RARE CHANGE / COINS / PLATE 11 · 20C · 1966 · ROYAL MINT, LONDON
1966 20c wavy baseline, and what it's worth
A 1966 Australian twenty cent coin whose platypus reverse shows a raised wave along the top of the base stroke of the 2 in 20, a variety of the ordinary 1966 20c.
We don't have a fair price for the 1966 20c wavy baseline yet. We show a price only when at least 5 confirmed single-item auction sales in one condition back it, and we have 12 in the last 10 years, spread too thinly.
Common coins and notes often sell in bulk lots, which can't be priced one item at a time. The checks below still tell you whether yours is the version collectors look for.
Updated 30 Oct 2026. Prices refresh after every new auction result.
Prices by condition
AUDWorn coins sell for less. Find the row that looks most like yours.
WornFine · 4 sales
Too few sales for a fair price
Lightly wornVery Fine · 1 sale
Too few sales for a fair price
Barely wornExtremely Fine · 4 sales
Too few sales for a fair price
Never usedUncirculated · 3 sales
Too few sales for a fair price
Recent sales
HammerHow to check yours
Each letter on the drawing marks where to look. A magnifying glass or your phone's zoom helps.
-
Check A: Does the top edge of the 2's base stroke rise in a visible wave instead of running straight?
Reverse, the flat bottom stroke of the 2 in 20- YES
- A clear upward bump along the top of the 2's base, with a raised swelling beneath it.
- NO
- The base of the 2 is straight and even along its top and bottom edges.
-
Check B: Does the water line just above the wave follow it with a matching shallow dip?
Reverse, the line of water directly above the base of the 2- YES
- The water line above bends in step with the wave, as on genuine examples.
- NO
- The water line runs normally even though the 2 looks wavy, which suggests a fake, often made by heating the coin.
-
Check C: Does the obverse read 1966?
Obverse (Queen's side), the date after AUSTRALIA- YES
- The date 1966 follows AUSTRALIA on the right side of the portrait.
- NO
- Another year.
The free photo checker is on its way.
Record
- Face value
- 20c
- Year
- 1966
- Mint
- Royal Mint, London
- About 30 million 1966 20c coins were struck at the Royal Mint in London. [1][4]
- The wavy baseline is found on London-struck 1966 20c coins. [4][5]
- How the wave came about has never been settled. [3][4]
- The platypus reverse is by Stuart Devlin. [1][2]
- The 20c is 75% copper and 25% nickel, weighs 11.3 g and is 28.65 mm across. [1][2]
Questions
How much is a 1966 20c wavy baseline worth?
There aren't yet enough single-item auction sales of the 1966 20c wavy baseline to give a fair price. We'll show one as soon as at least 5 sales in one condition back it.
How do I know if my 1966 20c wavy baseline is genuine?
Work through the checks above. They cover what genuine examples show and what altered or different versions don't. A photo can't prove a coin or note is genuine, so for a valuable find, ask a professional numismatist or a grading service before you sell.
Should I clean it?
No. Cleaning leaves fine scratches that collectors spot at once, and cleaned coins and notes sell for much less. Keep it as it is, in a paper envelope or a coin holder.
Sources
Every fact on this page comes from at least two independent sources. Prices come from our own record of auction results.
- Royal Australian Mint: Twenty Cents, read 29 Oct 2026
- Australian twenty-cent coin, read 29 Oct 2026
- The Perth Mint: How to identify rare wavy baseline 20 cent coins, read 29 Oct 2026
- CoinWeek: The 1966 Australian Wavy "2" 20-Cent, read 29 Oct 2026
- The Australian Coin Collecting Blog: 1966 Wavy Baseline 20 cent, read 29 Oct 2026