Convert between hundreds of units across engineering, science, and everyday measurements — all on one dashboard. No page hopping.
⏱ 3 min read📐 30 categories · 200+ units🇬🇧 UK-focused
Most unit conversion needs one simple lookup — but if you work across disciplines,
or you're an engineer, scientist, or student, you'll often need to switch between
everyday units and specialist engineering measurements
in the same sitting. Jumping between ten different converter pages wastes time and breaks flow.
This dashboard splits its 30 categories into two tiers: Basic Units
(length, mass, temperature, volume, area, speed, time, and more) for day-to-day
conversions, and Engineering & Science for specialist work —
dynamic viscosity, kinematic viscosity, thermal conductivity, heat transfer coefficient,
volumetric flow rate, and others you won't easily find on a general-purpose converter.
Throughout, you'll find UK-specific units treated as first-class options:
the UK gallon (4.546 L vs the US gallon's 3.785 L), UK MPG, stone, UK long ton, and
UK fluid ounces all appear where relevant.
All conversions happen entirely in your browser — no data is sent
to any server.
Unit Converter Tool
Further Reading
Engineering Units — Why They Matter
Engineers encounter unit conversion constantly: a fluid dynamics calculation might
require dynamic viscosity in Pa·s but a vendor datasheet quotes centipoise (cP);
a heat exchanger design uses W/(m·K) for thermal conductivity while an older
British Standard reference gives BTU/(hr·ft·°F). Getting the conversion right is
not just a convenience — a factor-of-ten error in viscosity changes a Reynolds
number, changes the flow regime, and can invalidate an entire design.
The Engineering & Science section of this tool covers the units most likely to
cause trouble: viscosity (both dynamic and kinematic), thermal conductivity,
heat transfer coefficients, specific heat capacity, mass flow rate, and volumetric
flow rate. Each category includes SI base units, common CGS equivalents, and the
Imperial units still found in US engineering codes and UK legacy documentation.
UK vs US vs SI Units
The most dangerous unit trap for UK engineers working with American colleagues is
the gallon. 1 UK gallon = 4.546 litres; 1 US gallon = 3.785 litres
— a 20% difference. This cascades into fuel efficiency: a car doing 40 MPG on a
UK road test is doing roughly 33 MPG by US measurement standards, and about
7.1 L/100km by the European standard. All three measures describe the same car.
Similarly, the UK ton (long ton) is 2,240 lb = 1,016 kg, while
the US short ton is 2,000 lb = 907 kg, and the metric tonne is 1,000 kg exactly.
In international shipping and commodity trading, all three appear. SI units are
always unambiguous and should be preferred for engineering calculations — the
conversions here help you move between whatever standard a document uses and
the SI values you need.
Frequently Asked Questions
What's the difference between dynamic and kinematic viscosity?+
Dynamic (absolute) viscosity (Pa·s, cP) measures a fluid's internal resistance to shear — how thick or sticky it is. Kinematic viscosity (m²/s, cSt) is dynamic viscosity divided by density (ν = μ/ρ). Water at 20°C has μ ≈ 1 cP and ν ≈ 1 cSt. Use dynamic viscosity for force and pressure-drop calculations; kinematic viscosity for pipe flow, lubrication, and gravity-driven fluid problems.
How do I convert UK MPG to L/100km?+
Use: L/100km = 282.481 ÷ MPG(UK). For example, 40 MPG UK = 7.06 L/100km. The constant 282.481 comes from the UK gallon (4.54609 L) and the mile–kilometre conversion (1.60934). UK and US MPG differ because the gallons are different sizes — always specify which MPG you mean when communicating fuel economy across regions.
What is a Rankine (°R) and when is it used?+
Rankine is an absolute temperature scale used mainly in US engineering (aerospace, thermodynamics, legacy HVAC). It uses Fahrenheit-sized degrees but starts at absolute zero (0°R = −459.67°F). Water freezes at 491.67°R, boils at 671.67°R. Convert: °R = °F + 459.67. It is the US equivalent of Kelvin — both are absolute scales, just using different degree sizes.
How accurate are the conversions on this tool?+
All conversions use internationally recognised, NIST-recommended conversion factors, accurate to IEEE 754 double-precision floating point (≈15–17 significant digits). Results display to up to 8 significant figures. Key exact values: 1 inch = 0.0254 m exactly; 1 lb = 0.45359237 kg exactly; temperature formulas are algebraically exact. No data is sent anywhere — all arithmetic runs locally in your browser.
Can I use this on mobile?+
Yes — the converter is fully responsive. On mobile and tablet, the category sidebar collapses to a dropdown selector above the conversion panel. All 30 categories and 200+ units are available on every screen size. The tool works in any modern mobile browser with no app required. Your last-used units per category are saved locally so they persist between visits.
Disclaimer: Conversion factors are based on internationally recognised standards (NIST, ISO, BIPM).
Results are provided for informational and educational purposes. For safety-critical or legal applications,
always verify conversions against primary reference standards. This tool performs all calculations locally
in your browser — no data is transmitted or stored externally.