Free calculators that answer real questions
Should you refinance? Is your ad profitable? Enter your numbers — get the answer in seconds, with the work shown.
Real questions, answered with real numbers:
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.
Quick Calculator
What’s 15% of 200? Try it live →
15% of 200
30
(15 ÷ 100) × 200
Made for real questions like these
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.
100% Private
Your numbers never leave your device. No sign-up, no account — your calculations stay in your browser.
Works Everywhere
Desktop, tablet, phone — same great experience. Built with modern responsive design.
What You Can Calculate with GM Calculator
GM Calculator gives you 42 free online calculators across four essential categories — marketing, finance, health, and math. Every tool is designed for instant results with no sign-up, no account required, 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 42 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.
Most Popular Calculators
The tools our users rely on most
Return on Ad Spend Calculator
Calculate ROAS to measure the effectiveness of your advertising campaigns.
Compound Interest Calculator
Calculate compound interest with inflation-adjusted returns. See how your money grows exponentially over time.
Percentage Calculator
Calculate percentages, percentage increases, and percentage changes.
TDEE Calculator
Calculate Total Daily Energy Expenditure for weight management.
Body Fat Calculator
Calculate body fat percentage using the US Navy method.
Margin & Markup Calculator
Calculate profit margin, markup percentage, and selling price from cost and revenue.
Browse by Category
Find the right calculator for your needs
Marketing
Free marketing calculators for ROAS, CPC, CPM and more.
Finance
Free finance calculators for mortgages, loans, compound interest and more.
Health
Free health calculators for BMR, TDEE, body fat and more.
Math
Free math calculators for percentages, fractions, statistics and more.
Who Uses GM Calculator Free Online Calculators
Our 42 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.
Last updated: September 27, 2026