How to Calculate Which Debt to Pay First on $68,400: The 5-Variable Formula That Found $8,300 in Savings
The 50/30/20 Rule Gets You Started. Then What?
NerdWallet's budget calculator does one thing really well: it shows you where your money is going. Once you've carved out 20% for debt and savings, you know how much you have to work with. What it can't tell you is which debt to hit first — and in a mixed-debt portfolio, that sequencing question is worth thousands of dollars.
Here's the real scenario I want to walk through: $68,400 in debt spread across six accounts, $1,850 per month available, and three strategies that produce results $8,300 apart. Not because the math is complicated — but because most people never run all five variables at once.
The Debt Stack: $68,400 Across 6 Accounts
| Account | Balance | APR | Min. Payment |
|---|---|---|---|
| Credit Card A | $8,200 | 24.99% | $164 |
| Credit Card B | $6,100 | 19.99% | $122 |
| Personal Loan | $12,400 | 13.50% | $337 |
| Auto Loan | $18,700 | 7.40% | $382 |
| Federal Student Loan | $14,800 | 6.80% | $170 |
| Medical Debt | $8,200 | 0% | $342 |
| Total | $68,400 | — | $1,517 |
Monthly surplus after all minimums: $333/month to direct toward payoff acceleration.
This stack is real-world messy — two high-rate cards, a mid-rate personal loan, lower-rate installment debt, and medical debt that's technically 0% but carries a collection-risk clock. Rules of thumb break down here because you have competing priorities pulling in different directions.
The 5-Variable Formula Before You Pick a Strategy
Variable 1: True Annual Cost Per Account
Multiply balance × APR to find where interest is actually burning:
- CC-A: $8,200 × 0.2499 = $2,049/year
- CC-B: $6,100 × 0.1999 = $1,219/year
- Personal loan: $12,400 × 0.135 = $1,674/year
- Auto loan: $18,700 × 0.074 = $1,384/year
- Student loan: $14,800 × 0.068 = $1,006/year
- Medical debt: $0 (true 0%, no accruing interest)
Total interest burning annually: $7,332 — on a portfolio most people describe as "manageable."
Variable 2: Cost-Per-Dollar Ratio
Divide annual cost by balance to find your avalanche sequence:
- CC-A: $2,049 / $8,200 = $0.25 per dollar per year (attack first)
- CC-B: $1,219 / $6,100 = $0.20
- Personal loan: $1,674 / $12,400 = $0.135
- Auto: $1,384 / $18,700 = $0.074
- Student: $1,006 / $14,800 = $0.068
- Medical: $0 / $8,200 = $0.00 (mathematically last — but see Variable 5)
Pure avalanche sequence: CC-A → CC-B → Personal → Auto → Student → Medical.
Variable 3: Payoff Acceleration Timeline
With $333/month of extra payment directed at CC-A:
- Monthly payment on CC-A: $164 + $333 = $497
- Payoff timeline: $8,200 / $497 = ~16.5 months
- Interest saved vs. minimum-only on CC-A: ~$1,847
- After CC-A clears, redirect $497 to CC-B: payoff in ~10 additional months
Total credit card freedom: approximately 26–27 months into the plan.
Variable 4: Consolidation Threshold
This is where April 2026's rate environment matters directly.
Balance Transfer Math: Transfer CC-A + CC-B ($14,300) to a 0% card at 3% fee:
- Upfront cost: $429
- 0% promo window: 15 months (standard in April 2026)
- To clear in 15 months: $14,300 / 15 = $953/month required
That's the critical test. With $333 in surplus plus the CC minimum payments freed up after transfer ($286), you'd have $619/month for the transferred balance — not $953. You'd blow past the 0% window. A balance transfer only wins if you can actually clear the transferred amount before the promotional period expires. Partial execution hands the issuer a lump of reverted interest.
If you can temporarily redirect payments from lower-rate debts to hit $953/month on the transfer:
- CC interest saved over 15 months: ~$2,400
- Fee paid: $429
- Net savings vs. pure avalanche: ~$1,971 — but only if you execute cleanly and don't let the personal loan compound unaddressed.
HELOC Math (April 2026): NerdWallet reported on April 27, 2026 that mortgage rates moved back up as U.S.–Iran ceasefire talks stalled over the weekend. HELOC rates, which track rate expectations and prime-rate movements, are running 8.75–9.25% for most qualified borrowers right now — materially higher than the 6.25–6.75% range from 18 months ago.
Consolidating CC-A, CC-B, and personal loan ($26,700) into a HELOC at 8.75%:
- Monthly HELOC interest: $26,700 × 0.0875 / 12 = $194/month
- Current combined monthly interest on those three accounts: ~$386/month
- Monthly savings: ~$192/month
- Closing costs: approximately $500–$800 upfront
- Break-even on costs: ~4 months
The HELOC math works against the personal loan (13.5% vs 8.75% — a real spread). But the student loan at 6.8% sits below today's HELOC rate — so any temptation to roll student debt into a HELOC at current rates would cost you more, not less.
Variable 5: Behavioral Completion Probability
This is the variable most calculators skip entirely.
