PennyRatio is a free suite of personal finance calculators built to help you make sense of retirement, taxes, borrowing, and savings—without complex setup or account sign-ups. Key Tools & Features: US Tax & Retirement: Plan early withdrawals with the US 72(t) SEPP tool or model take-home earnings with the US Paycheck Tax calculator. Savings & Borrowing: Plan ahead using Compound Interest, Mortgage, Rent vs. Buy, Debt Payoff, and Auto Loan calculators.