Number Converters — Free Online Tools
Convert numbers between any base or format with our free online number converters. Each tool runs entirely in your browser — nothing is uploaded to any server. Perfect for developers, students, and IT professionals who need quick, private conversions.
Popular Number Conversions
Unit Converter
Convert between 100+ units across length, mass, volume, temperature, area, speed, and more. All-in-one measurement tool.
Percentage Calculator
Calculate percentages, percentage changes, and ratios. Perfect for discounts, tax, tips, and statistical analysis.
Base64 Encoder/Decoder
Encode text to Base64 or decode Base64 back to text. Essential for data URLs, JWT tokens, and API payloads.
Slug Generator
Generate clean, SEO-friendly URL slugs from any text. Used by bloggers, content teams, and web developers daily.
Date & Time Number Conversions
Age Calculator
Calculate exact age in years, months, and days. Shows time until your next birthday with precise countdown.
Date Difference Calculator
Calculate the exact number of days, months, and years between any two dates. Great for project planning and deadlines.
Time Zone Overlap
Find overlapping business hours across time zones. Essential for remote teams scheduling meetings across continents.
Sleep Cycle Calculator
Calculate ideal bedtimes based on 90-minute sleep cycles. Wake up refreshed by timing your alarm to the right cycle.
Financial Number Calculators
Profit Margin Calculator
Calculate profit margin, markup percentage, and selling price. Business tool for pricing products and services effectively.
Discount Calculator
Calculate final price after percentage or fixed discounts. See exactly how much you save on any purchase.
Break-Even Calculator
Find your break-even point based on fixed costs, variable costs, and unit price. Essential for startup financial planning.
Marketplace Fee Calculator
Calculate seller fees for Amazon, eBay, Etsy, Mercari, Poshmark, and more. Know your net profit on every sale.
Unit-Converters
Celsius to Fahrenheit
Convert temperatures from Celsius to Fahrenheit instantly. Free temperature converter with formula reference.
Fahrenheit to Celsius
Convert Fahrenheit to Celsius with our free temperature converter. Quick and accurate for weather, cooking, and science.
Feet to Meters
Convert feet to meters and meters to feet. Essential for construction, travel, and international measurement conversions.
Gallons to Liters
Convert gallons to liters and vice versa. Perfect for fuel economy, cooking recipes, and liquid measurements.
Inches to CM
Convert inches to centimeters instantly. Ideal for screen sizes, clothing measurements, and DIY projects.
KG to LBS
Convert kilograms to pounds and pounds to kilograms. Fitness, shipping, and everyday weight conversion tool.
Miles to KM
Convert miles to kilometers and kilometers to miles. Essential for travel planning and distance calculations.
Why Use Our Number Converters?
- 100% private — All calculations happen in your browser. Nothing is sent to any server.
- No signup or download — Open the tool and start converting immediately. No accounts, no apps.
- Free forever — Every converter is completely free with no usage limits, no ads in tool results.
- Works offline — Once loaded, many tools can be used without an internet connection (PWA).
- Mobile-friendly — All tools work on phones, tablets, and desktops with responsive layouts.