Micron (µ): The standard measurement for poly bag thickness. Amazon FBA requires poly bags to be at least 38 microns (1.5 mil) to prevent tearing. Standard cheap bags are often 25-30 microns.

Nautical Mile (nm): Used for international sea and air freight tracking. 1 nm = 1.15 regular miles. Essential if you are tracking container shipments from overseas.

Decimeter (dm): 10 Centimeters. Occasionally found in European dimensional specs for vintage furniture or artwork.

Fathom: 6 feet. Originally used to measure rope and water depth. You will see this on vintage nautical charts or antique rope listings.

Quintal (q): Exactly 100 kg (220 lbs). Used extensively in Europe and India for pricing agricultural goods like cotton, grain bags, or heavy raw materials.

Stone (st): 14 lbs. The standard unit for body weight in the UK and Ireland. If selling vintage scales, medical equipment, or clothing in the UK market, knowing "Stone" is helpful.

Dram (dr): 1/16th of an ounce. Used in apothecaries, vintage perfume bottles, and measuring gunpowder.

Hundredweight (cwt): 112 lbs (UK) or 100 lbs (US). A common unit for steel and scrap metal pricing.

Troy Ounce (ozt): 31.1 grams. The global trading standard for gold and silver. Warning: A standard kitchen scale measures "Avoirdupois Ounces" (28.35g). Do not sell gold using a kitchen scale or you lose 10% value.

Pennyweight (dwt): 1.555 grams. The standard unit used by US jewelers and pawn shops to buy scrap gold. 20 Dwt = 1 Troy Oz.

Tola & Baht: High-purity gold (22k-24k) from India (Tola = 11.66g) and Thailand (Baht = 15.24g) is sold by these units, never by the gram. Always verify the stamp.

Momme: The measure of Silk density. 19mm is standard high quality; 22mm is luxury; 25mm+ is heavy royal grade silk.

Cubic Foot (ft³): The "Magic Number" for USPS shipping. If a heavy box is under 0.5 cubic feet (approx 12x12x6), it qualifies for "USPS Cubic Pricing," which is often 50% cheaper than weight-based shipping.

Oil Barrel (bbl): 42 US Gallons. The standard unit for crude oil trading and industrial liquid storage.

Milliliters (ml): The global standard for perfume resale. Always calculate "Price Per ml" when selling partial bottles to determine fair market value.

Japanese (CM): The most accurate sizing system in the world because it measures the actual foot length in centimeters. If in doubt about a vintage shoe size, measure the insole in CM and use this tool.

Youth (Y): A "7Y" (Youth) is physically the same size as a "Men's 7." This allows you to cross-list high-value sneakers in both categories to reach more buyers.

UK vs US: A UK size is generally 1 size smaller than US Men's. (e.g., US 10 = UK 9). Always check the tongue tag to confirm.

Sq Yard: The standard unit for selling fabric, carpet, and flooring rolls. 1 Sq Yard = 9 Sq Feet.

Hectare (ha): 10,000 square meters. Used for land lots and agricultural property resale. 1 Hectare is approx 2.47 Acres.

Sq Feet: Essential for calculating the "Cost Per Foot" of your storage unit or warehouse space. If you pay $200 for a 10x10 unit, you are paying $2.00/sq ft.