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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Lifestyle
Delivery vs Cooking Cost Calculator
Compare DoorDash/Uber Eats delivery cost vs. cooking at home. 2026 typical 69-83% markup vs in-restaurant. Service fee + delivery fee + tip + menu markup adds 15-25%.
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Lifestyle
Credit Card Rewards vs BNPL Calculator
Compare paying with rewards credit card vs Buy Now Pay Later (Klarna, Affirm, Afterpay). Cashback earnings vs BNPL interest, 22.11% credit card APR, CFPB BNPL TILA protections.
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Lifestyle
Overseas Shopping Total Cost Calculator
Calculate true total cost of overseas online purchases. $800 de minimis SUSPENDED Aug 2025 (China May 2025). All shipments now incur duty + 10% Trump tariff + brokerage + state tax.
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Lifestyle
Rent vs Buy Calculator
Compare buying a home vs renting using true monthly costs. Freddie PMMS 6.30% mortgage rate, 1.10% property tax, $2,490 home insurance, PMI, plus the famous 5% rule.
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Lifestyle
Lifetime Commute Time Waste Calculator
Calculate total hours, days, and years of your life spent commuting. US Census 2024 average 27.2 min one-way. Plus opportunity cost at your hourly rate.
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Finance
CD Maturity Calculator
Free CD maturity calculator. Project the maturity value of a US bank CD by APY and term, including federal income tax on interest. Compare to high-yield savings or recurring savings.
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Lifestyle
US Natural Gas Bill Calculator
Calculate residential natural gas bill from therms × rate + fixed charge. EIA Jan 2026 US average $1.39/therm ($13.94/Mcf). Annual heating cost projection by state.
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Real Estate
Security Deposit Opportunity Cost Calculator
Free security deposit opportunity cost calculator. Compute the lost return on your security deposit if it had been invested elsewhere — typical 1-3% per year hidden cost.
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Real Estate
Rental Scam Risk Checker
Free rental scam risk checker using FTC, BBB, FBI IC3 fraud markers. Score a prospective rental on 10 red flags — wire transfer requests, no in-person tour, advance fees, fake landlords.
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Lifestyle
US Water Bill Calculator
Calculate residential water bill from gallons used × rate + fixed charges. 2026 US average $49-$78/month for family of 4. CA $77, WV $91 highest; VT/WI/NC $18-$20 lowest.
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Insurance
Social Security Benefit Estimator
Free Social Security benefit estimator using the SSA PIA formula and current bend points. Project your monthly benefit at age 62, FRA (67 for those born 1960+), or 70.
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Insurance
ACA Marketplace Premium Estimator
Free ACA Marketplace premium estimator. Project your monthly premium and Premium Tax Credit (subsidy) by income and household size — based on Federal Poverty Level (FPL) thresholds.
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