Free Online Calculator — ROAS, BMR, Compound Interest & 41 Free Tools
Marketing: $1,500 revenue from $400 ad spend → ROAS of 3.75×. Finance: $10,000 at 5% for 10 years → $6,416 in compound interest. Health: 180 lbs, 5'10", age 30, male → BMR of 1,715 cal/day.
Math: 350 total points across 4 classes → GPA of 3.50. Whether you're optimizing ad budgets, planning retirement, tracking fitness goals, or solving homework problems, GM Calculator gives you instant, accurate results — no sign-up, no ads, no data tracking.
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Why GM Calculator?
We built a better calculator experience — no clutter, no noise, just answers.
Instant Results
No page reloads, no waiting. Results update as you type — just like a spreadsheet.
Purpose-Built Tools
Each calculator is focused on one task. No feature bloat, no confusing options.
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Your numbers never leave your device. No sign-up, no tracking, no data collection.
Works Everywhere
Desktop, tablet, phone — same great experience. Built with modern responsive design.
What You Can Calculate with GM Calculator
GM Calculator gives you 41 free online calculators across four essential categories — marketing, finance, health, and math. Every tool is designed for instant results with no sign-up, no data tracking, and no hidden fees. Here is what you can calculate right now:
📊 Marketing Metrics
ROAS — find your return on ad spend with revenue and cost inputs. Calculate CPM, CPC, CTR for campaign optimization. Track CAC and LTV:CAC ratios to measure customer profitability. Use the Break Even ROAS calculator to find your minimum profitable ad ratio. Plan budgets with the Marketing Budget Calculator. Example: $1,500 revenue from $400 ad spend = 3.75× ROAS (excellent for e-commerce).
💰 Finance & Investing
Compound Interest — project growth with any rate, term, and compounding frequency, adjusted for inflation. Calculate loan payments, mortgage affordability, and amortization schedules. Use the Savings Goal Calculator to plan for retirement, a home down payment, or an emergency fund. Compare debt payoff strategieswith snowball vs. avalanche methods. Example: $10,000 at 7% compounded monthly for 10 years grows to $20,097.
❤️ Health & Fitness
BMR — calculate basal metabolic rate using Mifflin-St Jeor, Harris-Benedict, and Katch-McArdle formulas. Use the TDEE Calculator to find total daily energy expenditure and set calorie targets for weight loss, muscle gain, or maintenance. Estimate body fat percentage with the US Navy method, calculate daily water intake needs, and find your ideal weight range. Example: 180 lbs, 5'10", age 30, male = BMR of ~1,715 calories per day.
📐 Math & Statistics
Percentage Calculator — 6 modes including what is X% of Y, percentage increase, decrease, and difference. Solve fractions, ratios, and proportions step by step. Calculate grade point average (GPA) from points or letter grades. Compute mean, median, mode, and standard deviation with the Statistics Calculator. Solve linear and quadratic equations, apply the Pythagorean theorem, and convert scientific notation. Example: 350 total points across 4 classes = GPA of 3.50.
Each calculator includes the formula behind it, real-world examples, and expert tips. All 41 tools are backed by verified standards — from the Academy of Nutrition and Dietetics for health formulas to SEC-compliant financial calculations and peer-reviewed mathematical references.
Who Uses GM Calculator Free Online Calculators
Our 41 free online calculators serve a diverse range of professionals and students who need fast, accurate results without complicated software or sign-up walls.
📊 Digital Marketers
Calculate ROAS for Google Ads and Facebook campaigns, track CPM and CPC costs, measure conversion rates, and optimize customer acquisition costs — all from one dashboard.
💰 Financial Planners
Project compound interest growth, compare loan terms, calculate mortgage affordability with the 28/36 rule, and plan savings goals with inflation-adjusted projections.
💪 Health & Fitness Coaches
Calculate BMR and TDEE with multiple medical formulas, estimate body fat percentage, determine daily water intake needs, and track all health metrics in one dashboard.
