Loan Repayment Calculator

Loan Repayment Guide

What's the difference between APR and Flat Rate Interest?

APR (Annual Percentage Rate) is the true cost of borrowing and includes all fees. Always compare loans using APR, not flat rate. A loan advertised at '5% flat rate' actually has an APR of approximately 9–10% because you're paying the same interest amount even as your balance reduces. APR is the legally required comparison figure in the UK and EU.

How Monthly Payments Are Calculated?

Monthly payment = P × (r(1+r)^n) / ((1+r)^n − 1), where P is the principal, r is monthly interest rate, and n is months. In the early months, most of your payment goes to interest. In the final months, most goes to principal. This is called amortisation — which is why extra payments early in the loan save significantly more interest than the same payment made later.

When to Make Extra Payments?

Extra payments reduce the outstanding balance immediately, meaning less interest accrues on the next cycle. On a 3-year £10,000 loan at 6.5%, paying an extra £100/month from month 1 saves approximately £280 in interest and pays off the loan 10 months early. Check your loan agreement for early repayment charges — most UK personal loans allow overpayments without penalty.

What's the key thing to understand about Best and Worst Loan Uses?

Lowest risk: consolidating higher-rate debt into a single lower-rate loan. Generally acceptable: essential purchases (car for work, necessary home repair). Poor use: discretionary spending, holidays, or items that depreciate quickly. The true cost test: does the total interest paid justify the purchase? A £500 holiday loan at 20% APR over 2 years costs £110 in interest — ask if that's worth it.

What should I know about How Amortisation Shifts Over the Loan Term?

Each fixed monthly payment on a standard repayment loan is split between interest and capital, but that split isn't constant — in the early months, a larger share of the payment goes toward interest (calculated on the full outstanding balance), and only a small portion reduces the principal. As the balance falls, interest charged each month shrinks, so a growing share of each identical payment goes toward paying down capital. On a long-term loan like a mortgage, this effect is dramatic: in the first few years, the majority of each payment can be interest, with the balance barely moving, while in the final years, almost the entire payment reduces the principal. This is why making extra payments early in a loan's term reduces total interest paid far more than the same extra payment made near the end — early repayment avoids interest that would otherwise be charged on that capital for the rest of the loan's full term, while a late extra payment only avoids a few months of remaining interest.

What's the key thing to understand about Secured vs Unsecured Loans?

An unsecured loan (most personal loans and credit cards) isn't tied to a specific asset — if you default, the lender can pursue the debt through the courts and damage your credit record, but they can't automatically repossess a named asset. A secured loan (mortgages, logbook loans, and some larger personal loans marketed as 'homeowner loans') is backed by a specific asset, usually your home or vehicle, which the lender can repossess and sell if repayments stop. Because secured loans carry less risk for the lender, they typically offer lower interest rates and allow larger amounts to be borrowed over longer terms than an unsecured loan would — but the trade-off is real: missing payments on a secured loan risks losing your home or car, not just your credit score. Before taking a secured loan to consolidate unsecured debt (a common use case, since it can lower the interest rate), it's worth weighing that lower cost against converting previously unsecured debt into debt that puts a specific asset at risk if circumstances change.

Why Two Loans With the Same Rate Can Have Very Different Total Costs

The total interest paid on a loan depends on three interacting factors: the interest rate, the loan term, and the repayment frequency and structure — and changing any one of them, even while holding the rate constant, can significantly change the total cost. A longer term lowers the monthly payment but increases total interest paid, since interest accrues for more periods even though the rate itself hasn't changed. This is why comparing loan offers purely on interest rate, without also comparing term length and total repayable amount, can lead to choosing a loan that looks cheaper per month but actually costs considerably more over its full life.

Why Extra Payments Toward Principal Have an Outsized Effect Early in a Loan

Making extra payments directly toward principal, beyond the required monthly payment, reduces the balance that future interest is calculated on for every remaining period of the loan — which is why extra payments made early in a loan's term generally save more total interest than the identical extra payment made later, since the early payment removes that amount from the interest calculation for a longer remaining stretch. Before making extra payments a habit, it's worth checking whether the specific loan carries any early repayment charge or prepayment penalty, since some loans — particularly certain fixed-rate products — limit penalty-free overpayments to a set amount per year, with charges applying above that limit during specific periods of the loan.

Reference: Total Interest by Term and Rate (£10,000 Loan)

Extending the term always increases total interest paid, even though it lowers the monthly payment — the trade-off is cash-flow relief today against a larger total cost over the life of the loan, and the gap widens sharply at higher APRs, which is exactly where borrowers under the most monthly-budget pressure are often tempted to stretch the term furthest.

Worked Example: How a Payment Splits Between Interest and Principal

A £10,000 loan at 12% APR over 3 years (36 months) has a monthly payment of approximately £332. Month 1: interest = £10,000 x 12%/12 = £100; principal repaid = £332 - £100 = £232; balance falls to £9,768 Month 18 (halfway): balance has fallen to roughly £5,300; interest that month = £5,300 x 1% = £53; principal repaid = £332 - £53 = £279 Month 36 (final): balance is nearly zero; almost the entire £332 payment is principal, with only a few pence of interest Over the full term, this loan pays roughly £1,970 in total interest on top of the £10,000 borrowed. Notice how the principal portion of each payment grows steadily through the term even though the payment itself stays flat — this is the normal amortisation pattern for any fixed-rate instalment loan, and it is why an extra lump-sum payment made early in the term (when more of each payment is still interest) saves considerably more total interest than the same extra payment made near the end.

How Your Credit Score Changes the Rate You're Actually Offered

Advertised loan rates are typically only available to borrowers with the strongest credit profiles, and lenders are required to offer the advertised rate to at least a majority of successful applicants, which still leaves plenty of room for someone with a thinner or more troubled credit history to be offered a noticeably higher rate, or declined outright. A borrower with an excellent credit score might be offered a representative rate, while someone with a few missed payments on record could see a rate several percentage points higher for an identical loan amount and term, which can easily shift total interest by hundreds or thousands of pounds over the loan's life. Checking your credit report before applying, and correcting any errors, is one of the few genuinely free ways to improve the rate actually offered.

Fixed vs Variable Rate Loans: Where the Risk Sits

A fixed-rate loan locks in the interest rate for the full term, giving certainty over the exact monthly payment and total cost from day one, which suits anyone who values predictable budgeting or expects rates to rise. A variable-rate loan can move up or down with the lender's reference rate or a central bank rate, meaning payments could fall if rates drop, but could also rise unexpectedly, which is a real risk for a borrower with little financial slack. Most personal loans in the UK are fixed-rate, while mortgages more commonly offer a choice; the core trade-off is the same either way — fixed trades potential savings for certainty, variable trades certainty for potential savings, and the right choice depends on how much payment-shock risk a borrower can comfortably absorb.