Yes, but only just. Every Australian 20 cent coin ever issued, including the 1966 originals, is still legal tender, and ordinary 1966 platypus 20 cent coins do turn up in change. The Australian 1966 wavy baseline 20 cent coin is a different matter. It is a rare die variety, and genuine examples are almost never found in circulation today. This guide explains what the variety is, how to identify a 1966 wavy baseline 20 cent coin, what it sells for, and what to do if one turns up in a purse, jar or inherited collection.
Quick Answers
- The 1966 wavy baseline 20 cent coin is a die variety of the first Australian decimal 20 cent coin, identified by a wave in the base of the numeral "2" on the platypus side.
- About 58.2 million 20 cent coins were struck in 1966, but only a tiny fraction have the wavy baseline.
- Used examples have recently sold from roughly A$225 (Fine) to around A$395 (good very fine), while uncirculated examples have reached A$3,000 or more.
- A normal 1966 20 cent coin with a flat baseline is usually worth little more than face value.
- All Australian 20 cent coins remain legal tender, but a wavy baseline coin should be sold to a collector rather than spent.
What Is the Australian 1966 Wavy Baseline 20 Cent Coin?
Australia switched to decimal currency on 14 February 1966, and the 20 cent coin replaced the old florin. The reverse shows a platypus in water designed by Stuart Devlin, and the first obverse carries Arnold Machin's portrait of Queen Elizabeth II. The coin is round, reeded, made from 75% copper and 25% nickel, weighs 11.31 g and measures 28.52 mm across, according to the Numista catalogue entry.
The 1966 20 cent coin was struck at two mints. Numista records about 28.2 million coins from Canberra and 30 million from the Royal Mint in London. The wavy baseline variety comes from the London strike, where one of the dies had a small difference in the base of the "2", creating an upward curve and a matching dent in the water swirl above it.
PCGS has explained one theory for how it happened. Tony Byrne, a former Chief Numismatist of the Royal Australian Mint, suggested that a small round object lightly hit a working die before it was hardened. You can read the full background in the PCGS article on the 1966 Wavy 2 20 Cent. The variety is now counted among the best-known modern Australian coin varieties, alongside the 2000 Incused Flag 50 Cent and the 2000 Mule Dollar.
Are Australian 1966 Wavy Baseline 20 Cent Coins Still in Circulation?
In theory, yes. In practice, they are very rarely seen. Here is how the question breaks down:
- Legal tender: 20 cent coins are legal tender for payments up to $5 under the Reserve Bank of Australia's legal tender rules. Older platypus coins are not withdrawn, so a 1966 coin can still be spent.
- Ordinary 1966 coins: used 1966 20 cent coins are still found in change decades later, according to the Perth Mint's collector guide.
- Wavy baseline coins: the same guide notes that the variety is very seldom seen in any condition at numismatic auctions, which hints at how few exist and how few are likely to remain unrecognised.
Several things explain the scarcity. Only one die from the London run produced the variety. Collectors and dealers have searched change for years, and stories about the coin spread widely online, including social media videos and news articles such as this one from The Brag. Any coin that was recognised was probably pulled out of circulation long ago.
A practical rule: if a 1966 20 cent coin has a wave in the base of the "2", do not spend it. Even a worn example is worth far more than 20 cents.
How to Identify a 1966 Wavy Baseline 20 Cent Coin
Use good light and a magnifier of about 10x. The steps below follow the identification method described by the Perth Mint, Numista and PCGS.
- Check the date. Only coins dated 1966 can be the variety.
- Turn the coin to the platypus side and find the numeral "2" in the denomination.
- Look at the base of the "2". On a normal coin, both the top and bottom edges of the base are straight. On the variety, the upper edge has a visible wave.
- Check the water swirl just above the base. The variety shows a matching indentation in the swirl, and PCGS also describes a raised bulge beneath the wave.
- Look at the gap between the water swirl and the platypus head. Numista notes that Canberra coins show a gap, while London coins show a small gap or none. The wavy baseline variety is a London die, so a clear Canberra-style gap points to a normal coin.
