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Explore in-depth articles about measurement systems and practical conversion guides.
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Step-by-step guides for converting temperature, length, weight, volume, and more with practical examples.
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Unit Conversion for Students: A Reliable Method
Most conversion mistakes are method mistakes: multiplying when you should divide, forgetting to square a factor, or keeping too many digits. This guide teaches one method — dimensional analysis — that works for any conversion, with worked examples for length, mass, volume, speed and compound units. It does not explain the measurement systems themselves; those have their own guides, linked below.
Metric vs Imperial vs US Customary: How the Systems Differ
"Metric vs Imperial" usually hides three systems: the metric system (today the SI), the British Imperial system, and US customary units. Imperial and US customary share many unit names and some identical definitions, but not all — and the differences are where conversions go wrong. This guide compares the systems quantity by quantity. How the SI itself is structured is covered in the SI units guide.
SI Units Explained: Base Units, Derived Units and Prefixes
The International System of Units (SI) is the modern form of the metric system, maintained by the International Bureau of Weights and Measures (BIPM). It is not a list of unrelated units: seven base units are combined into derived units, prefixes scale any unit by powers of ten, and a short set of writing rules keeps values unambiguous. This guide explains that structure. How SI compares with Imperial and US units is covered separately.
How to Calculate Heat Pump Savings and Payback
Whether a heat pump costs less to run than your current heating, and how long the extra installation cost takes to recover, depends on your own numbers: how much heat the home needs, the efficiency of your current system, the heat pump's seasonal efficiency in your home, and your fuel and electricity prices. Not every household will save money. This guide shows how to compare the cost of useful heat, runs several illustrative scenarios — including one where the heat pump costs more — and explains why payback is so sensitive to assumptions. What COP and SCOP mean is covered in the COP and SCOP guide.
Heat Pump Efficiency Guide: Understanding COP and SCOP
A heat pump's efficiency is not one fixed number. COP describes performance at one set of test conditions; SCOP describes a whole heating season under a reference climate. Both change with the outdoor temperature, the water temperature the heating system needs, defrosting and how the system is controlled. This guide explains what each figure means, how ratings are produced, why a catalogue figure is not necessarily what your home will achieve, and how to turn a seasonal figure into electricity use. Running-cost and payback comparisons are covered in the heat pump savings guide.
How to Build a Plan to Cut Your Carbon Footprint by 50%
A 50% cut is a target to test, not a result anyone can promise. Whether it is realistic depends on what your footprint is made of: a household that heats with gas, drives a lot and flies often has very different options from one that already does none of those. This guide is a planning method — measure a baseline, find the largest categories, model changes in tonnes, then recalculate the same way to track progress. How to build the baseline itself is covered in the carbon footprint guide.