以下のガイドはまだ日本語に翻訳されていないため、英語で表示しています。計算機自体はすべて日本語に対応しています。
この計算機の使い方
- Choose whether you want to know the payoff time or the required monthly payment.
- Enter your current balance and the card's APR.
- Enter your planned monthly payment, or the number of months you want to be debt-free in.
- Compare the result with paying only the minimum to see how much interest you can save.
計算式
Card interest is charged monthly at APR ÷ 12 on the balance. With a fixed payment P, the number of months is solved from the amortization formula. The minimum-payment comparison assumes the issuer requires interest plus 1% of the balance, with a $25 floor.
n = −ln(1 − r × B / P) / ln(1 + r), with r = APR / 12
Minimum payment ≈ max(interest + 1% × balance, 25)
Example
- Balance $6,000 at 22.9% APR, paying $250 a month: r ≈ 1.908% per month.
- First month's interest ≈ $114.50, so only about $135.50 reduces the balance.
- It takes about 33 months and roughly $2,200 in interest to pay off.
よくある質問
Why do minimum payments take so long?
Minimum payments are set mostly to cover interest, so the balance falls very slowly. Paying a fixed, higher amount can save years and thousands in interest.
Should I transfer my balance?
A 0% balance transfer can save interest if you can repay within the promotional period. Remember to include the transfer fee, typically 3–5%.
Does this include new purchases?
No. The calculation assumes you stop using the card while paying it off.