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Debt Payoff Calculator: Snowball vs Avalanche

Your debts
$
Debt-free in
Total interest
Total paid
Avalanche saves $374 in interest compared with Snowball.

Payoff order

1Credit card2Personal loan3Car loan

Seeing How Long a Balance Will Take

A credit card statement shows a minimum payment and a balance, and the relationship between them is not obvious. Paying the minimum on a card at a typical rate can take decades and cost more in interest than the original balance, and nothing on the statement makes that visible at a glance.

This calculator projects how long a debt takes to clear at a given payment, how much interest it accrues, and what happens when you pay more.

How to Use the Payoff Calculator

Three inputs give the whole picture: what you owe, the rate, and what you pay each month.

  1. Enter the outstanding balance.
  2. Enter the rate the debt carries. Card statements show it as an APR, and the calculator converts that to a monthly rate.
  3. Enter your monthly payment. Start with what you currently pay to see the baseline.
  4. Read the payoff time and the total interest. The interest figure is usually the one that changes people’s minds.
  5. Increase the payment and compare. The saving from an extra amount each month is larger than most people expect, because it compounds against the remaining balance.
  6. For several debts, run each separately and compare the interest rates, that comparison is what decides the order to tackle them in.

Why Minimum Payments Take So Long

A minimum payment is typically calculated as a small percentage of the balance, often around 2%, with a floor. Because it falls as the balance falls, the payment shrinks alongside the debt and the end never quite arrives. Most of an early minimum payment goes to interest rather than principal, which is why the balance barely moves in the first year.

Fixing the payment amount instead changes the shape entirely. Paying a constant sum means that as interest falls with the balance, more of each payment attacks the principal, and the debt clears in a fraction of the time. On a typical card balance the difference between paying the minimum and paying a fixed version of that same initial amount can be a decade.

A 5,000 Balance at 20% APR

How the monthly payment changes the outcome on the same debt.

Monthly paymentTime to clearTotal interestTotal paid
100Never, interest exceeds it
125About 8 years~6,900~11,900
1504 years 4 months~2,800~7,800
2002 years 8 months~1,500~6,500
2502 years 1 month~1,150~6,150
4001 year 2 months~600~5,600

Note the first row. At 20% APR a 5,000 balance accrues about 83 a month in interest, so a payment below that never reduces the principal at all. Any payment near the interest charge leaves the debt essentially permanent.

Avalanche, Snowball and Which to Choose

With several debts, the avalanche method pays the highest interest rate first, which is mathematically optimal and always costs the least in total interest. The snowball method pays the smallest balance first, which costs slightly more but clears individual debts sooner and gives visible progress.

The difference in total cost is usually modest, and the better method is the one you keep doing. Where the gap in rates is large, a 25% card against a 4% loan, avalanche is worth the discipline. Where rates are similar, snowball’s early wins are a reasonable trade for a small amount of extra interest.

Frequently Asked Questions

Why does paying the minimum take so long?
Because the minimum is a percentage of the balance, so it falls as the balance falls. Most of an early payment goes to interest, and the shrinking payment means the end keeps receding.
What happens if my payment is less than the monthly interest?
The balance grows rather than shrinks. At 20% APR a 5,000 balance accrues about 83 a month, so anything below that never touches the principal.
Does paying a little extra really help?
Substantially. The extra goes entirely against principal, which reduces the interest charged next month, so the effect compounds rather than being linear.
Should I pay off the highest rate or the smallest balance first?
Highest rate costs least in total interest. Smallest balance clears individual debts sooner and is easier to sustain. The difference is usually modest, so pick the one you will keep to.
What is APR and how does it differ from the monthly rate?
APR is the annual rate. The monthly rate is roughly the APR divided by twelve, which is what gets applied to the balance each statement period.
Does this account for fees?
No. Annual fees, late charges and balance transfer fees are not included, so a real card may cost more than the projection shows.
Is my financial data private?
Yes. Everything is calculated in your browser and nothing you enter is transmitted or stored.

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