Unit Converter - Convert Length, Weight, Temperature, Volume Free

How This Tool Works

Our unit converter uses a base unit approach for each conversion category. When you enter a value in any unit, the calculator first converts it to the base unit (meters for length, kilograms for weight, Celsius for temperature), then converts from the base unit to your target unit. For example, converting feet to yards goes: feet → meters (multiply by 0.3048) → yards (divide by 0.9144). This two-step process ensures accuracy and consistency across all unit combinations.

Temperature conversions use specialized formulas rather than simple multiplication because temperature scales have different zero points and intervals. The calculator converts Fahrenheit to Celsius using (°F - 32) × 5/9, Celsius to Fahrenheit using (°C × 9/5) + 32, and handles Kelvin by adding or subtracting 273.15 from Celsius. These formulas are hard-coded to ensure precision for this unique conversion type.

All conversions use internationally recognized conversion factors (like 1 inch = exactly 2.54 cm, 1 pound = exactly 453.592 grams) defined by standards organizations like NIST. The calculator maintains high precision internally—typically 15 significant digits—and intelligently formats results based on magnitude, showing more decimals for small numbers and fewer for large ones. Everything processes instantly in your browser with zero data transmission.

Why Use This Tool

Unlike memorizing conversion factors or juggling multiple single-purpose calculators, our universal unit converter handles eight conversion categories with dozens of units, providing instant bidirectional conversion with reference tables and common conversion examples for educational value.

• Eight conversion types: Length, weight, temperature, volume, area, speed, time, and digital storage—virtually every common measurement need in one tool
• Bidirectional conversion: Convert in either direction with one click of the swap button—no need to remember which formula to use
• Smart formatting: Automatically adjusts decimal precision based on result magnitude, preventing unnecessary zeros or scientific notation for readability
• Educational value: Built-in reference table shows common conversions for each category, helping you learn while you calculate
• International support: Includes both metric (used by 95% of the world) and imperial (US/UK) units, plus specialized units like knots for maritime use

Compared to Google searches that provide only single conversions, conversion apps requiring installation, or printed conversion tables limited to common units, our tool offers comprehensive coverage, instant results, offline capability after loading, and complete privacy—all without ads or tracking.

How to Use the Unit Converter

Unit conversion is the process of changing a measurement from one unit to another while maintaining the same quantity. Whether you're traveling internationally, following recipes, working on projects, or studying science, unit conversion is an essential skill for everyday life.

Length / Distance Conversions

Length measures distance between two points:

• Metric Units: Millimeter (mm), Centimeter (cm), Meter (m), Kilometer (km)
• Imperial Units: Inch (in), Foot (ft), Yard (yd), Mile (mi)
• Common Conversions: 1 inch = 2.54 cm, 1 foot = 30.48 cm, 1 meter = 3.281 feet, 1 mile = 1.609 km
• Real-World Use: Height measurements, distance travel, construction, screen sizes
• Memory Tip: A meter is roughly one big step, a kilometer is about 5/8 of a mile

Weight / Mass Conversions

Weight and mass measure the amount of matter in an object:

• Metric Units: Milligram (mg), Gram (g), Kilogram (kg), Metric Ton (t)
• Imperial Units: Ounce (oz), Pound (lb), Stone (st), Ton
• Common Conversions: 1 kg = 2.205 lbs, 1 pound = 453.6 grams, 1 ounce = 28.35 grams
• Real-World Use: Body weight, food portions, shipping packages, ingredient measurements
• Memory Tip: A kilogram is about 2.2 pounds, so multiply kg by 2 for a rough estimate

Temperature Conversions

Temperature measures heat intensity using different scales:

