Debt payoff calculator
If you only pay the minimum, interest absorbs much of each payment and the balance can drag on for years. This tool projects months to clear, total interest, and how much time and interest you save by adding a fixed extra payment each month.
With $50,000 at 24% APR, minimum $1,500/month and $500 extra:
- No extra: 56 months (4 years 8 months), interest ≈ $33,220.87, total ≈ $83,220.87
- With +$500: 36 months (3 years), interest ≈ $20,005.63, total ≈ $70,005.63
- Saved: 20 months and ≈ $13,215.24 in interest alone If the extra rises to $1,000, payoff drops to 26 months and interest saved is about $18,727.23.
What this tool calculates
- Payoff time with the monthly minimum only
- Payoff time with minimum + extra payment
- Total interest in both scenarios
- Interest saved and months saved when you pay more
- A short monthly breakdown in the engine (first months)
The model is one consolidated debt (one balance, one rate, one minimum). Use it for a single card, a loan, or balances with a similar rate. For ordering several different debts, use snowball or avalanche (below) and run one scenario per debt: or consolidate first.
How the model works
Each month interest accrues on the remaining balance, then the payment (minimum or minimum + extra) is applied. Anything above interest reduces principal.
monthly_rate = annual_rate / 12 / 100
month_interest = balance × monthly_rate payment = minimum (+ extra, if any) if payment ≤ interest → the debt is not sustainably shrinking else → balance = balance + interest − payment
The loop repeats until the balance is ~0 (safety cap: 600 months). It is an educational fixed-payment model; a real bank minimum may be a % of balance, a floor, or include insurance.
Step-by-step example (defaults)
Inputs: debt $50,000 · 24% APR · minimum $1,500 · extra $500
- Monthly rate = 24% / 12 = 2%
- First month without extra: interest = 50,000 × 0.02 = $1,000; principal = 1,500 − 1,000 = $500
- Minimum only clears in 56 months (interest ≈ $33,220.87)
- Minimum + $500 (effective $2,000) clears in 36 months (interest ≈ $20,005.63)
- Difference: 20 fewer months and ≈ $13,215 less interest
Reference table (same engine assumptions)
Rounded with the calculator logic. Use your own inputs above for an exact result.
| Debt | APR | Min / mo | Extra / mo | Months (no extra) | Months (with extra) | Interest (no extra) | Interest (with extra) | Interest saved | Months saved |
|---|---|---|---|---|---|---|---|---|---|
| $50,000 | 24% | $1,500 | $500 | 56 | 36 | $33,220.87 | $20,005.63 | $13,215.24 | 20 |
| $50,000 | 24% | $1,500 | $1,000 | 56 | 26 | $33,220.87 | $14,493.64 | $18,727.23 | 30 |
| $20,000 | 42% | $1,000 | $0 | 35 | 35 | $14,997.80 | $14,997.80 | $0 | 0 |
| $20,000 | 42% | $1,000 | $500 | 35 | 19 | $14,997.80 | $7,414.26 | $7,583.54 | 16 |
| $15,000 | 36% | $800 | $400 | 28 | 16 | $7,374.18 | $4,082.34 | $3,291.84 | 12 |
| $30,000 | 18% | $1,200 | $300 | 32 | 24 | $7,883.78 | $5,934.80 | $1,948.98 | 8 |
| $10,000 | 30% | $500 | $250 | 29 | 17 | $4,035.93 | $2,317.63 | $1,718.29 | 12 |
| $8,000 | 48% | $500 | $200 | 27 | 16 | $5,024.84 | $2,906.68 | $2,118.16 | 11 |
Avalanche vs snowball (multiple debts)
When you have more than one balance, order matters.
Avalanche method
Pay the minimum on all debts → put every extra dollar on the highest APR → when it clears, roll that payment to the next highest rate
Advantage: usually minimizes total interest. Best when rate gaps are large (e.g. 42% card vs 18% loan).
Snowball method
Pay the minimum on all debts → put every extra dollar on the smallest balance → when it clears, roll that payment to the next smallest
Advantage: motivation from quick wins. It can cost a bit more interest but is often easier to stick with.
Using this calculator with several balances
- List each debt: balance, APR, and minimum.
- Choose avalanche or snowball.
- Simulate the “attack” debt with minimum + all available extra.
- When it clears, add that payment to the next debt’s extra and resimulate.
- For a single card with a fixed payment, also try the credit card payment calculator.
Why minimums feel “safe” but cost so much
Staying current avoids late fees, but the minimum is designed to keep the account open: not to minimize interest. In the $20,000 @ 42% row with $1,000/month, interest alone is nearly $15,000 (~75% of principal). Adding $500 extra cuts 16 months and saves ~$7,584 in interest.
The balance will not shrink sustainably. Raise the payment, cut the rate (negotiate/refinance), or stop new charges. Compare options with a personal loan only when total cost truly falls.
How to finish sooner and pay less interest
- Any stable extra (even a small amount) cuts months and interest: compare rows in the table.
- Avoid new charges while paying down: each purchase restarts interest on a higher balance.
- Check capacity with debt-to-income ratio before consolidating or taking new credit.
- If moving card balances to a loan, simulate the installment with personal loan and extra principal with early loan payoff.
- Free cash flow with a monthly budget and send the surplus to the extra field.
- For principal-vs-interest by period, use the amortization table.
Common mistakes
- Thinking the minimum is “fine” because you are not late: total cost can exceed principal.
- Entering a payment that does not cover monthly interest.
- Comparing only a comfortable payment and ignoring total paid.
- Consolidating and reusing the card at the same time.
- Forgetting insurance, annual fees, and commissions in the effective payment.
- Mixing very different APRs into one scenario without prioritizing the most expensive debt.
What is included and what is not
Included (reference model):
- Monthly interest on remaining balance (APR / 12)
- Minimum vs minimum + extra comparison
- Interest and time saved
- Payoff horizon safety cap
May not match your statement:
- Variable or regulated minimums (% of balance)
- Grace periods, 0% promos, or installment plans
- Late fees, penalties, and different compounding
- Taxes/fees on commissions or insurance that change with balance
- Biweekly or irregular payments
- Automatic multi-debt ordering (simulate avalanche/snowball step by step)
This tool is educational and is not credit advice or an offer from any lender. Real rates, minimums, and fees depend on your contract, credit history, and issuer. Review your statement and current terms before consolidating, negotiating, or restructuring.
FAQ
Any stable amount helps. In the $50,000 @ 24% example, $500 extra saves ~20 months and ~$13,215 of interest; $1,000 extra cuts payoff to 26 months. Start with what fits your budget and increase when you can.
Avalanche usually saves more money (highest rate first). Snowball prioritizes small balances and motivation. If rates are similar, pick the plan you will actually follow.
Build a basic emergency fund (1–3 months of essential expenses). Then prioritize expensive debt (high-teens+ cards): interest paid almost always beats liquid savings returns.
Only if the loan’s rate + fees lower total cost and you commit not to rebuild card debt. Compare with a personal loan and check your DTI.
Often yes: especially with a strong payment history or a competitive balance-transfer option. Any rate cut multiplies the effect of your extra payment.
Simulate each separately, or sum only balances with a similar APR. To order attacks across different debts, use avalanche/snowball and reassign the extra when one account closes. For a single card with a fixed payment, also use the credit card payment calculator.