How to Calculate Debt Consolidation Savings on $24,500: Personal Loan vs HELOC vs Balance Transfer vs 401(k) Loan (September 2026)
Say you're carrying $24,500 across credit cards at 24% APR and sending $700 a month toward it. That feels like real progress. The math says otherwise: month one, about $490 of that $700 is interest. Only $210 touches the balance.
Consolidating looks like the obvious move. But a personal loan, a HELOC, a 0% balance transfer, and a 401(k) loan all look cheap on the marketing page and behave very differently once fees, payoff speed, and your own credit profile go in.
This guide shows the formulas and a full worked example. Every rate, fee, and limit below is an example input I chose, not a quote from any lender. Your numbers will differ based on your specific situation, and the point of the post is to show which inputs change the answer.
Step 1: Price the debt you have now
The payoff time on a fixed payment is:
n = −ln(1 − r × B ÷ P) ÷ ln(1 + r)
Here r is the monthly rate, B is the balance, and P is the payment.
For the baseline, r = 24% ÷ 12 = 2%, B = $24,500, and P = $700:
- 1 − (0.02 × 24,500 ÷ 700) = 0.30
- n = −ln(0.30) ÷ ln(1.02) ≈ 60.8 months
- Total paid ≈ $42,553, so interest ≈ $18,053
That number is what every consolidation option has to beat.
Step 2: Normalize the term by fixing the budget
Comparing a 36-month loan to a 60-month loan to a 21-month promo is apples to oranges. The shorter term looks worse on monthly payment and better on interest, and neither tells you much.
The cleaner fix is to hold your monthly cash outflow constant at $700 and measure the payoff time and total cost each option produces. Nothing gets to look cheaper just by stretching the term.
Here are the example inputs:
- Personal loan: 12.5% rate, 5% origination fee taken from proceeds, so you borrow $25,789 to net $24,500.
- Balance transfer: 3% fee added to the balance ($25,235), 0% for 21 months, then 22% APR. This assumes you're approved for a limit that large, which is the big "if."
- HELOC: 8.5% variable rate, $600 in closing costs rolled in ($25,100 borrowed).
- 401(k) loan: 9.5% interest paid back to your own account, $75 fee ($24,575 borrowed).
Step 3: Effective APR, total cost, and NPV
| Option | Effective APR | Months to payoff at $700 | Total cash paid | Fees + interest | NPV cost at 6% |
|---|---|---|---|---|---|
| Keep the cards | 24.0% (26.8% compounded) | 60.8 | $42,553 | $18,053 | $12,128 |
| Personal loan | ≈15.4% | 46.8 | $32,725 | $8,225 | $4,593 |
| Balance transfer | ≈6.3% | 38.8 | $27,132 | $2,632 | ≈$110 |
| HELOC | ≈9.9% | 41.5 | $29,057 | $4,557 | $1,687 |
| 401(k) loan | 9.5% (paid to yourself) | 41.3 | $28,910 | $4,410 | ≈$0 to $2,200 (see below) |
Some notes on how to read it:
- Effective APR is the rate that makes the money you actually received ($24,500) equal the present value of your payments. It's the same idea as the calculation in the 5 calculations that reveal your best debt consolidation option.
- The personal loan's effective APR (15.4%) sits well above its 12.5% rate because the 5% fee is a fixed lump. The faster you pay, the higher the fee's effective APR gets. That's counterintuitive and easy to miss.
- NPV cost discounts every payment at 6% a year, which stands in for what your money could earn elsewhere. Swap in your own rate.
- The balance transfer's NPV lands near zero because 21 months of 0% is worth a lot in present-value terms. But it only works if the promo limit and the payoff discipline both hold.
This is the kind of side-by-side Tevarindo runs for you, so you don't have to build the spreadsheet yourself.
The same personal loan can cost $5,000 or $14,600
Personal loan pricing depends on your credit profile. Here is the same product at $700 a month under three example profiles:
| Profile (example) | Rate / fee | Borrowed | Months | Fees + interest |
|---|---|---|---|---|
| Strong credit | 9.5% / 2% | $25,000 | 42.1 | $4,998 |
| Middle | 12.5% / 5% | $25,789 | 46.8 | $8,225 |
| Weaker credit | 17.5% / 8% | $26,630 | 55.9 | $14,616 |
For the weaker profile, consolidating still saves about $3,400 against the cards' $18,053. That's real, but it's a third of what the strong profile saves. Any calculator that shows one "personal loan rate" for everyone is averaging away the thing that matters most.
Earlier posts in this series make the same point at different balances. See when the lower rate actually costs you more for the mechanics.
Where this week's data fits (and where it doesn't)
Four sources from the last few days are worth reading against the math.
Inflation. The Bureau of Labor Statistics' "Major Economic Indicators Latest Numbers" page shows CPI at +0.4% in August 2026. Annualizing one month is crude, but 1.004¹² ≈ 1.049, or about 4.9% a year if that pace held. This matters for anything variable-rate, since rate-setters watch inflation.
Jobs and wages. The same page lists unemployment at 4.1%, payroll employment at +162,000 (preliminary), and average hourly earnings up $0.10 (preliminary). Two takeaways:
- A dime an hour is about $208 a year for a 2,080-hour worker, before taxes, or roughly $17 a month.
- Compare that to the HELOC. If its rate rises one point, the same $700-a-month plan costs about $580 more in total (see the sensitivity below), which is about $14 a month. One rate point can cancel out roughly one dime of raise.
Mortgage rates. NerdWallet's "Mortgage Rates Today, Friday, September 18: No Change" says rates took a breather while bond markets digest this week's Fed news. That's useful context, but it isn't a HELOC quote. HELOCs are typically variable, so a flat day in mortgage rates tells you little about where yours will be in 18 months. I've linked a related walkthrough on flat mortgage rates with CPI up 0.4% if you want the parallel case.
