Calculator Formulas
All SmartRates calculators use industry-standard financial formulas:
• Mortgage & Loan Payments: M = P·r(1+r)ⁿ / [(1+r)ⁿ−1], where P = principal, r = monthly rate, n = total payments • Compound Interest: FV = PV·(1+r/12)^(12·t) + PMT·[(1+r/12)^(12·t)−1]/(r/12) • Retirement Projections: Future value of ordinary annuity with monthly compounding • Federal Income Tax: 2026 IRS marginal brackets, standard deduction, and FICA rates • 401(k) Limits: 2026 IRS elective deferral limit ($23,500; $31,000 age 50+)
All tax data is sourced directly from IRS publications (Rev. Proc. 2025-XX and related guidance). We update calculators as soon as new IRS data is released each fall.
Credit Card Evaluation
We evaluate credit cards across the following criteria:
• Rewards Rate — headline earn rate on primary spend categories • Annual Fee — net cost after factoring in recurring credits • Welcome Bonus — value of signup bonus relative to spend requirement • APR Range — regular variable APR low and high ends • Benefits — travel protections, cell phone coverage, lounge access • Credit Score Requirement — estimated minimum FICO score to qualify
Data is sourced from issuer websites and verified against NerdWallet, Bankrate, and The Points Guy. APR ranges reflect the latest disclosed variable rates and change with the prime rate.
Loan Evaluation
Personal and auto loans are evaluated on:
• APR Range — lowest and highest advertised rates (lowest typically for excellent credit) • Loan Amount Range — minimum and maximum available • Term Options — shortest to longest available repayment period • Origination Fee — upfront fee deducted from proceeds • Minimum Credit Score — approximate FICO required to qualify • Funding Speed — typical time from approval to fund receipt • Special Features — co-signer options, direct creditor pay, hardship programs
APR ranges are sourced from lender websites and updated quarterly. Actual rates are personalized and may differ.
Brokerage Account Evaluation
Online brokers are evaluated on:
• Commission Schedule — stock, ETF, and options trade costs • Account Minimum — minimum deposit to open an account • Account Types — individual, IRA, joint, trust, etc. • Platform Quality — research tools, charting, mobile app • Special Features — fractional shares, crypto, paper trading, margin rates • Customer Service — availability and channel options
Data is sourced from broker fee schedules and updated when brokers announce changes. Commission structures evolve; always verify the current fee schedule with the broker before opening an account.
Editorial Independence
SmartRates does not earn affiliate commissions or referral fees from "Apply" or "Open Account" links. We have no commercial relationships with the issuers, lenders, or brokerages listed on this site.
The site is supported by display advertising (Google AdSense). Advertising revenue does not influence which products are listed, how they are ranked, or what data we report. Products are ranked solely on the evaluation criteria described above.
Update Frequency
• Tax calculators: Updated annually when IRS releases inflation adjustments (typically October–November for the following tax year) • 401(k)/IRA limits: Updated as soon as IRS announces contribution limits • Credit card data: Reviewed quarterly; material changes (APR shifts, fee changes, bonus updates) updated within 30 days of notification • Loan rate ranges: Reviewed quarterly • Brokerage data: Updated within 30 days of any broker announcement
The "Last updated" date on each data source is available in data/sources.ts in our source files.