Free Online Calculators
Browse CalcFuel's full library of free calculators — social media metrics, marketing ROI, fuel and travel costs, finance, and developer tools. Every page explains the formula and includes practical examples.
Not sure where to start? Try the Social Media Character Counter, ROAS Calculator, or Follower Growth Rate Calculator.
Social Media Calculators
Engagement rate, follower growth, ROI, character counting, and post length tools for Instagram, LinkedIn, TikTok, and X.
- › Character Counter
- › Engagement Rate
- › Follower Growth
- › Social ROI
Marketing & Email Calculators
Open rate, CTR, list growth, ROAS, CAC, and campaign ROI calculators for marketers worldwide.
- › Email Open Rate
- › ROAS
- › Marketing ROI
- › Click-Through Rate
Financial & ROI Calculators
Marketing ROI, profit margins, break-even, mortgages, loans, and compound interest — plus Australia-specific tax tools.
- › Marketing ROI
- › Profit Margin
- › Mortgage Repayment
- › Income Tax (AU)
Conversion & Revenue Calculators
Conversion rate, CAC, CLV, CPL, churn, and revenue-per-lead tools to measure funnel performance.
- › Conversion Rate
- › Customer Acquisition Cost
- › Customer Lifetime Value
- › Churn Rate
Fuel & Energy Calculators
Trip fuel costs, commute budgets, EV vs petrol comparisons, boat fuel, and fleet surcharge tools.
- › Trip Fuel Cost
- › Commute Fuel Cost
- › EV vs Petrol
- › Drive vs Fly
SEO & Web Tools
Website speed impact, traffic projections, NPS, and marketing health assessments.
- › Website Speed Impact
- › Website Traffic
- › Net Promoter Score
- › Marketing Health Check
AI Developer Tools
Model routing savings, prompt caching discounts, multimodal payload costs, and RAG storage estimators.
- › Model Router Savings
- › Prompt Caching
- › Multimodal Payload
- › RAG Storage Cost
Don't see what you need?
Suggest a calculator or upvote community ideas — we build what people ask for most.
Suggest a calculatorHow to Choose the Right Calculator
CalcFuel groups tools by the decision you are trying to make. If you are optimising social content, start in the Social Media hub. If you are planning ad spend or measuring campaign returns, use Marketing & Email or Financial calculators. For trip planning or fleet costs, browse Fuel & Energy.
Some calculators are region-specific — for example Australian income tax, HECS-HELP, and stamp duty — and are clearly labeled. Global tools like ROAS, engagement rate, and fuel cost estimators work anywhere.
Popular Tools
- Social Media Character Counter — live counts for X, LinkedIn, Instagram, and Facebook
- Follower Growth Rate Calculator — track audience growth month over month
- ROAS Calculator — measure return on ad spend
- Boat Fuel Calculator — estimate marine fuel costs
- Australian Income Tax Calculator — FY2025–26 estimates (Australia only)