How to Convert Between Weight Units for Baking, Fitness, and Shipping
Weight conversion is one of the most common types of unit conversion people perform daily, often without realizing it. You might check your weight on a scale that reads in kilograms, read a recipe that lists ingredients in ounces, or calculate shipping costs based on pounds — all in the same afternoon. The world uses different weight systems depending on geography, industry, and tradition, making conversion skills practically indispensable.
The most widely used weight units are kilograms (kg) and pounds (lbs), but grams (g), ounces (oz), stones (st), and metric tons (t) each play important roles in specific contexts. Understanding how these units relate to each other saves time, prevents errors, and helps you communicate clearly in an increasingly globalized world.
The kilogram is the base unit of mass in the International System of Units (SI). Since 2019, it has been defined by the Planck constant, replacing the physical metal cylinder that served as the international prototype for nearly 130 years. One kilogram equals 1,000 grams. The metric system is used by virtually every country in the world for trade, science, and daily life.
Grams are ideal for smaller quantities — food packaging, jewelry, and medication dosages all commonly use grams. For very small masses, milligrams (1/1,000 of a gram) and micrograms (1/1,000,000 of a gram) are used in pharmaceutical and scientific contexts.
The pound (abbreviated "lb" from the Latin "libra") is the primary unit of weight in the United States. One pound equals 16 ounces. The avoirdupois pound, which is the standard pound used today, was standardized in 1959 when the United States and countries of the Commonwealth of Nations agreed that one pound would equal exactly 0.45359237 kilograms.
The stone is a unit used almost exclusively in the United Kingdom and Ireland for expressing human body weight. One stone equals 14 pounds or approximately 6.35 kilograms. So a person who weighs 154 pounds would say they weigh "11 stone" in the UK.
| From | To | Multiply By |
|---|---|---|
| Kilograms | Pounds | 2.2046 |
| Pounds | Kilograms | 0.4536 |
| Grams | Ounces | 0.0353 |
| Ounces | Grams | 28.3495 |
| Kilograms | Ounces | 35.274 |
| Ounces | Kilograms | 0.0283 |
| Stones | Kilograms | 6.3503 |
| Kilograms | Stones | 0.1575 |
| Pounds | Stones | 0.0714 |
| Metric Tons | Pounds | 2204.62 |
| Pounds | Metric Tons | 0.0004536 |
Baking is a science where precision matters. Unlike cooking, where you can often adjust ingredients by taste, baking requires exact measurements to achieve the right chemical reactions. This is why professional bakers worldwide prefer weight measurements over volume measurements.
A cup of flour can weigh anywhere from 120 to 150 grams depending on how it's scooped and packed — that's a 25% variance that can dramatically affect your results. Weighing ingredients eliminates this inconsistency. Here are common baking conversions:
| Ingredient | Volume | Weight (Metric) | Weight (Imperial) |
|---|---|---|---|
| All-purpose flour | 1 cup | 125 g | 4.4 oz |
| Granulated sugar | 1 cup | 200 g | 7.1 oz |
| Butter | 1 cup (2 sticks) | 227 g | 8 oz |
| Honey | 1 cup | 340 g | 12 oz |
| Cocoa powder | 1 cup | 85 g | 3 oz |
Weight management is one of the most common reasons people need to convert between units. Gym equipment in the US typically uses pounds, while most of the world's fitness apps and scientific literature use kilograms. When following an international workout program, you'll frequently need to convert.
For example, if a European training program prescribes lifting 80 kg on the bench press, that's about 176 lbs. A barbell in a US gym typically weighs 45 lbs (20.4 kg), and standard plates come in 2.5, 5, 10, 25, and 45 lb increments.
Body weight tracking presents its own conversion challenges. Many people track their weight in pounds but consume nutrition information labeled in grams. Understanding that 1 pound of body weight equals approximately 3,500 calories helps connect dietary choices to weight goals.
The shipping industry is perhaps where weight conversion has the most direct financial impact. International shipping costs are calculated based on either actual weight or dimensional weight (whichever is greater), and different countries use different units.
When shipping from the US to Europe, you'll need to convert pounds to kilograms. Most international carriers express rates in kilograms. A package weighing 5 lbs weighs 2.27 kg. For larger shipments, metric tons (1,000 kg) are the standard unit in global commodity trading and freight.
Dimensional weight adds another layer of complexity. Carriers calculate dimensional weight by multiplying the package's length × width × height and dividing by a dimensional factor (typically 5,000 for international shipments in cm/kg). This means a large but lightweight package (like a pillow) can cost more to ship than a small but heavy package (like a brick).
The most useful formula to memorize is the kg-to-lb conversion. For quick mental math, multiply kg by 2.2. To go from pounds to kg, divide by 2.2. These approximations are accurate to within 0.2%, which is sufficient for most non-scientific purposes.
Our free weight converter handles kg, lbs, oz, grams, stones, and more — no math required.
Use Weight Converter →Whether you're perfecting a sourdough recipe, tracking your deadlift progress, or calculating international shipping costs, weight conversion is a skill that pays dividends every day. Bookmark our converter tool for instant, accurate results whenever you need them.