting, annuity and IRR conventions used here
- US Federal Reserve — Regulation Z (Truth in Lending), APR calculation — why APR includes fees where a nominal rate does not
- MoneyHelper (UK Government-backed) — the UK's free money guidance service
Last checked: September 2026. These are the standard textbook formulas; the conventions named are those of the CFA Institute curriculum and ISO 80000 usage.