Loan calculator
Calculate monthly payment and total repayment for an annuity loan. Change amount, term and rate — the result updates instantly.
This is an indicative annuity calculation. APR may be higher due to arrangement fees.
Why instalment intuition is usually wrong
Ask someone what a €5,000 loan over three years at 10% costs and the common answer is €5,000 plus 10% — around €5,500. The real figure is closer to €5,800, and the reason is that interest is charged on the balance that is still outstanding, not on the original sum. Every payment reduces that balance, so the interest portion shrinks month by month while the payment itself stays the same.
That single mechanism explains most of the surprises in private lending. It is why doubling the term far more than doubles the interest, why a low rate on a long loan can cost more than a high rate on a short one, and why two offers that look similar on the surface can differ by hundreds of euros.
The calculator above removes the guesswork. Enter the amount, the term and the annual rate, and it returns the monthly instalment, the total interest and the total repayment. Everything below explains what those three numbers mean and where they stop being reliable.
The annuity formula in plain language
An annuity loan keeps the monthly payment constant for the whole term. Inside that fixed payment the split moves: at the start most of it is interest, at the end most of it is principal. This is the standard structure for consumer credit and for almost every peer-to-peer agreement between private individuals.
The payment is derived from three inputs. The principal is the amount borrowed. The periodic rate is the annual rate divided by twelve. The number of periods is the term in months. The formula multiplies the principal by the periodic rate, then divides by one minus the discounted growth factor over the term — mechanically, it spreads the interest evenly across equal payments.
The practical consequence is worth remembering without the algebra: an instalment reacts strongly to the term and weakly to the rate. Shortening a loan from 48 to 24 months changes the monthly figure far more than shaving two percentage points off the interest. When a payment does not fit the budget, the term is the lever that moves.
What the calculator includes and what it leaves out
The calculation covers principal and interest on an annuity schedule. It does not know about anything the parties agree separately, and in private lending that list is longer than most borrowers expect.
Treat the output as the floor of the cost, never the ceiling. A payment that only just fits before fees will not fit once fees exist.
- Arrangement or handling fees charged by a platform are outside the calculation — on a classifieds board like this one there are none, only the listing fee.
- Late-payment interest and collection costs appear only if a payment is missed, and they are set by law rather than by the calculator.
- Any agreed instalment holiday extends the term and increases total interest, which the default calculation does not model.
- Early repayment lowers the total cost; the calculator assumes the schedule runs to the end.
- Currency, transfer and account fees are ignored — normally trivial within Finland, relevant across borders.
Reading the result: three numbers that matter
The output is deliberately short. Each figure answers a different question, and confusing them is the most common source of bad decisions on both sides of a private loan.
Monthly instalment
The affordability test. It has to survive an ordinary bad month — an unexpected repair, a delayed invoice, a sick child — not just an average one.
Total interest
The price of the arrangement. This is the number to compare between two offers, because it is the only one that captures rate and term together.
Total repayment
The reality check. Seeing €5,800 against a €5,000 need often changes the amount requested, which is exactly what it is there for.
How the term changes the total
The clearest way to see the effect of the term is to hold the amount and the rate constant and move only the months. The table below does that for €5,000 at 10% per year.
| Term | Monthly instalment | Total interest | Total repaid | Interest as share |
|---|---|---|---|---|
| 12 months | ≈ €440 | ≈ €275 | ≈ €5,275 | 5.5% |
| 24 months | ≈ €231 | ≈ €540 | ≈ €5,540 | 10.8% |
| 36 months | ≈ €161 | ≈ €810 | ≈ €5,810 | 16.2% |
| 48 months | ≈ €127 | ≈ €1,090 | ≈ €6,090 | 21.8% |
| 60 months | ≈ €106 | ≈ €1,375 | ≈ €6,375 | 27.5% |
Rounded figures for comparison. The instalment falls by three quarters between 12 and 60 months, while the interest paid multiplies by five.
For a borrower the reading is simple: take the shortest term the budget genuinely tolerates, not the longest one available. For an investor the same table is a risk chart — a sixty-month loan gives five years for the counterparty situation to deteriorate, which is why longer private loans usually carry a higher rate or a form of security.
What interest rate is realistic between private individuals
There is no published price list for private lending, because every agreement is negotiated. In practice the rates that appear on Finnish boards cluster in a fairly narrow band, and the position within it is set by security and by how well documented the repayment source is.
Loans between relatives are often agreed at or near a nominal rate. Loans between strangers without collateral sit far higher, because the lender has no recovery route other than the courts. Between those poles, a guarantor, a pledged vehicle or a short term all pull the rate down.
