help to buy calculator

What this help to buy calculator does

If you have a Help to Buy equity loan (or want to understand how one works), you need more than a basic mortgage calculator. The monthly mortgage payment is only one piece of the picture. Your deposit, the government’s equity share, and potential future repayment amount all affect the real cost.

This calculator brings those pieces together so you can quickly estimate:

• Your cash deposit amount
• The Help to Buy equity loan amount
• The mortgage you need from a lender
• Your estimated monthly mortgage payment
• How equity-loan fees may look after the interest-free period
• What repayment could look like if property values change

A quick refresher: how Help to Buy equity loan worked

Under the Help to Buy Equity Loan scheme in England, buyers could purchase a new-build home with a small deposit and a government equity loan. The equity loan was typically up to 20% outside London and up to 40% in London (at relevant points in the scheme).

Two key mechanics matter most:

• The equity loan is a percentage of your home’s value, not a fixed repayment amount.
• When you repay, you generally repay that same percentage of the property value at the time of repayment.

So if house prices rise, the amount you repay can rise too. If prices fall, repayment can be lower.

How the calculator estimates your numbers

1) Upfront structure

The tool splits your purchase into three pieces:

• Deposit = property price × deposit %
• Equity loan = property price × equity-loan %
• Mortgage needed = property price − deposit − equity loan

2) Monthly mortgage payment

The payment uses a standard repayment mortgage formula based on loan amount, annual interest rate, and term. This gives an estimated principal-and-interest monthly payment.

3) Equity-loan fee estimate

Historically, Help to Buy equity loans were interest-free for the first five years, with fees starting in year six. This calculator estimates that fee from year six onward using:

• Base fee rate of 1.75% in year six
• Annual increase assumption (your input) for later years
• Simple monthly management fee assumption of £1

4) Future repayment scenario

If you enter expected house-price growth and years until sale/remortgage, the calculator estimates future property value and the likely equity-loan repayment amount (same share percentage of future value).

Example: why this matters

Imagine a £300,000 purchase with a 5% deposit and a 20% equity loan. Your mortgage may look comfortably smaller than buying without Help to Buy. But 8–10 years later, if the property value has increased, the equity loan repayment may be significantly larger than the original cash amount borrowed.

This does not mean the scheme is “bad” or “good” in all cases. It means you should model both short-term affordability and long-term exit cost.

Costs people often forget

• Valuation and admin costs when repaying the equity loan
• Conveyancing/legal fees for staircasing or full redemption
• Mortgage product fees when remortgaging
• Service charge/ground rent impacts (where relevant)
• Higher monthly costs when your initial fixed mortgage rate ends

How to use this calculator well

Run at least three scenarios

• Base case: modest house-price growth, current mortgage rate
• Stress case: higher mortgage rate, slower income growth
• Optimistic case: good wage growth and manageable refinance rates

Compare remortgage timing

Try “years until sale/remortgage” values like 5, 8, and 12. You may find that timing changes repayment costs and monthly affordability in ways that are not obvious at first glance.

Frequently asked questions

Is this calculator still useful now that the scheme has closed to new applicants?

Yes. Many homeowners still hold Help to Buy equity loans, and they need to model repayment decisions, remortgage options, and long-term costs.

Does this replace broker advice?

No. It is a planning tool. Your lender criteria, credit profile, product fees, legal costs, and valuation outcomes can materially change real-world numbers.

Can house prices falling reduce equity-loan repayment?

In principle, yes, because repayment is based on percentage share of value at repayment. But market movements are uncertain and should not be relied on as a strategy.

Bottom line

A good help to buy calculator should help you see the full structure, not just a monthly repayment. Use this tool to stress-test your plan, then review your numbers with a qualified mortgage adviser before making decisions.