Debt Consolidation Calculator
Introduction: should you consolidate your debt?
Debt consolidation means replacing multiple balances (credit cards, personal loans, medical financing, etc.) with one new loan. The main promise is simplicity (one payment) and—if your new APR is meaningfully lower—potential savings in monthly payment, total interest, or both. But consolidation can also increase total cost when the new term is longer, when fees are added, or when the new APR isn’t actually lower. A pitch that leads with "one low monthly payment" is really selling cash flow, not savings, and the two are not the same thing.
This calculator keeps those two effects separate so a smaller monthly bill can't disguise a larger lifetime interest cost. It compares:
- Your current plan: up to three existing debts, each with its own balance, APR, and years remaining.
- A proposed consolidation loan: one new APR and one new term (years) applied to the combined balances.
How to use this debt consolidation calculator
Pull up a recent statement for each balance you want to fold together—you need the current payoff amount, the APR, and a realistic estimate of how many years are left at your current pace. Then:
- Enter debt 1. This row is required. Type the balance in dollars, the APR as a percentage (e.g.
18.99, not0.19), and the years remaining (decimals are fine—1.5means eighteen months). - Add debts 2 and 3 if you have them. These rows are optional; leave a row completely blank to skip it. Fill in all three fields of any row you use.
- Describe the offer. Enter the consolidation loan's new APR and its term in years. The tool adds up only the balances you filled in and applies this single rate and term to that combined principal.
- Press Calculate comparison. You'll get your current combined monthly payment and remaining interest side by side with the consolidation loan's payment and interest, plus the month-to-month change and lifetime interest saved (or lost).
Minimum inputs: at least one existing debt (balance, APR, years remaining) plus the consolidation loan's APR and term. If a debt is truly interest-free, enter 0 for its APR—the calculator handles a zero rate as simple principal ÷ months.
How the calculations work (formulas)
Each debt is treated as a fixed-rate installment loan amortized with equal monthly payments. For each existing debt i:
- Balance: L
- APR (annual percentage rate): APR
- Years remaining: Y
Convert APR to a monthly rate and years to number of payments:
- r = APR / 100 / 12
- n = 12 × Y
The standard monthly payment formula is:
Total paid and total interest for that debt are:
- Total paid = P × n
- Total interest = (P × n) − L
For the consolidation loan, the principal is the sum of the included balances:
- Lnew = L1 + L2 + L3 (only rows you fill in)
Then the same amortization math is applied using the new APR and new term.
What the payment and interest comparison tells you
When you press Calculate, you should focus on three comparisons:
- Monthly payment difference: A lower payment improves cash flow, but it may come from stretching the term.
- Total interest difference: This is the long-run cost comparison (often the most important).
- Tradeoff between APR and term: Even a lower APR can cost more overall if the new term is much longer.
When consolidation tends to help
- You qualify for a meaningfully lower APR than your weighted average rate today.
- You keep a similar (or shorter) payoff timeline.
- Fees are low and you don’t replace paid-off debt with new borrowing.
When it can hurt
- The new term is longer, increasing total interest even if the payment drops.
- Origination fees, closing costs, or balance transfer fees offset savings.
- Promotional rates expire (e.g., 0% balance transfers) and the effective APR becomes higher.
Worked example: rolling three balances into one loan
Assume you have the following debts:
- Debt 1: $5,000 at 18% APR with 3 years remaining
- Debt 2: $8,000 at 12% APR with 4 years remaining
- Debt 3: $3,000 at 9% APR with 2 years remaining
Total current principal is $16,000. Run each balance through the amortization formula and today's three payments come to roughly $181, $211, and $137 a month—about $528 combined—with around $3,909 of interest still left to pay across the three payoff timelines.
Now suppose you're offered a consolidation loan at 10% APR for 5 years. Applying the same formula to $16,000 at 10% over 60 months gives a single payment of about $340 a month and roughly $4,397 in total interest.
Line those up and the trap is obvious: the monthly payment falls by nearly $188, which feels like a win, but lifetime interest actually climbs by about $488. You lowered the bill by stretching the shortest debts (the 2- and 3-year balances) out to a full five years. That is the whole point of separating the two numbers—when the payment drops but total interest rises, you're buying short-term breathing room at a long-run cost. Consolidation looks genuinely better when both figures fall after any origination or transfer fees are folded in.
Quick comparison: consolidate vs. keep separate
| Factor | Keep current debts | Consolidate into one loan |
|---|---|---|
| Number of payments | Multiple due dates and minimums | One payment |
| Monthly cash flow | Often higher if rates are high | May be lower (especially with longer term) |
| Total interest paid | Depends on each APR and remaining term | Lower only if APR/term/fees are favorable |
| Fees | Usually none going forward | May include origination, closing, or transfer fees |
| Flexibility | You can target extra payments to highest APR first | One blended balance; prepayment rules vary |
Assumptions & limitations
- Fixed-rate amortization: Calculations assume each debt (and the new loan) has a fixed APR and a fully amortizing payment schedule.
- Monthly compounding approximation: APR is converted to a monthly rate by dividing by 12. Some lenders compute interest differently (daily interest or different compounding conventions), which can change results slightly.
- No fees included by default: Origination fees, balance transfer fees, closing costs, annual fees, and prepayment penalties are not automatically added. To approximate fees, you can add them to the consolidation principal (increase balances) or adjust the APR upward to an “effective” rate.
- No missed payments: Late fees, penalty APRs, and credit impacts are not modeled.
- Rounding: Payments and interest totals are subject to rounding; small differences vs. lender statements are normal.
- Revolving credit nuance: Credit cards don’t always amortize like installment loans. This tool is most accurate when you are on a payoff plan with a fixed term equivalent.
Common questions about debt consolidation
Should I consolidate if my monthly payment goes down?
Not automatically. A lower payment can come from extending the term, which may increase total interest. Check both monthly payment and total interest (and include any fees).
How do I account for origination or balance transfer fees?
Add the fee amount to the balance you’re consolidating (as if it increases principal), then compare totals again. Alternatively, compare results with a slightly higher APR to approximate the fee’s effect.
Will consolidation improve my credit score?
It can help or hurt depending on utilization, on-time payment history, and whether you close old accounts. This calculator estimates costs, not credit outcomes.
Is a 0% balance transfer the same as a consolidation loan?
It’s a form of consolidation, but promotional rates often expire and fees (like 3%–5%) can apply. Model it by using the promo period as the “term” only if you expect to pay it off before the rate changes.
Mini-Game: Interest Avalanche
Slide your payoff shield, collect refinance boosts, and stop high-APR debt spikes from snowballing your balance pressure.