• Celsius (°C): Water freezes at 0°C, boils at 100°C. Used worldwide except US
• Fahrenheit (°F): Water freezes at 32°F, boils at 212°F. Used primarily in US
• Kelvin (K): Absolute zero at 0 K, water freezes at 273.15 K. Used in science
• Conversion Formulas: °F = (°C × 9/5) + 32, °C = (°F - 32) × 5/9, K = °C + 273.15
• Quick Reference: 0°C = 32°F (freezing), 20°C = 68°F (room temp), 37°C = 98.6°F (body temp)
• Memory Tip: To estimate F to C, subtract 30 and divide by 2 (rough but useful)

Volume Conversions

Volume measures the amount of space a substance occupies:

• Metric Units: Milliliter (mL), Liter (L), Cubic Meter (m³)
• Imperial Units: Fluid Ounce (fl oz), Cup, Pint (pt), Quart (qt), Gallon (gal)
• Common Conversions: 1 liter = 33.814 fl oz, 1 gallon = 3.785 liters, 1 cup = 237 mL
• Real-World Use: Cooking recipes, fuel efficiency, beverage serving sizes, aquariums
• Important Note: UK and US gallons differ (UK gallon = 1.2 US gallons)

Area Conversions

Area measures the size of a two-dimensional surface:

• Metric Units: Square Millimeter (mm²), Square Centimeter (cm²), Square Meter (m²), Hectare (ha), Square Kilometer (km²)
• Imperial Units: Square Inch (in²), Square Foot (ft²), Square Yard (yd²), Acre, Square Mile (mi²)
• Common Conversions: 1 m² = 10.764 ft², 1 acre = 4,047 m², 1 hectare = 2.471 acres
• Real-World Use: Real estate, land surveying, farming, room sizes, flooring
• Memory Tip: An acre is roughly the size of a football field without end zones

Speed Conversions

Speed measures distance traveled per unit of time:

• Common Units: Meters per second (m/s), Kilometers per hour (km/h), Miles per hour (mph), Knots
• Conversions: 1 mph = 1.609 km/h, 1 m/s = 3.6 km/h, 1 knot = 1.852 km/h
• Real-World Use: Vehicle speeds, wind speed, running pace, internet bandwidth
• Quick Reference: 100 km/h ≈ 62 mph (highway), 10 m/s ≈ 36 km/h ≈ 22 mph
• Scientific Context: Speed of light = 299,792,458 m/s (constant in physics)

Time Conversions

Time measures duration between events:

• Units: Millisecond (ms), Second (s), Minute (min), Hour (hr), Day, Week, Month, Year
• Standard Conversions: 60 seconds = 1 minute, 60 minutes = 1 hour, 24 hours = 1 day, 7 days = 1 week
• Complex Conversions: 365.25 days = 1 year (accounting for leap years), 52.18 weeks = 1 year
• Real-World Use: Scheduling, project management, cooking times, travel duration
• Decimal Time: Some systems use decimal hours (1.5 hours = 1 hour 30 minutes)

Digital Storage Conversions

Digital storage measures data capacity:

• Binary Units: Byte (B), Kilobyte (KB), Megabyte (MB), Gigabyte (GB), Terabyte (TB), Petabyte (PB)
• Conversion Factor: Each step is ×1024 (2^10) in binary, or ×1000 in decimal (SI standard)
• Common Sizes: 1 KB ≈ 1,024 bytes, 1 MB ≈ 1,024 KB, 1 GB ≈ 1,024 MB, 1 TB ≈ 1,024 GB
• Real-World Use: Hard drive capacity, RAM, file sizes, internet data plans
• Important Note: Storage manufacturers often use 1000-based (decimal) while operating systems use 1024-based (binary)
• Bits vs Bytes: 8 bits = 1 byte. Internet speeds often measured in bits (Mbps), storage in bytes (MB)

Metric System Prefixes

Understanding metric prefixes makes conversion easier:

• Kilo- (k): ×1,000 (kilometer = 1,000 meters)
• Hecto- (h): ×100 (hectare = 100 ares)
• Deca- (da): ×10 (decameter = 10 meters)
• Base Unit: Meter, Gram, Liter (no prefix)
• Deci- (d): ÷10 (decimeter = 0.1 meter)
• Centi- (c): ÷100 (centimeter = 0.01 meter)
• Milli- (m): ÷1,000 (millimeter = 0.001 meter)
• Micro- (μ): ÷1,000,000 (micrometer = 0.000001 meter)

Conversion Best Practices

Follow these tips for accurate conversions:

• Use Exact Factors: Use precise conversion factors, not rounded estimates, for accuracy
• Keep Extra Decimals: Maintain more decimal places during calculation, round only the final answer
• Unit Cancellation: Write units in fractions to ensure they cancel correctly in multi-step conversions
• Double-Check Direction: Make sure you're multiplying or dividing in the right direction
• Verify Reasonability: Check if the result makes sense (1 km shouldn't convert to 10 feet)
• Context Matters: Consider if you need scientific precision or practical approximation

Common Conversion Mistakes

Avoid these frequent errors:

• Squared/Cubed Units: Area and volume conversions require squaring/cubing the conversion factor (1 m² = 10.764 ft², not 3.281 ft²)
• Temperature Formula Errors: Temperature conversion formulas are different from simple multiplication
• Confusing Similar Units: Fluid ounces (volume) vs ounces (weight), UK vs US gallons
• Mixing Unit Systems: Don't mix metric and imperial in the same calculation without converting
• Ignoring Context: Recipe conversions may need adjustment beyond pure mathematical conversion
• Rounding Too Early: Each rounding step introduces error; wait until the final result

International Standards

Understanding global measurement systems:

• SI System: International System of Units, used by most of the world for science and commerce
• Metric Countries: All countries officially use metric except USA, Liberia, and Myanmar
• US System: USA primarily uses imperial/customary units (feet, pounds, Fahrenheit)
• UK System: UK uses mixed system (metric for most, imperial for road distances and beer)
• Aviation/Maritime: International standards use nautical miles, knots, and feet for altitude
• Scientific Community: Universally uses metric/SI units for consistency and precision

Limitations & Things to Know

For accurate and reliable unit conversions, be aware of these important points:

• Precision vs accuracy: While calculations use high-precision arithmetic (15 significant digits), results are only as accurate as the input. Measured values have inherent uncertainty—converting 1.5 feet (measured with a ruler) to centimeters doesn't make it more precise than the original measurement.
• UK vs US units differ: US and UK gallons are different (1 UK gallon = 1.2 US gallons). Similarly, US and UK tons differ. This calculator uses US customary units unless specifically noted. Always verify which standard your source uses.
• Temperature scale differences: Temperature conversions aren't simple multiplication because scales have different zero points. 0°C ≠ 0°F ≠ 0K. Only temperature differences (not absolute temperatures) can be multiplied by simple ratios.
• Area and volume conversions: When converting area, the conversion factor must be squared (1 m = 3.281 ft, so 1 m² = 10.764 ft²). For volume, cube it. This calculator handles this automatically, but be aware when doing manual calculations.
• Digital storage binary vs decimal: Storage manufacturers use 1000-based units (1 KB = 1000 bytes), but operating systems use 1024-based (1 KiB = 1024 bytes). This calculator uses the 1024-based (binary) standard. This is why a "500 GB" hard drive shows as ~465 GB in Windows.
• Time conversions with months/years: Months and years have variable lengths (28-31 days per month, 365-366 days per year). This calculator uses averages: 30 days/month, 365 days/year. For precise date calculations, use a date calculator instead.
• Not for currency: Currency conversion requires current exchange rates that change constantly. This tool converts physical units with fixed relationships, not currencies with variable rates.
• Significant figures: The calculator displays many decimal places for precision, but in practical use, round to match your measurement's precision. Converting 2 feet (1 significant figure) to 60.96 cm suggests false precision—61 cm is more appropriate.