About GM Calculator
GM Calculator is a collection of 41 free online calculators covering marketing, finance, health, and math. Our mission is simple: make powerful calculation tools accessible to everyone, completely free, with no sign-up required.
Our Mission
We believe that essential calculation tools should be free, fast, and private. Whether you're a marketer calculating ROAS, a student figuring out compound interest, or someone tracking their health metrics — you shouldn't need to create an account, pay a subscription, or navigate through intrusive ads to get accurate results.
Every calculator on GM Calculator is built with verified formulas from medical, financial, and mathematical standards. Results update instantly as you type, and all calculations happen in your browser — your data never leaves your device.
Our Story
GM Calculator was born from a simple frustration: too many websites charge for basic calculators, require annoying sign-ups, or bombard you with intrusive ads. We wanted to create something different — a place where anyone could get instant, accurate calculations without any barriers.
Our team of developers, mathematicians, and designers worked together to build 41 powerful calculators that are both accurate and easy to use. We focused on quality and comprehensiveness, ensuring each calculator serves a real need and provides genuine value to users.
Our Values
100% Free
No paywalls, no premium tiers, no hidden costs
Instant Results
Real-time calculations, no loading delays
Privacy First
Your data never leaves your browser
Accuracy Guaranteed
Verified formulas from industry standards
Our Tools
We offer 41 specialized calculators across four categories:
- Marketing (14): ROAS, break-even ROAS, target ROAS, CPM, CPC, CTR, conversion rate, CAC, LTV:CAC, ROI, marketing budget, CPA, customer retention, churn rate
- Finance (8): Simple interest, compound interest, margin & markup, loan, mortgage, savings goal, debt payoff, investment return
- Health (6): BMR, TDEE, body fat, water intake, weight & height, health dashboard
- Math (13): Percentage, fraction, grade & GPA, statistics, percentage increase, ratio, tip, discount, date, equation solver, quadratic solver, Pythagorean theorem, scientific notation
Our Expert Team
Every calculator and guide on GM Calculator is reviewed by subject-matter experts with verified credentials. Our team ensures accuracy, relevance, and trustworthiness across all our content.
Dr. Sarah Mitchell
Health & Nutrition Specialist
Dr. Sarah Mitchell is a registered dietitian (RD) and certified exercise physiologist (ACSM-CEP) with over 12 years of clinical and research experience. She holds a Ph.D. in Nutritional Sciences from the University of Illinois and has published peer-reviewed research on metabolic rate estimation, body composition analysis, and evidence-based weight management strategies. Sarah has worked with athletes, clinical populations, and general wellness clients, bringing a deep understanding of how BMR, TDEE, and body composition formulas perform in real-world settings.
Credentials & Education
- ✓Ph.D. Nutritional Sciences — University of Illinois
- ✓Registered Dietitian (RD) — Commission on Dietetic Registration
- ✓ACSM Certified Exercise Physiologist
- ✓Published researcher — 15+ peer-reviewed papers on metabolism and nutrition
Areas of Expertise
James Rodriguez, CFA
Finance & Investment Analyst
James Rodriguez is a Chartered Financial Analyst (CFA) charterholder with over a decade of experience in investment research, portfolio management, and personal financial planning. He holds an MBA from Wharton School of Business and previously worked as a senior analyst at Goldman Sachs. James specializes in making complex financial concepts accessible, including compound interest calculations, margin analysis, and investment return metrics. His work has been featured in Forbes and The Wall Street Journal.
Credentials & Education
- ✓CFA Charterholder — CFA Institute
- ✓MBA Finance — Wharton School of Business, University of Pennsylvania
- ✓Former Senior Analyst — Goldman Sachs
- ✓Featured in Forbes, The Wall Street Journal, and Bloomberg
Areas of Expertise
Alex Chen, MBA
Digital Marketing Strategist
Alex Chen is a digital marketing strategist and performance marketing specialist with over 8 years of experience managing multi-million dollar advertising budgets across Google Ads, Meta Ads, and programmatic platforms. He holds an MBA from Stanford Graduate School of Business and previously led growth marketing at two Y Combinator-backed startups. Alex has deep expertise in ROAS optimization, customer acquisition cost modeling, and marketing analytics. He regularly speaks at marketing conferences including SMX, HeroConf, and Meta Marketing Summit.
Credentials & Education
- ✓MBA — Stanford Graduate School of Business
- ✓Google Ads Certified Professional
- ✓Meta Certified Marketing Science Professional
- ✓Speaker at SMX, HeroConf, and Meta Marketing Summit
Areas of Expertise
Emily Watson, M.Ed.
Mathematics Educator
Emily Watson is a mathematics educator with over 15 years of experience teaching algebra, statistics, and applied mathematics at the high school and college levels. She holds a Master of Education from Columbia University Teachers College and has designed math curricula used by schools across the United States. Emily is passionate about making math accessible and practical, helping students and professionals understand everything from basic percentages to statistical analysis. She has been recognized by the National Council of Teachers of Mathematics for her innovative approaches to math education.
Credentials & Education
- ✓M.Ed. Mathematics Education — Columbia University Teachers College
- ✓National Board Certified Teacher — Mathematics
- ✓NCTM Award for Innovation in Mathematics Education
- ✓15+ years teaching algebra, statistics, and applied math
Areas of Expertise
Get in Touch
Have a question, suggestion, or found a bug? We'd love to hear from you.