Total Debt Cost Calculator

What this calculator does

Most debt calculators focus on a single loan or on a chosen payoff strategy. This one answers a simpler question: across the debts being paid down right now, what is the total amount that will leave the account before they all clear, assuming each is paid at a fixed monthly amount until its scheduled end? The total is the headline figure; the per-debt breakdown shows how each contributes to it.

How the math works

The calculation is the sum of monthly payment × months remaining for each debt:

Total = Σ (Monthly_i × Months_i)

The output also shows the longest of the three terms, which marks how many months the borrower will still be making payments on at least one debt under the entered schedule. The math assumes payments hold constant — no missed months, no overpayments, no rate changes that would alter the monthly figure.

Worked example

Three debts: 200 monthly for 36 months, 100 monthly for 24 months, 50 monthly for 12 months. The arithmetic: 200 × 36 = 7,200; 100 × 24 = 2,400; 50 × 12 = 600. Combined total: 10,200. The 36-month term is the longest, so the borrower remains on at least one payment schedule for three more years. The breakdown clarifies which debt contributes most to the total: in this example debt 1 accounts for about 71% of the lifetime cost despite carrying the smallest number of months.

What this calculation does not capture

The calculator assumes a fixed monthly payment for the full remaining term on each debt. It does not capture interest rate changes mid-term, missed or partial payments, additional borrowing during the period, fees added to the principal, prepayment penalties, balance transfers, or promotional rates that revert. It also does not split out the interest portion separately — it shows total payments. To see interest in isolation for any individual debt, the standalone debt-payoff or remaining-balance calculators handle that decomposition. The figure is best read as the planned cash outflow under the current schedule, not a guaranteed actual outcome.

Reading the output

The headline figure is the sum across all three debts under the entered schedule. The per-debt totals reveal where the bulk of the cost sits, which is often counter-intuitive: a small monthly figure carried over many years can match or exceed a larger monthly figure on a shorter schedule. The longest-term figure is the time horizon the borrower remains in the schedule. Three numbers together — total, per-debt mix, and time horizon — give a fuller picture than the headline alone.