A useful way to negotiate is to argue in euros rather than in percentages. The difference between 9% and 12% on a €4,000 loan over two years is roughly €130 in total interest — an amount both parties can weigh against something concrete, such as a guarantor, a shorter term or a deposit against the vehicle being financed. Framed as three percentage points the same gap sounds abstract and tends to stall the conversation; framed as €130 against a named piece of security it usually settles it in one message.
There is one hard boundary. Consumer protection legislation caps interest only when the lender acts as a trader; between two private individuals it does not apply. What does apply is the criminal provision on usury, which makes an agreement voidable and punishable when the terms are grossly disproportionate and exploit the other party. A rate far above the market band is therefore not just expensive — it is legally fragile, as explained in loan agreement terms.
What a missed payment costs
Late-payment interest between private individuals is not a matter of negotiation unless a higher rate has been agreed within legal limits. The interest act sets it as the Bank of Finland reference rate plus seven percentage points, running from the due date until payment.
Collection costs are added on top and escalate: a reminder is cheap, an external collection agency is not, and a court order adds filing costs and a payment default entry that follows the debtor for years. For the lender none of this is profit — it is money spent chasing money.
This is why the schedule matters more than the rate when a loan is being sized. A payment that fits comfortably almost never reaches this stage; a payment that only just fits reaches it regularly. The consequences of a default entry are covered in the no-credit-check guide.
Costs that never appear in a calculator
Two categories of cost sit outside every instalment calculation, and both are worth pricing before signing.
Documentation
A written agreement is free to produce, but witnessing, notarisation for larger sums or a lawyer reading the draft are not. On a €20,000 loan they are cheap insurance.
Enforcement
If the debt is ever disputed, the cost of proving it is the real expense. A signed promissory note with identified parties makes that cost small; a chat log makes it large.
The buffer test before you commit
Affordability is not the instalment against income. It is the instalment against what remains after everything that must be paid anyway — rent, energy, food, transport, existing credit, insurance.
A workable rule for private loans: the new instalment should consume no more than half of that remainder, leaving the other half as a buffer. Below that threshold a bad month is inconvenient; above it a bad month becomes a missed payment.
For the borrower
If the buffer test fails, reduce the amount before extending the term. A smaller loan repaid quickly beats a larger loan carried for years.
For the investor
Ask for the same arithmetic. A borrower who can show the calculation has already thought about repayment; one who cannot has thought only about receiving.
Comparing a private offer with a bank offer
A bank quotes an annual percentage rate that bundles interest and mandatory fees into a single comparable figure. A private lender quotes a nominal rate and usually has no fees at all. Comparing the two headline numbers directly therefore flatters the bank offer.
The honest comparison uses total repayment. Run both offers through the calculator with their own rates and terms, add any bank fees to the bank total, and compare the two sums. On small, short loans the private route often wins on price; on large, long loans the bank usually wins, because its cost of funds is lower.
Price is not the only axis. A bank absorbs the administrative work and the collection risk; a private agreement leaves both with the parties. The platform comparisons under loans and P2P platforms set out where each model earns its cost.
From the calculation to the agreement
The numbers only become binding when they are written down. The agreement should repeat the exact figures the calculator produced — principal, annual rate, instalment, number of payments, first and final due dates — so that no later dispute turns on what was meant.
Anything the calculation assumed silently should also be stated: whether early repayment is allowed without penalty, what happens to the schedule if a payment is postponed, and which account receives the money. The full clause list is on loan agreement terms, and the general mechanics of a private loan are covered in the P2P loan guide.
Tax on interest received
Interest earned on a private loan is capital income for the lender in Finland and is taxed accordingly — the standard capital income rates apply, with the higher band starting above the annual threshold. No tax is withheld automatically on a private loan, so the income has to be declared.
The borrower has the mirror position: interest on a private consumer loan is generally not deductible, unlike interest on a mortgage in the cases where deduction still applies. The lender therefore keeps less than the headline rate suggests, which is worth factoring in before agreeing a figure — the numbers are discussed further in investing in P2P lending.
Three worked situations
Abstract percentages persuade nobody. The three cases below are the ones that come up most often on a private lending board, run through the same annuity calculation.
| Situation | Amount | Term | Rate | Monthly | Total repaid |
|---|---|---|---|---|---|
| Car repair before the inspection deadline | €1,500 | 9 months | 8% | ≈ €172 | ≈ €1,551 |
| Consolidating three small credits into one | €6,000 | 30 months | 11% | ≈ €229 | ≈ €6,875 |
| Bridging an unpaid invoice in a small business | €10,000 | 6 months | 12% | ≈ €1,725 | ≈ €10,352 |
Rounded. The business case is covered separately in the P2P loan guide, where the investor view of company risk is set out.
The pattern across all three is the same: short terms keep the interest almost irrelevant, and it is the length of the loan rather than its headline rate that decides the final bill. A borrower who needs a long term usually needs a smaller loan instead — the reasoning is expanded in the risks guide.
