Weights and Measures

Your guide to how the key metrics and measurements for the art and antiques sector

  • ATG Reporter
A set of brass and mahogany scales by J. Hare, Birmingham, £35 at Brettels, Newport, September 2011.


Silver and other precious metals are traditionally weighed in Troy ounces.

One Troy ounce is equivalent to 31.1g.

The standard or avoirdupois ounce (used for weighing foodstuffs etc.) is equivalent to 28.35g.

Quick Converter: values approximate

 Troy-Metric  Metric-Troy
 1oz = 31.1g  1g = 0.032oz
 2oz = 62.2g  10g = 0.321oz
 3oz = 93.3g  50g = 1.6oz
 4oz = 124.4g  100g = 3.21oz
 5oz = 155.5g  250g = 8oz
 6oz = 186.6g  500g= 16oz
 7oz = 217.7g  750g = 24.07oz
 8oz = 248.8g  1kg = 32.1oz
 9oz = 279.9g
 10oz = 311g


1in = 2.54cm             1cm = 3/8in (approx)

1ft = 30.48cm            1m = 3ft 3,3/8in

Quick Converter: values approximate

 Imperial-Metric  Metric-Imperial
 1in = 2.5cm  1cm = 3/8in
 2in = 5cm  2.5cm = 1in
 3in = 7.5cm  30cm = 12in (1ft)
 4in = 10cm  50cm = 20in
 5in = 12.5cm  1m = 3ft 4in
 6in = 15cm  2m = 6ft 8in
 7in = 17.5cm  3m = 10ft
 8in = 20cm
 9in = 22.5cm
 10in = 25cm
 11in = 27.5cm
 1ft = 30cm
 2ft = 60cm
 3ft = 90cm
 5ft = 1.5m
 10ft = 3m

For smaller objects, such as coins and medals, metric measurement in millimetres is the norm. There are 10mm to 1cm, or about 25mm to 1in.

One mile is equivalent to 1.6km, so a 60kmh speed limit is (roughly) 40mph.


An engine turned silver 50ft tape measure by James Chesterman and Co, Sheffield 1919, £170 at Woolley & Wallis, Salisbury, January 2011.