Converters, Calculators & Quick Answers
Apex Conversion is a free, no-sign-up collection of unit converters, everyday calculators, and reference guides — convert a measurement, size up a home project, work out a loan payment, or settle a quick calculation, all in one place.
Popular Categories
Pick a category below to start converting. All tools are free and require no sign-up.
Length
Meters, feet, inches, miles, kilometers, and more.
Weight
Pounds, kilograms, ounces, grams, and tonnes.
Temperature
Celsius, Fahrenheit, Kelvin — switch between all three.
Volume
Liters, gallons, cups, fluid ounces, and milliliters.
Area
Square feet, acres, hectares, square meters, and more.
Speed
Miles per hour, km/h, knots, meters per second.
Popular Conversions
Jump straight to the most commonly needed unit conversions.
Popular Calculators
Free everyday calculators for finance, health, and time — all run in your browser.
Retirement Calculator
Project your retirement balance from savings, contributions, and return rate.
🏠Mortgage Calculator
Find your monthly payment from home price, down payment, rate, and term.
📈Compound Interest
Calculate investment growth with custom compounding frequency.
⚖️BMI Calculator
Calculate Body Mass Index in metric or imperial units.
🎂Age Calculator
Find exact age in years, months, and days from a date of birth.
🌍Time Zone Converter
Convert time between ET, CT, MT, PT, UTC, London, Paris, Tokyo, and more.
Popular Resources
Curated reference tables and printables you can bookmark and return to — measurements, time, finance, and more.
Guides Hub
Measurement, engineering, finance, cooking, and data guides — all in one place.
📐Measurement Reference Library
Metric prefixes, paper sizes, wire gauge, drill bits, thread sizes.
💵Finance Reference Library
Tax brackets, 401(k) limits, IRA limits, HSA limits, inflation history.
🖨️Printable Resources
Print-ready conversion charts, metric chart, kitchen conversions.
Popular Guides
In-depth reference guides covering measurement systems, conversion formulas, engineering units, finance math, and more.
Conversion Formulas Handbook
Every formula you need — length, weight, temperature, area, volume, pressure, and more.
🌐Measurement Systems Handbook
SI, metric, imperial, and US customary — where each is used and how they differ.
⚙️Engineering Units Handbook
Pressure, force, energy, power, torque — the full SI vs. imperial reference.
💰Finance Calculator Guide
Compound interest, mortgages, retirement, and loan calculators explained.
📊Finance Formula Handbook
Compound interest, APR vs. APY, future value, rule of 72, and more.
🔢Metric Prefixes Guide
Kilo, mega, giga, nano — every SI prefix with values and real-world examples.
📖Unit Conversion Dictionary
Definitions for every common unit across length, weight, temperature, pressure, and data.
🔵Pressure Units Explained
PSI, kPa, bar, atm, mmHg — how each pressure unit works and when to use it.
All conversion results on Apex Conversion are provided for general informational purposes only. While we strive for accuracy, results should not be used for professional, medical, legal, or engineering decisions without independent verification. Read our full disclaimer.