🎓 Students & Teachers
Solve percentage problems, compute GPA from letter grades, calculate statistics for research projects, and check homework with fraction, equation, and geometry solvers.
🏢 Small Business Owners
Calculate profit margins and markups, plan marketing budgets by revenue percentage, analyze investment returns, and evaluate customer lifetime value versus acquisition costs.
🚀 Freelancers & Solopreneurs
Calculate tip amounts for client meals, estimate freelance project pricing, track conversion rates from proposals, and plan retirement savings goals with compound interest.
📝 Latest Guides from Our Blog
View all guides →In-depth guides covering marketing, finance, health, and math — from basic formulas to real-world applications.
How to Calculate Percentages: 6 Formulas You'll Use Every Day
Tips, discounts, taxes, growth rates — master the 6 essential percentage formulas with real-world examples for business and everyday life.
Read guide →FinanceCompound Interest: How $500/Month Becomes $1.2M
Real portfolio scenarios, tax-advantaged vs taxable accounts, and the 3 behavioral traps that destroy compounding returns.
Read guide →MarketingROAS vs ROI: The $50,000 Difference Between Looking Profitable and Being Profitable
When to use each metric and why using the wrong one can lead to bad budget decisions that cost thousands.
Read guide →HealthBMR vs TDEE vs RMR: What's the Difference?
Three related but different metabolic metrics — what each measures, when to use which, and how they fit together for weight management.
Read guide →Frequently Asked Questions
Everything you need to know about GM Calculator and our free calculators
What calculators does GM Calculator offer?
GM Calculator offers 41 free online calculators across 4 categories: Marketing (ROAS, break-even ROAS, target ROAS, CPM, CPC, CTR, conversion rate, CAC, LTV:CAC, ROI, marketing budget, CPA, customer retention, churn rate), Finance (simple interest, compound interest, margin & markup, loan, mortgage, savings goal, debt payoff, investment return), Health (BMR, TDEE, body fat, water intake, weight & height, health dashboard), and Math (percentage, fraction, grade & GPA, statistics, percentage increase, ratio, tip, discount, date, equation solver, quadratic solver, pythagorean theorem, scientific notation). All are 100% free with no sign-up required.
Are these calculators really free to use?
Yes, absolutely. All 41 calculators on GM Calculator are completely free to use with no hidden charges, no subscription fees, and no sign-up requirements. Just enter your numbers and get instant results.
How accurate are the calculators?
Our calculators use verified formulas from medical, financial, and mathematical standards. Health calculators use formulas like Mifflin-St Jeor and Harris-Benedict (for BMR), the US Navy method (for body fat), and WHO standards (for BMI). Financial calculators use standard compound interest and margin formulas. All results are precise to 2+ decimal places.
Do I need to create an account to use the calculators?
No account or sign-up is required. Just visit any calculator page, enter your values, and get results instantly. We believe in making tools accessible without barriers.
Can I use these calculators on my phone?
Yes, all calculators on GM Calculator are fully responsive and work on any device — desktop, tablet, and mobile. The interface adapts to your screen size for a seamless experience.
How do I calculate ROAS for my ad campaigns?
Use our ROAS Calculator. Enter your total ad revenue and total ad spend. The tool instantly calculates your ROAS ratio and percentage. You can also use the Break Even ROAS and Target ROAS calculators for more advanced planning.
What is the difference between BMR and TDEE?
BMR (Basal Metabolic Rate) is the calories your body needs at complete rest — about 60-75% of your daily burn. TDEE (Total Daily Energy Expenditure) adds digestion and physical activity on top of BMR. Use our BMR Calculator to understand your metabolism, then use the TDEE Calculator to plan weight changes.
How do I calculate compound interest with inflation adjustment?
Our Compound Interest Calculator shows both nominal growth and inflation-adjusted real returns. Enter your principal, interest rate, time period, and compounding frequency. The tool displays a year-by-year chart and accounts for purchasing power loss due to inflation.