Unemployment and your 401(k). At 4.1% unemployment, roughly 1 in 24 workers in the labor force is out of work. Averages say nothing about your job, but that's the backdrop for the 401(k) loan below.
The 401(k) row needs its own math
Interest on a 401(k) loan goes back into your own account, so "cost" needs care. Using the example loan ($24,575 borrowed, 9.5%, $700 a month):
- Interest paid to yourself: about $4,335
- If the money had stayed invested at 7%, you'd have forgone about $3,194. So you come out roughly $1,066 ahead after the $75 fee.
- If the market returned 12%, you'd have forgone about $5,476, so you're roughly $1,216 behind.
- Tax drag: in a traditional account you repay with after-tax dollars, and that interest is taxed again at withdrawal. At an example 22% marginal rate, that's about $954.
Adding the tax drag puts the economic cost at roughly $0 to $2,200. That looks like the cheapest option in the table. The risks aren't in the average case:
- Lost match. If you pause contributions to afford the payment and give up an example $150-a-month match, that's 41.3 × $150 ≈ $6,195.
- Job separation. Many plans require the balance back quickly if you leave, and an unpaid balance can be treated as a taxable distribution, possibly with a penalty.
For a fuller look at these tail risks, see the hidden cost gap between a 0% balance transfer, personal loan, HELOC, and 401(k) loan.
Credit score impact: the part that's hardest to price
None of this week's sources quantify score changes, and the effect varies by profile, so I won't invent a point number. What you can model is utilization:
- Suppose your cards have $30,000 in total limits (an example). $24,500 owed is about 82% utilization. Paying the cards to zero with any of the four options drops that sharply, at least until you run balances back up.
- A balance transfer puts $25,235 on a new card. If its limit is $25,500 (an example), that card sits at about 99% utilization. Scoring models weigh per-card and overall utilization differently, so ask how yours treats it.
- A personal loan adds an installment account and a hard inquiry.
- HELOC reporting varies by lender and scoring model. Ask before you apply.
If you expect to apply for a mortgage or auto loan in the next year, treat score effects as a real line item in your comparison.
What flips the ranking
Here is how the ranking moves when one input changes:
| Change | Effect on the example |
|---|---|
| HELOC rate rises 8.5% → 9.5% | Cost goes from $4,557 to about $5,140 (+$580) |
| Balance transfer post-promo APR is 29.99% instead of 22% | Cost goes from $2,632 to about $3,584 (+$950) |
| Budget rises from $700 to $900 a month | HELOC cost falls to about $3,560, a saving of ~$1,000. The cards fall from $18,053 to about $11,240, a saving of ~$6,800 |
| Balance transfer at $900 a month | Cost falls to about $1,245 |
| Balance transfer paid off in 21 months ($1,202 a month) | Cost is just the $735 fee |
The third row is the surprising one. Extra monthly cash helps the worst option most. That's why consolidation and cash flow are substitutes, not separate decisions.
Three side conversations that change the math
Extra income. NerdWallet's "Quiz: What's the Best Way to Make Money?" is a reminder that the payment side of the equation isn't fixed. If a side hustle adds even $200 a month (my example), the table above changes.
Reward points. NerdWallet's "How I Earned 1 Million Points With My Family Cruise Booking" is a fun read. But run the math on the cards you're carrying. If you value points at 1 cent each (my assumption, not NerdWallet's), 1 million points is about $10,000. At the baseline's first-month interest of $490, that's about 20 months of interest. Chasing rewards while paying 24% rarely pencils out.
"Free money" with strings. NerdWallet's "Locked Out: Should You Take 'Free Money' to Buy a Home?" says homebuying assistance can lower upfront costs but needs a look at the trade-offs first. That's the right instinct for a 0% offer too. The 3% transfer fee and the post-promo rate are the strings.
A five-minute checklist for your own numbers
- Balance and rate on every card, and the total monthly payment you can honestly sustain.
- Baseline payoff time and interest using the formula above.
- Rate and fee quotes for each option you'd actually qualify for. Get personal loan quotes on a soft-pull basis where offered.
- Effective APR at your real payoff pace, not the advertised term.
- Your discount rate for the NPV, meaning what spare cash could earn or the debt you'd otherwise carry.
- Sensitivities: the HELOC rate up a point, the balance transfer's post-promo rate, a missed month, a job change.
- Credit timing: any mortgage or auto loan on the horizon.
You can model this for your specific situation at Tevarindo. It handles the term normalization, NPV discounting, and effective APR math for all four options side by side.
The bottom line
With these example inputs, the balance transfer wins if the limit, the payoff discipline, and the post-promo rate all hold. The HELOC is second, with the house as collateral and a variable rate. The personal loan is the most predictable and ranges from about $5,000 to $14,600 depending on credit. The 401(k) loan looks cheap on paper and carries the sharpest tail risks.
Change the credit profile, the budget, or the HELOC rate, and the order changes. That's why a rule of thumb can't settle this, and why running your own numbers is worth an evening before you sign anything.
When you're ready, put your balances and quotes into Tevarindo and compare the four options on the same footing. The math should speak for itself, and your inputs are what make it yours.
Sources
- Major Economic Indicators Latest Numbers — Bureau of Labor Statistics
- How I Earned 1 Million Points With My Family Cruise Booking — NerdWallet
- Locked Out: Should You Take ‘Free Money’ to Buy a Home? — NerdWallet
- Quiz: What’s the Best Way to Make Money? — NerdWallet
- Mortgage Rates Today, Friday, September 18: No Change — NerdWallet