Mortgauger

On the use of this instrument

Build a scenario for each mortgage you are weighing. Pin them side by side and let the figures speak.

Master scenario · remortgage

Where you stand today

Your current property value, what you still owe, and how long is left on the term. Use the ↦ Remortgage button on any purchase scenario to fast-forward to a specific year's balance and pre-fill these fields automatically.

— scenarios BoE · 3.75%

№ I · The Property

Current value £ Outstanding balance £

№ II · Term

Years remaining years

Loan-to-value —

№ III · Repayment

Repayment Int.-only Part&part Offset

Repayment share %

Offset savings £

№ IV · Overpayments

Fixed £ Percent %

Max each month £

Above monthly cost %

Lump sum at start £

№ V · Fee Handling

Product fee

Add to loan Pay upfront

On a remortgage there's no stamp duty or new deposit — just the lender's product fee. Adding it to the loan pushes your LTV up a touch.

Folio II

The Comparison Dashboard

Short term, long term, and every cell in between. Best figures in oxblood; worst in muted ink.

A Stress Test

What if the Bank Rate climbs after your fix ends? Add to every scenario's revert rate and watch the line bend.

Rate shock +0.00 pp

Monthly outgoings, year by year

The step shows the moment your fix expires. The taller the step, the bigger the shock.

Balance remaining

How quickly the debt shrinks. Flat lines are interest-only.

Cumulative cost over time

Total paid out by year. The line that ends lowest wins — usually.

A Glossary

Plain words for the figures above

Every term used on this page, defined in one sentence each. Skim the column relevant to where you are stuck.

The structure

Loan-to-value (LTV): Your loan as a percentage of the property's value. Lenders price in discrete tiers (60, 75, 80, 85, 90, 95%); crossing a tier changes your rate.
Initial period: The years your headline rate is locked, typically 2 or 5. When it expires you fall onto the lender's revert rate unless you remortgage.
Revert rate (SVR): The Standard Variable Rate you pay after your fix ends. Usually 2–4 points above headline rates — by design, to nudge you to remortgage.
Tier breakpoint: The point where adding a little more deposit drops you into a better LTV tier and a materially lower rate.

The types

Capital repayment: Every monthly payment covers interest plus a slice of principal. By the end of the term, the loan is gone.
Interest-only: Each month you pay only the interest; the principal remains until you repay it in a lump (usually by selling or remortgaging).
Offset: Your savings balance offsets the loan for interest calculations. You still owe the full loan, but you pay less interest each month.
Part & part: A hybrid. A portion of the loan is capital repayment; the rest is interest-only. Useful when you only expect to repay part by term end.

The costs

Stamp Duty (SDLT): A purchase tax on residential property in England & NI, banded by price. First-time buyer relief applies up to £500,000; additional-property buyers pay a 5% surcharge on every band.
Product fee: A one-off lender fee (often £999), the price of the rate you've been quoted. Pay it upfront or add it to the loan.
Cash at completion: All the money you need on day one: deposit + SDLT + any upfront fees. The bank doesn't lend this — it has to come from you.
BoE Bank Rate: The base rate set monthly by the Bank of England's Monetary Policy Committee. Trackers move with it directly; fixes are influenced indirectly via swap rates.

The strategy

Overpayments (fixed): A set £ amount paid above the required monthly cost. Reduces both total interest and term length. Most lenders allow up to 10% of the balance per year without penalty.
Overpayments (percent): Paying X% on top of each month's required cost. Scales automatically as the payment changes — for example, when the fix ends and the payment jumps.
Rate shock: The stress-test slider in the dashboard. Adds (or subtracts) points to every scenario's revert rate, so you can see what a 2pp rise after your fix would cost you.
True cost of owning: Deposit + SDLT + upfront fees + every monthly payment + any residual still owed at term end. The full bill, not just the headline payment.

Common ground