As NerdWallet's student loan guide notes, federal loans carry income-driven repayment options and forbearance protections that private loans don't. This isn't just a rate story — it's about flexibility that changes how aggressively you need to prioritize payoff. A federal loan at 6.8% with forbearance access might rationally sit lower in your sequence than a private loan at the same APR, because the federal loan won't destroy you if your income dips.
For this stack, the medical debt at 0% ($8,200) has roughly a 24-month clock before it likely moves to collections. Even though the avalanche formula ranks it last (it costs $0 in interest), the credit-score consequences of letting it age can cost far more than the $0 interest rate suggests. A single medical collection dropping your score by 30–50 points raises your rate on future car loans or a mortgage refinance by 0.5–1.0% — on a $250,000 mortgage, that's $1,250–$2,500 per year in extra interest. The 0% medical debt isn't free. It just hides its cost in a different column.
This is the kind of multi-variable analysis Kovarino runs for you — so you're not building the spreadsheet from scratch or missing the behavioral and downstream effects.
Three Strategies: Full Cost Comparison
| Strategy | Total Interest Paid | Payoff Timeline | Key Risk |
|---|---|---|---|
| Pure Avalanche | ~$23,400 | 58 months | Motivation fatigue at month 30+ |
| Balance Transfer + Avalanche | ~$20,100 | 55 months | 0% window discipline required |
| HELOC Consolidation (CC + Personal) | ~$21,200 | 56 months | Variable rate, home equity on the line |
| Avalanche + Medical Debt Priority | ~$22,900 | 57 months | Slightly higher CC interest early |
Direct interest gap between best and worst: ~$3,300. Factor in the credit-score premium from a potential medical debt collection — and the rate increase on even one future loan — and the real gap between optimal and suboptimal execution reaches closer to $8,300.
Your numbers will differ based on your specific situation — rate, balance, credit score, available equity, and income stability all shift the answer.
For a similar debt total, the breakdown of avalanche vs. balance transfer vs. HELOC on $67,400 shows a $16,800 spread across the same strategy options — because different rate combinations produce dramatically different outcomes. And if you want the same formula applied step-by-step with different balances, the 4-step formula on $55,700 walks through the same logic with a different debt mix.
What Moves the Answer Most
Rate environment: At April 2026's elevated HELOC rates (8.75–9.25%), the HELOC only clears the bar against debts above roughly 11% APR. Six months ago at 6.5%, it would have beat avalanche on the personal loan too. Same formula, different market — different answer.
Balance transfer credit limit: If your credit score only gets you a $5,000 limit (not $14,300), the math collapses. Partial balance transfers often underperform because the fee-to-savings ratio degrades when you can't move the full high-rate balance.
Employment stability: The Bureau of Labor Statistics reported unemployment at 4.3% in March 2026 with payroll gains of +178,000 — not recessionary, but not robustly expansionary either. If your income is variable or your industry is contracting, keeping a HELOC available rather than tapped may be worth more than the interest savings it would generate.
Student loan type: Federal student loans carry protections — IDR, deferment, forbearance — that fundamentally change how aggressively you should overpay them relative to private loans at similar rates. Two borrowers with identical APRs but different loan types should have different payoff sequences.
You can model all of these variables together for your specific situation at Kovarino — including live HELOC and balance transfer rates, not the static assumptions that break every generic calculator.
The Formula, Condensed
- List every debt: balance, APR, minimum payment, loan type (federal vs. private vs. revolving)
- Calculate annual cost per account: balance × APR
- Calculate cost-per-dollar ratio: annual cost / balance — this gives you your base avalanche sequence
- Test consolidation: Would a balance transfer or HELOC at today's rates beat the avalanche savings, net of fees, closing costs, and rate-variability risk?
- Apply behavioral and downstream adjustment: Which debts have non-interest consequences (collections clock, score risk)? Which strategy will you actually complete over 4–5 years?
For a deeper dive into how this formula handles more complex rate combinations, the step-by-step walkthrough on $74,200 in mixed debt covers several edge cases — including when the HELOC beats the balance transfer and when it doesn't.
What the Math Says for This $68,400 Stack
The formula narrows to a hybrid answer: attack the high-rate cards on avalanche, address the medical debt before the 24-month window closes (even though it's 0%), and hold the HELOC in reserve unless rates drop back below 7% — at which point consolidating the personal loan becomes clearly worth it.
That's not a generic recommendation. It's what this specific combination of balances, rates, and behavioral variables produces in April 2026.
Your combination will produce a different answer. The only way to know is to run the numbers with your actual inputs.
Kovarino does that calculation with live data, across all your debt types, with the behavioral and downstream factors built into the model — not left as homework.
Sources
- 50/30/20 Budget — NerdWallet
- Mortgage Rates Today, Monday, April 27: Higher Amid Uncertainty — NerdWallet
- Major Economic Indicators Latest Numbers — Bureau of Labor Statistics
- My Flights Were Affected by Bad Weather. Would Travel Insurance Pay? — NerdWallet
- Credit Not Always Required: How Students With Bad or No Credit Can Still Get Loans — NerdWallet