Free debt calculator
The Snowball Plus™ Debt Planner is a free debt payoff calculator. Enter each debt's balance, interest rate, minimum payment and any 0% deal, add what you can pay on top, and it estimates your debt-free date, the interest you'll pay, and which debt to put your extra money into first.
It runs in your browser, needs no account, and never connects to your bank. Everything it does with your numbers is written out on this page, so you can check the method before you trust the result.
No login · no email · no bank connection · GBP, USD, EUR, CAD, AUD
Inputs
What do you enter into the debt calculator?
For each debt, the calculator needs four things: what you owe, what it charges, what the lender makes you pay each month, and whether any part of it is on a deal that ends. Then one figure for the whole plan: what you can pay on top of your minimums. Everything else is optional.
| Field | What to enter |
|---|---|
| Debt name | Anything that helps you recognise it — the card, the loan, the store account. |
| Total account balance | The full amount currently owed on that account, from your latest statement or the app. |
| Standard APR | The rate the account charges outside any promotional period. It's on your statement, usually in a summary box. |
| Minimum payment | Defaults to 2.5% of the balance with a £5 floor, which is typical for a UK credit card. Change it to your own percentage, or switch to a fixed amount for a loan or a store account with a set repayment. |
| Promotional rate and deal end month Optional | If the debt is on a 0% or introductory rate, enter the rate and the month the deal ends. The planner tracks the expiry and treats the balance as the standard-rate debt it is about to become. |
| Split balances Optional | For a card carrying more than one kind of balance at once — a 0% balance transfer alongside ongoing purchases, say. Each part gets its own type (purchases, balance transfer, cash advance, store finance, BNPL or instalment, other), its own rate, its own deal end month, and a flag for whether interest can be charged retroactively. |
| Extra monthly payment | What you can reliably put towards debt above every minimum, every month. Without this the planner only models minimum payments, and many debt sets never clear on minimums alone. |
| One-off payment Optional | A lump sum — a bonus, a tax refund, a sale — applied now or in a chosen number of months. It goes to whichever debt is the current target. |
| Starting month | The month the plan begins. This decides which rates are live and when each promotional deal ends. |
| Freed payments | When a debt clears, its payment can roll into the next target or be kept back as breathing room. Rolling it forward clears the rest sooner; keeping it back shows you what your month would feel like with that payment gone. |
On minimum payments and what changing them does to the cost of a card, see MoneyHelper on paying off credit card debt.
Outputs
What does the debt calculator show you?
Six headline figures, one recommended first move, and a comparison of four payoff routes. All of it updates as you type.
| Result | What it means |
|---|---|
| Debt-free by | The estimated month your last balance reaches zero on the current route, with the payments you've entered. |
| Time remaining | The same date expressed as months from your starting month. |
| Interest cost | The estimated total interest you'd pay between now and the debt-free date, on this route. Change the route or the extra payment and watch it move. |
| Starting minimums | The sum of every minimum payment in month one — the amount the plan assumes you can already cover. |
| First payment freed | When the first debt clears and how much monthly payment that releases. |
| Active route and first focus | Which method is driving the order, which debt your extra payment goes to first, and the reason. On the Snowball Plus™ route the reason is one of the four layers below. |
| Strategy comparison | The same debts run through Snowball (smallest balance first), Avalanche (highest APR first), Payment Relief (frees monthly cash soonest) and Snowball Plus™, so you can see what each costs in time and interest before you choose. |
| Plan health and what needs attention | A check that your payments cover the minimums the route needs, and a flag for anything approaching — a deal ending, a deferred-interest deadline — that the figures show. |
Lowest total cost means the least estimated interest. It is not always the fastest payoff, and it is not always the route the planner suggests, because interest is only one of the things going wrong in a real debt situation.
Method
How does it decide which debt to pay first?
On the default route the calculator applies Snowball Plus™, a four-layer method for ordering debt payments. It asks four questions about your debts, always in the same order, and your extra payment goes to the first debt that answers yes. The full method, with the reasoning behind each layer, is published on the method page. In brief:
ProtectNearest harm first.
Debts with the closest, hardest-to-undo consequence — an account tipping into default, a deferred-interest deadline, a 0% rate about to end — are handled before anything is accelerated. The aim is to keep a payoff plan from creating a bigger problem than the debt it is clearing.
