About BestConvertCalc

Fast, free calculators for the things that actually matter — your mortgage, your taxes, your retirement. No login. No ads. No data collected. Just math that works.

What we built and why

Most calculator sites are cluttered with ads, slow to load, and designed to keep you on-site rather than give you the answer quickly. Some require accounts. Others send your inputs to their servers. We built BestConvertCalc as the opposite: a clean, fast, open-source-in-spirit alternative that respects your time and your privacy.

Every calculator on this site runs entirely in your browser. The numbers you enter never leave your device. There is no account to create, no email to confirm, no subscription to buy. We make money through optional advertising in the future — but the calculators themselves will always be free and unblocked.

Our principles

What's here

BestConvertCalc covers six areas:

Finance — mortgage, compound interest, amortization, auto loan, personal loan payoff, savings goal, ROI, break-even, retirement planner, capital gains, and more.

Health — BMI, calorie needs (TDEE), body fat, ideal weight, pregnancy due date, and unit-based health conversions.

Tax — federal income tax (2024/2025 brackets), self-employment tax, quarterly estimated tax, W-2 vs. 1099 comparison, capital gains tax, sales tax by state, and a full tax tracker.

Freelance — freelance hourly rate, hourly-to-salary and salary-to-hourly converters, paycheck estimator, and a freelance income and expense tracker with quarterly tax reminders.

Converters — length, weight, temperature, speed, shoe sizes, clothing sizes, and ring sizes across major international systems.

Everyday — tip, percentage, percentage change, discount, scientific notation, age, date difference, GPA, random number, square footage, and paint coverage.

Accuracy and limitations

We work hard to keep tax brackets, rates, and formulas current for each tax year. That said, tax law is complex and changes frequently. Our calculators provide estimates for planning purposes — they are not a substitute for advice from a licensed tax professional, financial advisor, or accountant.

Federal tax calculations use IRS-published bracket tables for 2024 and 2025. State and local taxes are not included in most calculators. Health calculations use general population formulas (Mifflin-St Jeor, BMI, etc.) and are not medical advice.