QuickMergeMetric to Standard Conversion Calculator and Charts
Short answer: To convert between units, enter a value, choose the source and target units, then copy the converted result. QuickMerge calculates the conversion locally in your browser.
Convert metric to standard units and back — length, weight, temperature, volume and area — with the calculator above, or read the value straight off the reference charts below. Everything is computed in your browser, so nothing you enter is sent to a server.
How do I convert between units of measurement?
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Convert Between Units Without the Mental Maths
Measurement gets confusing the moment two systems collide. A recipe lists grams while your scale reads ounces; a hiking trail is marked in kilometres but your map app thinks in miles; an overseas oven dial shows Celsius when you grew up on Fahrenheit. This converter exists to take that friction away. Pick a category, type a number, choose the unit you have and the unit you want, and the answer updates the instant you change anything. There is no Convert-and-wait step, no pop-up, and nothing leaves your device. The seven categories on this page cover the conversions people actually reach for day to day rather than an exhaustive scientific table you would have to scroll through to find the one you need.
The Seven Categories on This Page
Each category has its own set of units, and switching categories instantly repopulates the two dropdowns:
- Length: metres, kilometres, centimetres, millimetres, miles, yards, feet and inches. Useful for everything from a person's height to road distances and the dimensions of a parcel.
- Weight: kilograms, grams, milligrams, pounds, ounces, stones and metric tons. Covers cooking, postage, body weight and shipping.
- Temperature: Celsius, Fahrenheit and Kelvin. The everyday pair is Celsius and Fahrenheit; Kelvin is there for science and engineering work.
- Volume: litres, millilitres, US gallons, UK (imperial) gallons, cubic metres, cubic feet and cubic inches. Note that a US gallon and a UK gallon are not the same size, which is exactly why both are listed separately.
- Digital Storage: bytes, kilobytes, megabytes, gigabytes, terabytes and petabytes. These steps use the binary 1024-based definition, so one kilobyte here is 1024 bytes rather than 1000.
- Area: square metres, square kilometres, square centimetres, square miles, square yards, square feet, acres and hectares. Handy for room sizes, land plots, and property listings.
- Speed: metres per second, kilometres per hour, miles per hour, knots and feet per second. Useful for vehicle speeds, wind and weather reports, and nautical or aviation figures.
Everyday Conversions People Search For
Most conversions come down to a handful of well-worn pairs. Here are the common ones and roughly what to expect, so you can sanity-check a result at a glance:
- Centimetres to inches: divide by 2.54. So 30 cm is about 11.8 inches, and a 15 cm phone is just under 6 inches.
- Kilograms to pounds: multiply by about 2.205. A 70 kg person weighs roughly 154 pounds, and a 5 kg parcel is about 11 pounds.
- Celsius to Fahrenheit: multiply by 9, divide by 5, then add 32. Body temperature of 37°C is 98.6°F, and a warm 25°C day is 77°F.
- Kilometres to miles: multiply by about 0.621. A 10 km run is roughly 6.2 miles, and 100 km/h is close to 62 mph.
- Millilitres to fluid ounces: a US fluid ounce is about 29.6 ml, so a 500 ml bottle holds close to 17 US fl oz.
The quick-conversion buttons above the converter load several of these popular pairs in a single click, and the swap button flips the two units so you can read the conversion in the opposite direction without re-typing anything.
Metric and Imperial: A Quick Background
The metric system (more formally the International System of Units) is built around powers of ten, which is why converting within it is so painless: a kilometre is exactly 1,000 metres, a metre is 100 centimetres, and a litre is 1,000 millilitres. Most of the world uses it for daily life. The imperial and closely related US customary systems grew out of older traditional measures and use less tidy relationships, such as 12 inches to a foot, 3 feet to a yard and 16 ounces to a pound. The two systems are still mixed together constantly: a country can sell petrol by the litre while measuring journeys in miles. This tool simply keeps the exact conversion factors on hand so you never have to remember whether a mile is 1.6 kilometres or the other way around.
Accuracy and Rounding
The converter stores precise conversion factors and does the maths at full floating-point precision, then rounds the displayed answer for readability. Very small results switch to scientific notation and very large ones to a compact format, so the number on screen stays legible. For everyday tasks the displayed figure is more than precise enough. If you are doing something where the last decimal place matters, such as engineering tolerances, medical dosing or financial calculations, treat the result as a strong starting point and confirm against an authoritative reference, because a rounded value is not the same as an exact one. Temperature is handled by formula rather than a single multiplier, since the Celsius and Fahrenheit scales have different zero points as well as different step sizes.
