Loan & Debt Calculator Pack
A 5-step chain: auto loan, plan comparison, prepayment, take-home pay — know the numbers before you borrow.
Debt itself is not scary — borrowing while only looking at the monthly payment is. This pack breaks borrowing into five steps: monthly cost, plan comparison, prepayment math, take-home pay, and a debt-ratio sanity check.
5 tools · follow the steps
Use in this order
- 1Loan Comparison CalculatorEqual payment vs equal principal — total interest compared
Step 1 · Compare plans
Compare rates and terms side by side — total cost gaps are bigger than intuition suggests.
- 2Auto Loan CalculatorCar payment, total cost and purchase tax
Step 2 · Auto loan
Auto loans hide fees in headline rates — compute the true annualized cost.
- 3Early Mortgage Payoff CalculatorShorter term vs lower payment — interest saved
Step 3 · Prepayment
Quantify interest saved and compare against investment returns before prepaying.
- 4Net Pay CalculatorGross salary, social insurance, tax to net pay
Step 4 · Net pay
Debt ratio is measured against take-home pay, not gross — check net first.
- 5Take-Home Pay CalculatorSocial insurance, tax and net monthly salary
Step 5 · Salary breakdown
Break down social insurance, housing fund and tax to see your true monthly cash base.
Related Guides
How to Compare Loans: Total Interest, APR & Terms
Never compare monthly payments — compare APR and total repayable. A 5-year loan at 4.5% beats a 7-year at 4.0% on total cost despite the higher payment. Includes the full comparison framework: rate type, fees, prepayment terms and total interest.
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Early Mortgage Payoff: Shorten Term or Lower Payment?
Prepaying $1M/30yr/3.0% by $200k in year 3 saves ~$180k interest (term-shortening mode). Best timing is the first third of the loan when payments are interest-heavy. Covers both prepayment modes, penalty clauses and the invest-vs-prepay decision.
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Equal Payment vs Equal Principal: Which Saves More?
Equal payment (annuity) keeps monthly payments constant; equal principal costs less interest overall but starts higher. Real test on a $1M loan: $67k interest difference over 30 years. Formulas, comparison tables, rate sensitivity analysis and a decision tree inside.
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Auto Loan Payment: Down Payment, Rates & the 0% Trap
Payment follows the same annuity formula as mortgages. $150k over 3 years at 4% → $4,429/mo. Dealer "0% interest" deals often hide financing fees or a higher car price. Includes rate tables, total cost comparisons and the fee checklist.
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Take-Home Pay: Social Insurance, Housing Fund & Income Tax
Gross ¥10,000/month takes home roughly ¥7,500–8,000 after social insurance (~10.5%), housing fund (5–12%) and income tax. Includes the full deduction formula, 2025 social insurance base caps, special additional deductions and year-end bonus tax strategy.
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Net Pay: Gross-to-Net Breakdown (Social Insurance + Tax)
Net = gross − social insurance (pension 8%, medical 2%, unemployment ~0.5%) − housing fund (5-12%) − income tax. ¥15k gross with 12% fund → ~¥11.5-11.8k net. Includes the contribution-base cap/floor rules and why the same gross nets differently by city.
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FAQ
What debt-to-income ratio is safe?
A common red line: payments under 1/3 of take-home pay, and under 1/2 including all debts. Above 50% resilience gets thin.
Is zero-interest auto financing free?
Often not — fees or forced add-ons replace interest. Compare total cost of financing vs paying cash.
Invest spare cash or pay down debt?
Compare two things: your real loan rate vs after-tax investment return. If returns are reliably below the loan rate, prepaying is a risk-free return at the mortgage rate.