Editorial principles
- Every formula and figure is verified against official sources (laws and public agency notices).
- When rates change, the calculator and its guide content are updated together.
- Reported errors are fixed as soon as they are confirmed.
Calculators by Sin Dongho (178)
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Finance
Personal Loan Calculator
Free personal loan calculator using current Federal Reserve G.19 average rates. Get monthly payment, total interest, and amortization for amortizing, equal-principal, and interest-only loans.
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Finance
Compound Interest Calculator
Free compound interest calculator. Project the future value of savings with daily, monthly, quarterly, or annual compounding. Add monthly contributions to model HYSA, CD, or 401(k) growth.
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Lifestyle
US Electricity Bill Calculator
Calculate residential electricity bill: kWh × rate + fixed charge. EIA April 2026: US average 17.65¢/kWh. Hawaii highest 43¢, North Dakota lowest 11.64¢. Annual cost projection.
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Finance
Loan Prepayment Savings Calculator
Calculate net savings from loan prepayment vs holding to maturity. Most US loans NO penalty (TILA/Dodd-Frank QM). Compare interest saved minus penalty + alternative investment return.
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Finance
Loan Comparison Calculator
Compare two loan repayment methods: standard amortizing (level payments, more interest) vs equal-principal (declining payments, less interest). See total cost difference.
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Finance
Mortgage Refinance Savings Calculator
Calculate net savings from refinancing your mortgage. Compare current vs new APR, factor in closing costs (2-5%), and find break-even month. Rule of thumb: 0.75-1% rate drop minimum.
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Finance
Interest Rate Impact Calculator
See how a 1% rate change affects your loan total cost. Compare scenarios at -1%, current, +1%, +2%. Critical for ARM borrowers facing rate reset and refinance decision-making.
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Finance
Loan Term Comparison Calculator
Free loan term comparison calculator. Compare a longer-term loan to a shorter alternative side by side — see how much you save in total interest by paying more each month.
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Finance
Personal Loan vs Credit Card Calculator
Compare personal loan amortization vs credit card revolving debt. Personal loan 13.45% (3yr) / 17.79% (5yr) vs credit card 23.77% APR. Debt consolidation savings calculator.
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Real Estate
US Security Deposit Calculator
Free US security deposit calculator. Check your state's legal maximum security deposit, refund deadline, and itemized deduction rules. Each state regulates differently.
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Lifestyle
Car vs Public Transit Cost Calculator
Compare driving vs public transit commute costs. AAA May 2026 gas $4.54/gal, US fleet avg 27 MPG, AAA total ownership $11,577/yr. Daily parking + monthly pass options.
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Lifestyle
Subscription Total Cost Calculator
Add up all your subscriptions to see the real monthly and annual cost. Avg American spends $84-$219/mo on subs. Netflix $17.99, Disney+ $16.99, Max $18.49, Spotify $18.
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