Weight Converter

Table of contents:
This weight converter is a tool for converting between different units of mass. It includes a few units for casual interest but is mainly useful for converting between kilograms and pounds. However, more obscure scientific measures of weight can also be converted here.

Why So Many Units?

Units of measure are all completely arbitrary. There's no real reason why we have to use any one over another. They were all invented by individuals in diverse locations centuries before we had the worldwide communication structure to share common units. The metric system is the one that's touted above all others internationally, but even that's just a system of measurements subdivided into the power of ten, which makes calculations more convenient.

Even then, there is no reason for a kilogram to weigh as much as it does. We all just picked an amount, be it weight, length, or temperature and agreed we'd standardize on it. Meanwhile, the main competing system, imperial units, is notionally based on human body measurements like the thumb for an inch or a literal foot for a foot. However, cultures previously had diverse measurements, of course, so over time we standardized on an arbitrary length and declared it to be the standard measure.

As the World Wide Web has flourished around the world, there is a minor cultural movement to abandon antiquated measurement systems and standardize on a worldwide system, but this is more an optimistic goal to strive for someday. In the meantime, we need conversion calculators.

For that matter, weight is also arbitrary depending on where you are. It measures nothing but the resistance of a body against gravity; you will weight different amounts on Earth, the moon, Mars, and so on.

The Units:

Here is a chart showing the main units of weight this calculator converts for:


microgram (1e-6 grams)
milligram (1e-3 grams)
kilogram (1e+3 grams)
metric ton (1e+6 grams)


grain (1/7000th pounds)
drachma (1/16th ounce)
ounce (1/16th pound)
stone (14 pounds)
US ton (2000 pounds)
UK ton (2200 pounds)

As you can see, the metric system is a tidy and symmetrical progression while the imperial system is a random heap of odd ratios which aren't quite as convenient to convert from one to another. Note also, there is a distinction between units of measure and units of weight, even though "ounce" is also confusingly used to define a volume in the volumes system.

Using our calculator, you can easily save results in a column and compile a table of common weights and equivalents if you encounter this kind of problem frequently. Cooking in the kitchen is a frequent scenario where you might have to convert from milligrams to ounces, for instance.

A Brief History Of Units

The word "pound" is adapted from the ancient Roman measure "libra," which is why the abbreviation for pound is still "lb." It saw dual usage as both a measure of weight and force, similar to how we use "horsepower." The pound has been standardized since then and now refers strictly to 0.45359237 kilograms, while the kilogram = 2.20462 pounds.

Stones are an uncommon weight unit used primarily in the British isles. Naturally, the word comes from rocks, which were presumably chiseled to a standard size and compared on a balance scale. One stone is 14 pounds, so a 200 pound man weighs 14.286 stones, usually rounded off to say "weighing 14 stone."

The ounce is another ancient weight unit which became standardized lately. It is defined strictly in terms of the pound, being 1/16th of a pound.

As for the metric system, this was the first time in history that a complete decimalized system of weights and measures were engineered from scratch, to solve the "tower of Babel" problem of having so many different units of measure subdivided into so many odd bases. In the case of the kilogram, it is defined as a literal mass of a man-made artifact, a solid block of platinum-iridium, held in a laboratory in France.

These blocks were manufactured and distributed all over the world, with the idea of providing a physical constant upon which to calibrate measuring equipment such as a scale, then forever after have a standard unit.

There is currently an effort underway to define metric weights and measures by even more precise natural constants. For instance, the meter was originally one ten-millionth of the distance between the north pole and the equator, or exactly one forty-millionth of the circumference of the Earth. But in practice, it isn't very convenient to run a ruler from the north pole to the equator, so refined standards will take into account things like mathematical constants.

While there have been attempts made to standardize multiple measurements, units of time will always be difficult to bring into the metric system. This is because our definitions of time must be based on the position and movement of the Earth.

The trouble is, nature seems to be almost hostile to the idea of being quantified into neat, precise units. We have to cope with things like adding a leap day once every four years because the Earth revolves around the sun almost exactly once every 365.256 days. To adjust for further wobbles, we also have to add a "leap second" once in a while.

Scientific Definition of Weight

As mentioned before, weight and mass are related concepts, but weight is just the interaction of mass and gravity.

The scientist Galileo demonstrated concepts of gravity interacting with mass by dropping objects off the leaning tower of Pisa. From this and other scientific data, we also know that our concept of weight is actually a convenient notion we use for a shorthand reference point, to determine the mass of an object or body in the presence of a singularity (planet Earth), which exerts a force of 9.8 meters per second squared.

On other planets or other singularities, also called "gravity wells," your weight would be different. On the Earth's moon, your weight is just 16% of what it is on Earth, which explains why astronauts in lunar landings tend to bounce around slowly.

There is, as one might expect, an inherent problem with measuring weight in space. To take a measurement of weight in space, the mass is derived from a spring scale. On the ISS (International Space Station), this is how astronauts are weighed.

What To Do About Your Weight?

If you're here to convert your body weight, you're more than likely concerned about your mass. Maintaining a healthy standard body weight is an important health factor, this much is true. While the BMI (Body Mass Index) has been debunked lately as being a bit unrealistic, a weight measuring into the "obese" zone on the BMI is still cause for concern.

We can tell you this much: The only two words you need to know to lose weight are "diet" and "exercise," with perhaps a third word, "nonsense," which is what you call any weight loss plan that mentions anything else but the first two words.

There is no magic pill, magic skin cream, or magic corset that will make you lose body fat. Your weight is affected by exactly two factors, no more, no less: (1) How many calories you consume, and (2) how many calories you burn.

The myths associated with weight loss never seem to go away, but here's a list to debunk them one more time:

- "Spot reduction" of fat does not exist. You can't slim down your legs while leaving the rest of your body alone. It doesn't work that way; your body stores fat where it stores it, and burns it all at once from everywhere.

- There is no difference in calorie intake when it comes to the time of day. The notion is that eating a meal and going to sleep is worse than eating a meal in the morning and then jogging. As long as you count calories you eat per day and calories you burn per day, and you're not running a surplus, you will burn fat, regardless of when you eat.

- You can gain weight from surplus calories no matter where it comes from. Some people assume as long as you're eating healthy foods and avoiding junk foods, you won't gain weight. Calories from cake, steak, yogurt, celery, orange juice, and clam chowder are all the exact same calories once they get inside your body.

Outside of that, the whole story of your weight is told by the formula (calories consumed) - (calories burned). To your body, it's all just numbers!

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