Free Online Calculators & Converters

Quickstart with These Tools

Find the tool you need quickly.

Mathematics

Base Converter

Convert between binary, decimal, hex, and other number bases

Ready to use
Mathematics

Percentage Calculator

Calculate percentages with 5 modes: percentage of number, X is what % of Y, increase/decrease, difference, and reverse percentage

Ready to use
Mathematics

Quadratic Equation Solver

Solve quadratic equations ax² + bx + c = 0 with step-by-step solutions, discriminant analysis, and visual parabola graph

Ready to use
Finance

Mortgage Calculator

Calculate monthly payments and amortization schedules

Ready to use
Finance

Compound Interest

Calculate investment growth with compound interest

Ready to use
Finance

Loan Prepayment Calculator

See how extra payments save money and time on loans

Ready to use
Finance

Prepayment vs Refinance Calculator

Compare prepayment vs refinancing strategies

Ready to use
Finance

Car Buy vs Lease Calculator

Compare monthly payments, total costs, break-even points, and get recommendations based on your driving habits

Ready to use
Finance

Solar Panel ROI Calculator

Calculate solar panel costs, savings, and ROI. Get payback period, 25-year projections, and environmental impact estimates

Ready to use
Science

Physics Unit Converter

Convert force, energy, speed, and power units

Ready to use
Graphics

Color Converter

Convert RGB, Hex, HSL and generate color palettes

Ready to use
Text Tools

ASCII Table

View ASCII character codes in multiple formats

Ready to use
Education

Grade Calculator

Calculate weighted grade averages

Ready to use
Education

GPA Calculator

Calculate GPA with plus/minus grades

Ready to use
Education

Final Grade Calculator

Find the grade needed on your final exam

Ready to use
Education

Turtle Graphics

Learn programming by drawing with turtle graphics commands

Ready to use
Health

BMI Calculator

Calculate Body Mass Index and healthy weight range

Ready to use
Health

Glucose to A1C Converter

Convert between blood glucose and HbA1c values

Ready to use
Health

Kids Growth Calculator

Calculate child height/weight percentiles (WHO standards)

Ready to use
Health

Penile Percentile Calculator

Calculate percentiles based on medical research data

Ready to use
Time

Age Calculator

Calculate your exact age and days until next birthday

Ready to use
Productivity

JSON Validator

Validate, format, and minify JSON with error detection

Ready to use
Productivity

Password Generator

Generate strong, secure passwords with customizable options

Ready to use
Productivity

Base64 Encoder/Decoder

Encode and decode Base64 strings with file support

Ready to use
Productivity

Markdown Editor

Professional markdown editor with live preview and document management

Ready to use
Productivity

Mermaid Diagram Editor

Advanced Mermaid diagram editor with beautiful themes, real-time preview, and export options

Ready to use
Tech Tools

API Rate Limit Calculator

Calculate optimal rate limits for APIs. Supports multiple strategies and generates Nginx, Kong, AWS configurations

Ready to use
Tech Tools

System Latency Budget Calculator

Allocate latency budgets across frontend, backend, network, database layers. Track P95 performance targets and identify bottlenecks

Ready to use
Tech Tools

Kafka Message Size Calculator

Calculate Kafka message size including overhead, batch size, compression, and throughput estimation

Ready to use
Tech Tools

Jira Story Points Calculator

Calculate agile story points using Fibonacci sequence. Input complexity, effort, and risk factors to get recommended point values

Ready to use
Tech Tools

LLM Token Budget Calculator

Calculate LLM API costs for 50+ models. Estimate token usage, daily/monthly costs, and find cheaper alternatives

Ready to use
Tech Tools

LLM Self-Hosted vs API Calculator

Calculate when self-hosting an LLM pays off vs using cloud APIs. Compare costs for GPT-4, Claude, Llama, and more

Ready to use
Tech Tools

DORA Metrics Calculator

Measure DevOps performance with the four DORA metrics: deployment frequency, lead time, change failure rate, and time to restore

Ready to use