Reduce CostCostliest to hold first.
With the urgent handled, extra payments weight toward the balance that costs most to carry — judged on the rate and terms it is about to run at, not only the rate on today's statement.
Reduce PressureEase the squeeze.
Debts that press hardest on the monthly budget get eased where it counts, so the plan stays livable month to month — not just efficient on paper.
MomentumKeep it moving.
Each freed payment rolls forward to the next debt, so visible progress compounds and the plan carries itself once it's underway.
Read left to right: the order protects you first, then works on cost, pressure and momentum together — not one rule applied blindly.
How the numbers are worked out
The arithmetic underneath is a month-by-month projection, and it follows the same rules whichever route you pick. Only the choice of target changes.
- Minimums are paid on every debt, every month.
The planner assumes you keep every required payment up. It never lets an account slide to fund another one, on any route. If your extra payment doesn't cover what the route needs, the plan-health check says so rather than pretending.
- Interest is added at the rate that is live that month.
A debt on a genuine 0% or promotional rate accrues at that rate until the deal end month you entered. From then on the standard rate applies to whatever is still outstanding, going forward. Interest is never back-dated on a plain 0% deal.
- Deferred interest is modelled separately.
If you flag a balance as carrying retroactive interest — common on store finance and some buy-now-pay-later arrangements — the planner treats the deadline as the thing to protect. Under UK rules in force since November 2019, a lender can only back-date interest on the amount still outstanding when the offer ends, not on what you have already repaid, and that is how the planner treats it.
- Your extra payment goes to one target at a time.
Snowball picks the smallest balance; Avalanche the highest APR; Payment Relief the debt whose clearing frees the most monthly cash; Snowball Plus™ the first debt to answer yes to the four questions above. The target is re-chosen each month as balances and dates move, so a 0% card two months from expiry can become the target before its rate changes.
- Split cards are paid the way your lender pays them.
Where one card carries several balance types, the planner applies the payment-allocation rule for the country you choose. The UK option sends payments to the highest-rate balance first, which is what UK card issuers have done since 2011. The US option follows US card rules, where only the part of a payment above the minimum has to go to the highest-rate balance, so the same card can clear in a different order.
- Freed payments roll forward, unless you keep them.
When a debt reaches zero, its minimum plus whatever extra was going to it moves to the next target — or, if you chose breathing room, it's shown as money released rather than reinvested. The projection stops when the last balance reaches zero, and that month is your estimated debt-free date.
Every figure is an estimate. Lenders differ in how they calculate daily interest, when they post it, how they allocate payments, and what fees they add, and the planner doesn't know your account's exact terms. Use the output to choose an order and a monthly amount, then check it against your real statements as you go.
On the difference between a 0% promotional rate and a deferred-interest offer, see MoneyHelper on store and catalogue credit and the FCA’s final rules on Buy Now Pay Later offers (PS19/17). On the snowball and avalanche orderings, see National Debtline on the debt snowball method.
What it leaves out
Where a calculator stops being useful.
This tool orders credit debts you can afford to make payments on. It assumes there is some room to move — that you can cover your minimums and have at least a little to direct. If that isn't your situation right now, no payoff order will fix it.
Priority debts sit outside it entirely: rent or mortgage, council tax, gas and electricity, court fines, TV licence, child maintenance and tax owed to HMRC. Falling behind on those carries consequences interest never does — eviction, disconnection, bailiffs, and in some cases prison. They come first, whatever the calculator says, and the calculator does not rank them.
If you're missing payments you can't catch up on, being chased by creditors, or can't cover your minimums, free and confidential debt advice will do far more for you than any tool. These charities are independent, non-judgemental, and won't try to sell you anything:
StepChange · National Debtline · Citizens Advice on which debts to deal with first
There is no shame in that route. For many people it's the calmest, fastest way back to stable ground — and the calculator will still be here once there's room to move again.
Keeping it current
What the free calculator doesn't do
The free planner gives you an estimate from the figures you type in today. It isn't saved to an account, and it doesn't re-run the order when a balance changes, a deal ends, or an unexpected bill lands. The Snowball Plus™ Debt Hub does: your plan is saved to your email, re-settles each time you update it, and shows the reason beside every debt. One payment, no subscription, no bank connection.
See the Debt Hub →Common questions