⚖️ Imperial Units Guide
Stone vs Hundredweight
The stone and the hundredweight are two rungs of the same ladder: 8 stone make one hundredweight (112 lb). One survived into the 21st century. The other did not. Here is the full hierarchy and why.
The Imperial Weight Ladder, Rung by Rung
The imperial avoirdupois system is a ladder where each unit is a whole-number multiple of the one below. The stone sits in the middle, and the hundredweight sits two rungs above it:
| Unit | Equals | In kg |
|---|---|---|
| Ounce (oz) | 1/16 lb | 0.02835 |
| Pound (lb) | 16 oz | 0.45359 |
| Stone (st) | 14 lb | 6.35029 |
| Quarter (qr) | 2 st = 28 lb | 12.70059 |
| Hundredweight (cwt) | 8 st = 112 lb | 50.80235 |
| Ton | 20 cwt = 160 st = 2,240 lb | 1,016.05 |
Every step is exact. That precision is why the system worked for centuries of commerce: a merchant could move up and down the ladder without rounding. For why the stone landed on 14 pounds specifically, see why a stone is 14 pounds.
The Trap: Long Hundredweight vs Short Hundredweight
The single most confusing thing about the hundredweight is that there are two of them. The British (long) hundredweight is 112 pounds, defined as 8 stone. The American (short) hundredweight is 100 pounds, defined as, well, a hundred pounds. The US simplified the unit in the 19th century; Britain kept the traditional 112.
The 12% difference matters in international trade. An American "ton" (short ton) is 2,000 pounds or 20 short hundredweight, while the British long ton is 2,240 pounds or 20 long hundredweight. A contract that says "per hundredweight" without specifying which one is ambiguous by 12 pounds per unit. This is one of the quiet reasons metric won in global commerce: a tonne is a tonne everywhere.
In stone terms: 1 long hundredweight = 8 stone exactly. 1 short hundredweight = 100 ÷ 14 = about 7.14 stone. The long hundredweight was designed around the stone; the short one was not.
Who Still Uses Hundredweight (and Why Stone Survived Instead)
In Britain, the hundredweight is effectively extinct in daily life. You will encounter it in three places: historical documents and literature, some corners of farming (livestock feed is occasionally still discussed per hundredweight by older farmers), and the abbreviation "cwt" on old machinery plates and in vintage catalogues.
In the United States, the short hundredweight is more alive: it is still used in agriculture and commodities trading (grain, livestock), where prices are quoted per cwt. But even there, nobody uses it for body weight.
Why did the stone survive while the hundredweight died? Scale. The stone (6.35 kg) is a human-sized unit: it describes people. The hundredweight (50.8 kg) describes sacks, and sacks went metric without sentiment. Units that measure the body persist; units that measure commerce get replaced. That is the same reason the pint survived for beer while the gallon faded. For the bigger picture of large weights, see stone vs tonne explained.
Frequently Asked Questions
How many stone are in a hundredweight?
Eight. One imperial hundredweight is 112 pounds, and 112 divided by 14 is exactly 8 stone.
What is the difference between a hundredweight and a stone?
The stone is the smaller unit (14 lb) and the hundredweight is the larger one (112 lb, or 8 stone). The stone survived in daily life for body weight; the hundredweight did not.
Is a hundredweight 100 or 112 pounds?
The British (long) hundredweight is 112 pounds. The American (short) hundredweight is 100 pounds. This is a common source of confusion in international trade.
Who still uses hundredweight today?
Almost nobody in Britain. It survives in some farming and livestock contexts, in historical documents, and in the US where the 100-pound short hundredweight is still used in agriculture and commodities.