Common mistakes with loan calculators
- Entering a monthly rate as if it were annual — a twelvefold error that makes a reasonable loan look catastrophic, or the reverse.
- Comparing a nominal private rate against a bank APR without adding the bank fees to the comparison.
- Treating the instalment as the affordability test instead of the instalment against the remaining budget.
- Assuming the total is fixed when the agreement allows postponed payments, which quietly extend the term.
- Calculating for the amount wanted rather than the amount needed — the fastest way to fail the buffer test on paper.
- Forgetting that the figures mean nothing until they are in a signed agreement between identified parties.
Running the calculation step by step
The calculator answers whatever it is given, so the order of the inputs decides whether the answer is useful. Six steps, in this order, take about three minutes.
- Start from your monthly surplus, not from the sum you want. Deduct rent or mortgage, existing loans and living costs from net income; what remains is the ceiling for the instalment.
- Enter the principal as it appears in the agreement, adding any drawdown or arrangement fee to it. The figure that lands in your account is not the figure you owe.
- Convert the rate to an annual one before typing it in. A rate quoted per month or per week has to be annualised first, or the result is meaningless.
- Set the term you actually intend to repay over, then read the total cost rather than the instalment alone.
- Compare two offers only on the same term. On different terms the smaller instalment can hide a larger total.
- Repeat with the amount reduced by a quarter. If the second run fits your surplus and the first does not, you have found the realistic sum — take that one to the listings.
What the calculation requires from your inputs
A calculator does not know what was left out of it. Four inputs have to be right, otherwise the result is precise and wrong at the same time.
Principal including fees
Any drawdown or arrangement charge belongs in the principal. Leave it out and the interest cost is understated, sometimes by more than the fee itself.
An annual rate
Four per cent a month is roughly sixty per cent a year, not four. If the quote is not annual, annualise it before entering it.
One term for both offers
Two offers are only comparable over the same number of months. This is the single most common source of a wrong conclusion.
A surplus figure you have actually calculated
An estimate of what you can afford is not an input. Work it out from bank statements for two or three months and use that — the requirement is explained on P2P loan in Finland.
Advantages and drawbacks of planning with a calculator
Advantages
It turns an argument into arithmetic: the instalment either fits the surplus or it does not. It exposes the cost of a longer term, which is where most of the money is lost. And it runs entirely in the browser, so nothing about your finances is sent anywhere.
Drawbacks and limits
It only models an annuity loan with a fixed rate. It cannot price a variable rate, an interest-only period, a balloon payment or a default. Nor does it know the fees the other party has not disclosed — those have to be added by hand.
Who needs more than this
If the loan is secured on property, or the term runs over several years with a variable rate, a single annuity figure is not enough for a decision. Ask the lender for a full amortisation schedule instead.
What the result is not
It is not an offer, not a credit decision and not advice. Vertaislaina24 neither grants nor brokers loans; the figure is a planning tool for reading someone else’s terms.
If the numbers do not work and the application is refused
Most refusals are visible in the calculation before any application is sent: the instalment does not fit the surplus. When that is the case, the answer is a different figure in the same calculation, not a second application somewhere else.
- Cut the principal by twenty to thirty per cent and run it again. This changes the outcome more than stretching the term does.
- Extend the term only as a second move, and look at the total cost while you do — the difference often runs to hundreds of euros.
- Check your own credit record with the register keeper. An incorrect entry can be corrected free of charge, and correcting it changes the decision.
- Ask for the reason for a rejection in writing. Several applications in the same week stay visible and make the next answer worse.
- If no version of the calculation fits your surplus, the issue is not access to credit. Municipal financial and debt counselling is free and statutory — the situation is worked through on the investor side as well, where the same shortfall appears as a credit loss.
Frequently asked questions
Does the calculator work for peer-to-peer loans?+
Yes. Almost all private loans use the same annuity structure as consumer credit, so the calculation is identical — only the rate and the absence of fees differ.
Why is the total higher than amount plus rate?+
Because interest accrues on the outstanding balance every month of the term, not once on the original sum. The longer the term, the larger the gap.
Can I calculate a bullet loan where only interest is paid monthly?+
Not directly. For a bullet structure the monthly interest is simply the principal times the annual rate divided by twelve, with the principal repaid in full at the end.
Is the result binding on either party?+
No. It is an estimate for planning. Only the figures written into the signed agreement have legal effect.
What rate should I enter if none has been agreed yet?+
Try the range you expect to negotiate and look at the difference in total repayment. That figure tells you how much the negotiation is actually worth.
Does paying the loan back early save money?+
Yes, and usually more than expected. Interest accrues on the outstanding balance, so every early payment removes the interest that balance would have generated for the rest of the term. Agree the right to repay early in writing, because without a clause the lender may refuse.