Unit Conversion Guides
Detailed explanations of unit systems, conversion principles, and common points of confusion. Useful background for engineers, students, and anyone who needs to work across unit systems.
SI vs Imperial Units: A Complete Guide
Understand the difference between SI (metric) and imperial units. History, key differences, which countries use which system, and the conversions that matter most in daily practice.
Updated May 2026
US Gallon vs Imperial Gallon: What's the Difference?
The US gallon (3.785 L) and the UK imperial gallon (4.546 L) are different units sharing one name. This guide explains the 20% volume gap, where each is used, and how to convert between them.
Updated May 2026
Mass vs Force: Understanding the Difference
Mass measures the amount of matter in an object; force is the gravitational pull on that mass. The distinction matters in physics and engineering — here is when the difference shows up and how to handle it.
Updated May 2026
Temperature Conversion Explained: Celsius, Fahrenheit, and Kelvin
Why temperature conversions need both a multiplier and an offset, where each scale is used, and how to convert quickly without errors. Covers Celsius, Fahrenheit, Kelvin, and Rankine.
Updated May 2026
Common Pressure Units: PSI, Bar, kPa, atm, and mmHg Explained
Pressure measurement spans more units than almost any other physical category. This guide explains psi, bar, kPa, atm, mmHg, and pascal — where each is used and how to convert.
Updated May 2026
Torque Units Explained: Newton-Metres vs Pound-Feet vs Pound-Inches
Torque measures rotational force and is specified in different units across automotive, industrial, and aerospace work. This guide explains N·m, lb·ft, and lb·in and how to convert without errors.
Updated May 2026
Binary vs Decimal Data Units: Bytes, Kibibytes, and Why 1 GB ≠ 1 GiB
A "1 TB" hard drive shows as 931 GB on your computer because two unit conventions compete for the same prefix. This guide explains decimal SI vs binary IEC and how to read storage figures correctly.
Updated May 2026
Tonne vs Ton: Metric Ton, Short Ton, and Long Ton Explained
Three different units share the name "ton" with different volumes: the metric tonne (1000 kg), the US short ton (907 kg), and the UK long ton (1016 kg). This guide explains the differences and where each is used.
Updated May 2026
Degrees vs Radians: When to Use Each and Why
Degrees and radians are two ways to measure angles. This guide explains the difference, when each is used, and why mathematics and physics prefer radians while everyday work uses degrees.
Updated May 2026
Internet Speeds Explained: Mbps, MB/s, and What Your Plan Actually Delivers
A "1 Gbps" internet plan delivers about 940 Mbps in real-world testing, and a 1 GB file takes 80 seconds to download — not 8 seconds. This guide explains why bits and bytes differ and how to read internet speed figures.
Updated May 2026
Energy Units Explained: Joules, kWh, BTU, and Calories
Energy is measured in joules in scientific work, kilowatt-hours on electricity bills, BTU in HVAC, and calories in food. This guide explains what each unit means and how to convert between them.
Updated May 2026
Speed Units Explained: mph, km/h, m/s, and Knots
Speed is measured in different units depending on context: mph in US road travel, km/h in metric road travel, m/s in scientific work, and knots in aviation and maritime navigation. This guide explains each.
Updated May 2026
How we verify content
All conversion factors are sourced from NIST, SI, and ISO publications. Read our full methodology →