Convert Weight from Grams to Stones (g to st)

Gram to Stone Conversion Formula

Example

Let's convert 5 Gram (g) to Stone (st).

Using the formula:

Therefore, 5 Gram (g) is equal to 0.0007873652220888485026 Stone (st).

How many grams are in one stone? One Stone (st) contains 6350.29318 Grams (g) — the inverse of the factor above. Multiplying by 0.00015747304441776970052 takes you from grams to stones; multiplying by 6350.29318 brings you back.

Put in words: one gram equals 0.00015747304441776970052 stones, so the gram is the smaller unit of this pair. Converting between them never changes the amount of weight being measured — only the size of the unit you count it in.

What is a Gram (g)?

A gram (g) is a base unit of mass in the metric system. The plural form is grams.

Where Did the Gram Originally Come From?

The gram was initially defined in 1795 by the French National Convention.

Its first definition was based on the mass of one cubic centimeter of pure water at the temperature of its maximum density, which is approximately 4 degrees Celsius (4 °C).

This practical, water-based definition was a revolutionary step toward a standardized and universal system of measurement, moving away from the inconsistent and often confusing units of time.

Grams vs. Ounces: What's the Difference?

A gram is much smaller than an ounce, the standard unit of mass in the imperial and US customary systems.

One ounce equals approximately 28.35 grams, which is why grams are preferred for scientific work and for measuring small amounts, such as spices or medicine.

The metric system's decimal structure (for example, 1,000 grams in a kilogram) also makes calculations simpler than in the imperial system.

How Is the Gram Defined Today?

Although the gram was once tied to water, it's no longer linked to any physical object.

Since 2019, the kilogram — and therefore the gram — is defined by a fundamental constant, the Planck constant (h).

That shift makes the unit stable and reproducible in any properly equipped laboratory, without relying on the old International Prototype of the Kilogram.

The Gram's Odd Position in SI

The gram is the unit people use, but it is not the one the system is built on. The kilogram is the SI base unit of mass — the only base unit whose name carries a prefix.

This is a historical accident with practical consequences. Because the base unit already contains "kilo", SI prefixes are stacked on the gram rather than the kilogram: a millionth of a kilogram is a milligram, not a "microkilogram". The rule to remember is that prefixes always attach to gram, so the ladder runs microgram → milligram → gram → kilogram → megagram, where a megagram is what almost everyone calls a tonne.

Grams in Cooking and Nutrition

The gram's dominance in the kitchen comes from a property the imperial system cannot match: it measures mass, not volume.

A cup of flour can vary by 20% depending on whether it was scooped or spooned and how much it has settled; 120 grams of flour is 120 grams every time. This is why baking recipes — where ratios decide whether a dough works — moved to grams long before general cooking did, and why kitchen scales displaced measuring cups in professional practice.

Nutrition labelling relies on the same unit worldwide. Macronutrients are declared in grams per serving or per 100 g, with sodium and micronutrients in milligrams and vitamins often in micrograms. The per-100-gram convention exists specifically so that two products in different package sizes can be compared directly, without arithmetic.

What is a Stone (st)?

The stone (st) is a unit of measurement equal to 14 pounds (lb).

It's part of the imperial system and is still commonly used in a few countries, especially for weighing people.

How Many Kilograms are in a Stone?

For use in international contexts or scientific applications, the stone is often converted to the metric system.

One stone is equal to exactly 6.35029318 kilograms (kg).

This precise conversion is used in international trade and science to ensure everyone is using the exact standard measurement.

Why is Body Weight Measured in Stone?

Although it's an older unit, the stone remains the primary unit of measurement for body weight in the United Kingdom and Ireland.

It's common to hear someone state their weight as a combination of stone and pounds, like "12 stone 6 pounds."

Where Did the Stone Unit Come From?

The stone traces its origins back to the medieval English wool trade, where a "stone of wool" referred to a standard 14-pound measure used for buying and selling.

Stones for other goods could vary in weight—for example, a stone of glass was just 5 pounds—but over time, the 14-pound stone became the official legal standard.

How the Stone Is Actually Written

The stone is almost never used on its own. Body weight in Britain and Ireland is quoted as stones and pounds, with the remainder written out rather than expressed as a decimal.

A person weighing 72 kg is "11 stone 4" — that is 11 st 4 lb, or 158 pounds — not "11.3 stone". Reading the decimal form as pounds is a common error: 11.3 st is 11 st 4.2 lb, close by coincidence, but 11.5 st means 11 st 7 lb, not 11 st 5 lb.

The conversions worth keeping to hand are:

• 1 stone = 14 pounds = 6.35029 kilograms
• 1 kilogram ≈ 0.157473 stone
• A useful mental check: 10 stone ≈ 63.5 kg, and each additional stone adds a little over 6 kg.

Where the Stone Is and Is Not Used

The unit's survival is unusually specific. It was removed from British trade use by weights and measures legislation, so nothing is sold by the stone — shop scales read in kilograms and grams.

What survives is personal and conversational use: body weight, and by extension the weight of livestock and sporting figures such as boxing and horse-racing weights. Medical records in the UK are kept in kilograms, but patients are routinely told their weight in stones and pounds because that is the number they recognise.

Outside Britain and Ireland the unit is essentially unknown. The United States, despite sharing the pound, does not use the stone at all — American body weight is quoted in pounds alone, which is why a US figure of "158 lb" and a UK figure of "11 st 4" describe exactly the same person.

Gram to Stone Conversion Table

Here are some quick reference conversions from Gram (g) to Stone (st):