How Is Bridging Loan Interest Calculated in the UK?

The first thing that trips people up is the format itself. Bridging loan interest is quoted monthly, not annually, a habit that makes sense once you understand why, these are short-term products, often running just months rather than years, so pricing per month reflects the timeframe far more usefully than an annual percentage would.

Bank of England held base rate at 4.25% in June 2026 - waiting for inflation to cool.

73% of UK SMEs expect to grow in the next 12 months - confidence remains strong.

Step one: understand the monthly rate

A bridging loan might be quoted at, say, 0.75% per month. That figure applies to the loan balance each month it’s outstanding, rather than being an annual rate divided down. To compare it against something more familiar, multiply by 12, 0.75% per month works out to roughly 9% on an annualised basis, considerably higher than a standard mortgage, reflecting the premium paid for speed and short-term flexibility.

Step two: identify how the interest is structured

This is where bridging loans genuinely differ from a standard mortgage, since there are three common ways interest can be handled:

Retained interest

The lender calculates the total interest expected over the agreed loan term upfront, and deducts that amount from the loan itself at the start. You don’t make monthly payments, because the interest has already been accounted for within the facility. If you repay early, some lenders will refund a portion of the retained interest for the unused period, though this varies by lender.

Rolled-up interest

Rather than being calculated and set aside at the outset, interest accumulates month by month throughout the loan, added to the running balance. Nothing is paid during the term, the full accrued interest, alongside the original loan, is repaid together at the end.

Serviced interest

Interest is paid monthly, as it would be with a standard mortgage, rather than being retained or rolled up. This structure is typically only available on regulated bridging loans, and requires the borrower to demonstrate they can afford the monthly payments alongside their other outgoings.

Step three: work out the actual monthly cost

Take the loan amount and multiply it by the monthly rate. For example, on a £300,000 loan at 0.75% per month, the monthly interest cost would be £2,250. Under a rolled-up structure, this figure would be added to the balance each month, meaning the following month’s interest is then calculated against a slightly larger sum, so costs compound gradually over the term rather than staying static.

Step four: factor in the loan term

Because interest is charged monthly, the total cost scales directly with how long the loan runs. A facility charging £2,250 a month in interest costs considerably more if it runs for 12 months than if it’s repaid within 4, which is exactly why bridging finance is generally intended for short-term use, and why an unnecessarily extended term can quietly become expensive.

Step five: add the other costs on top

Interest is rarely the only cost. Most bridging loans also involve:

• Arrangement fees, typically around 2% of the loan amount
• Valuation fees
• Legal fees, for both the lender’s and your own solicitor
• Exit fees, with some lenders, though not all charge these

None of these are captured by the headline monthly rate alone, which is why comparing bridging quotes purely on the percentage figure can be misleading without looking at the full cost picture.

Does the interest structure affect the total amount you actually pay?

Not dramatically in principle, since retained, rolled-up, and serviced interest are broadly different ways of timing the same underlying cost, rather than fundamentally different prices. That said, the practical difference matters for cash flow, retained and rolled-up structures mean no monthly outgoings during the term, useful if you’re managing a renovation or waiting on a sale, while serviced interest suits borrowers who’d rather pay as they go and reduce the amount owed at the end.

Can you calculate this yourself before approaching a lender?

Yes, and it’s worth doing before you commit to anything. Money Pilot’s open-source calculator and guides let borrowers model the total cost of a bridging facility, monthly interest, arrangement fees, and the overall figure across different potential loan terms, before ever submitting an application, giving a realistic picture of what a specific deal will actually cost rather than relying on a headline rate alone.

What happens if you repay early?

Depending on the lender and the interest structure, repaying before the end of the agreed term can sometimes reduce the total interest owed, particularly under a rolled-up structure, since less time has accrued interest. Retained interest arrangements vary more by lender, some refund unused interest, others don’t, so it’s worth checking this specifically before signing anything if an early exit is a realistic possibility.

The mistake borrowers often make

Some borrowers focus purely on the monthly percentage rate when comparing bridging quotes, without properly calculating the total cost across the likely term, including arrangement fees and how the specific interest structure, retained, rolled-up, or serviced, actually affects cash flow and the final amount owed. A slightly lower monthly rate with a longer minimum term or higher fees can end up costing more overall than a marginally higher rate with better all-round terms.

The bottom line

Bridging loan interest is calculated monthly, applied against the loan balance, and structured as retained, rolled-up, or serviced depending on the lender and product. Understanding which structure applies, and calculating the full cost across your expected term rather than judging the headline rate alone, is essential before comparing quotes properly. Money Pilot’s open-source calculator and guides let borrowers work through this calculation directly, turning a monthly percentage into a genuine, comparable total cost figure before committing to any specific facility.