Australian Decimal Coin Weight Tolerances


How much does my coin weigh? This is a common question first asked when a coin seems not quite right. Is it an error coin? Is the coin missing design or a part of the coin? Does it feel lightweight or too heavy? Does it sound different when dropped on the bench? Does the metal it’s made from appear different to normal? A coins weight must be accurately measured on a scale ideally to 2 decimal places. This is usually done a jewellers scale.

A coin has a legal parameter that it fits with regard to weight. A normal weight can differ up or down and still fit into the tolerance for a genuine coin. It can be handy to know these allowable tolerances as we examine coins closely. This is why we’ve compiled this handy guide to help collectors out. Information derived from Australian Currency Determinations for legal currency.


Decimal Coin Tolerances

CoinStandard Design Metal Composition ShapeEdgeDiameter (max) mmThickness (max) mmWeight gramsWeight Tolerance gramsWeight Minimum gramsWeight Maximum grams
1 Cent (1c) Feather Tailed Glider 97% Copper, 2.5% Zinc , .5% Tin Round Plain 17.75 1.80 2.60 +/- 0.3 2.30 2.90
2 Cent (2c) Frill-Necked Lizard 97% Copper, 2.5% Zinc , .5% Tin Round Plain 21.80 2.20 5.20 +/- 0.3 4.90 5.50
5 Cent (5c) Echidna 75% Copper, 25% Nickel Round Milled 19.53 1.90 2.83 +/- 0.33 2.50 3.16
10 Cent (10c) Lyrebird 75% Copper, 25% Nickel Round Milled 23.82 2.30 5.65 +/- 0.49 5.16 6.14
20 Cent (20c) Platypus 75% Copper, 25% Nickel Round Milled 28.65 2.92 11.30 +/- 0.78 10.52 12.08
50 Cent (50c) Coat of Arms 75% Copper, 25% Nickel Dodecagon (12 sided) Plain 31.65 3.16 15.55 +/- 0.96 14.59 16.51
One Dollar ($1) Mob of Kangaroos 92% Copper, 6% Aluminium, 2% Nickel Round Interupted Milled 25.20 3.46 9.00 +/- 0.66 8.34 9.66
Two Dollar ($2) Aboriginal Elder 92% Copper, 6% Aluminium, 2% Nickel Round Interupted Milled 20.62 3.70 6.60 +/- 0.6 6.00 6.60



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