Tips for Getting It Right
- Check the direction: it is easy to convert the wrong way. If a number looks ten times too big or too small, you may have the input and output units reversed. The swap button fixes that instantly.
- Mind US versus UK gallons: they differ by about 20 percent, so always pick the right one for your recipe or fuel figure.
- Watch digital units: storage here uses 1024-based steps, which is why a drive sold as 1 terabyte can appear smaller once your operating system reports it.
- Estimate first: a rough mental approximation (miles are a bit more than 1.5 km, a kilo is a bit over 2 pounds) helps you spot a typo before you rely on the result.
How It Works in Your Browser
This converter is a single self-contained page. The conversion factors, the temperature formulas and the formatting all run as JavaScript on your own device the moment the page loads. Nothing you type is uploaded, and there is no server doing the calculation for you. Your recent conversions are kept only in your browser's local storage so you can glance back at them, and you can wipe that list at any time with the Clear History button. Because everything runs locally, the tool stays instant and keeps working even if your connection drops, and no record of what you converted is ever shared with QuickMerge or anyone else.
Next steps
Related tools
- convert a whole table of values — when you have more than a handful.
Browse all text and data tools, or see every QuickMerge tool.
Wondering how big a file this can take? We measured it: see Unit converter on the measured limits page, or the browser support matrix.
Frequently Asked Questions
Our conversions are highly accurate, using standardized conversion factors. For example, 1 meter equals exactly 3.28084 feet, and 1 kilogram equals exactly 2.20462 pounds. Temperature conversions use precise mathematical formulas.
Absolutely! All conversions happen locally in your browser. No data is sent to any server, and your conversion history is stored only in your browser's local storage.
Currently, we support standard units. For custom conversions, you can use our quick conversion buttons or manually calculate using the available units. Future updates may include custom unit support.
The two are genuinely different sizes. A US gallon is about 3.79 litres while a UK (imperial) gallon is about 4.55 litres, a difference of roughly 20 percent. That is why the volume category lists them separately. When you follow a recipe or read a fuel-economy figure, choose the gallon that matches the source so your result is correct.
The storage category uses the binary definition, so one kilobyte equals 1024 bytes, one megabyte equals 1024 kilobytes, and so on. This reflects how memory and many operating systems count storage. It is also why a drive advertised in decimal terms can appear slightly smaller once your computer reports its capacity.
Yes. The Area category covers square metres, square kilometres, square centimetres, square miles, square yards, square feet, acres and hectares — useful for room sizes, land plots and property listings. The Speed category covers metres per second, kilometres per hour, miles per hour, knots and feet per second — handy for vehicle speeds, weather reports, and nautical or aviation figures.
Use the swap button between the two unit dropdowns. It exchanges the input and output units instantly so you can read the conversion in the opposite direction without re-typing the value. It is the fastest way to check, for example, both how many feet are in a metre and how many metres are in a foot.
Your recent conversions are stored in your browser's local storage, which means they can persist on the same device and browser until you clear them. They are never uploaded anywhere. Use the Clear History button to wipe the list whenever you like, and remember that another browser or device will keep its own separate history.
Enter the value above and pick the two units, or read it off the charts. The three factors that cover most everyday cases are worth knowing by heart: 1 inch is exactly 25.4 mm, 1 pound is 453.592 g, and 1 litre is 0.264 US gallons. Everything else in the same family follows from those.
Metric units scale in powers of ten, so converting within the system means moving a decimal point. Imperial and US customary units use factors inherited from trade and craft — twelve, sixteen, 1,760 — with no pattern to derive. That is the whole reason a conversion chart is more useful than a rule here.
No, and this is the most common measurement mistake in recipes and fuel figures. A US gallon is 3.785 litres; an imperial gallon is 4.546 litres, about 20% larger. US and imperial pints and fluid ounces differ too, so a volume converted with the wrong one will be noticeably off.
You cannot, without knowing the density of the substance. Water is the convenient case — one litre weighs one kilogram — but flour, oil, sugar and soil all differ, some by a factor of two. A recipe that swaps cups for grams by assuming water will be wrong.
Because the two scales disagree about where zero sits as well as how large a degree is, so there is an addition as well as a multiplication: °F = °C × 9/5 + 32. That extra step is what makes it hard to do in your head, and why −40 is the one point where both scales read the same.
No. The conversion is arithmetic performed by JavaScript in your browser, so nothing you enter is transmitted or logged. That matters more than it sounds when the figures are from a lab notebook, a patient chart or an unreleased spec.
No — this page converts measurements only. Some file-conversion queries land here because of the shared word: for images use the image converter, for text into a PDF use text to PDF, and for a PDF into a spreadsheet start at image to Excel.