- Confirm the specifications: 11.31 g, 28.52 mm and a reeded edge. Large differences can indicate damage, alteration or a non-matching coin.
- Compare with reference photos from reputable sources, such as the Australian Coin Collecting blog, before deciding.
Never clean the coin. Cleaning scratches the surface and usually lowers the value. For a faster first check, a photo-based scanner can help narrow down the coin and year; see how to identify a coin by image.
1966 Wavy Baseline 20 Cent Coin Value
Value depends mostly on condition. Published sale records from Sterling Currency show these recent prices, in Australian dollars:
- Fine: A$225 (sold December 2024).
- Good fine: A$320 (sold June 2025).
- Good very fine: A$395 (sold December 2024).
- About uncirculated: A$1,250 (sold September 2025).
- Choice uncirculated, PCGS MS64: A$3,250 (sold April 2025).
- Gem uncirculated, PCGS MS65: A$3,750 (sold September 2022).
The records come from the dealer's own sold listings. An international auction price gives a second data point: Numista lists a PCGS MS64 example that sold at Heritage Auctions in July 2023 for US$1,560 including the buyer's premium.
By contrast, a standard 1966 20 cent coin with a flat baseline is common. Numista's price guide puts typical examples from about US$0.10 in worn condition to roughly US$1.40 in uncirculated condition. Treat all figures as snapshots, since prices shift with demand, grading and the number of coins that reach the market.
What affects the price of a wavy baseline coin:
- Grade: sharp, unworn detail and original lustre command large premiums. To understand grading terms, read how coin grading works.
- Third-party certification: a PCGS or NGC holder confirms authenticity and grade, which tends to support higher prices at the top end.
- Clarity of the wave: a pronounced wave is easier to verify and easier to sell.
- Surface damage: scratches, corrosion, cleaning marks and edge knocks reduce value.
Other Valuable Australian Decimal Coins Worth Checking
The wavy baseline coin is part of a wider group of sought-after Australian varieties and rarities:
- 2000 Mule Dollar: a $1 coin struck with mismatched dies, widely seen as one of the great modern Australian errors.
- 2000 Incused Flag 50 Cent: a variety of the circulating 50 cent coin.
- 1966 round 50 cent coin: made from silver, and heavily hoarded in the years after decimalisation, according to the Perth Mint.
- 1983 and 1984 20 cent coins: struck for circulation, but almost the whole production was melted instead of released, so surviving examples are scarce, as noted on Numista.
For more Australian coins to look out for, see the Australian coin value checker guide, and to learn why year and mint matter, read what a mint mark is.
How to Check and Sell a Suspected 1966 Wavy Baseline 20 Cent Coin
- Photograph both sides in natural light, with the base of the "2" in focus.
- Compare the photo with reference images of both the wavy baseline and the normal 1966 reverse.
- Look up sold prices rather than asking prices, and match the grade as closely as possible. Saving links, photos and notes in one place helps, and a clipboard manager such as QuickPaste can keep them within reach.
- Have the coin assessed by a trusted Australian coin dealer or a grading service. The five signals dealers check explain what experts look for.
- Sell through a reputable dealer or auction house, and compare offers before accepting one.
Use Coin Gauge to Check Australian Coins Faster
Coin Gauge is built to give quick answers on coins found in change, jars and inherited collections.
- Identify coins by photo instead of searching through catalogues.
- See value estimates built on real market sales data.
- Check old, rare and foreign coins, including Australian decimal coins.
- Scan the first coin free.
- Use it on iPhone and Android.
An app is a good first filter, but rare varieties such as the wavy baseline should always be confirmed in hand by an expert. Download Coin Gauge on the App Store or get it on Google Play.
Frequently Asked Questions About the 1966 Wavy Baseline 20 Cent Coin
What is a wavy baseline 20 cent coin?
It is a 1966 Australian 20 cent coin with a wave in the base of the numeral "2" on the platypus side, caused by a flaw in one die used at the Royal Mint in London.
Are 1966 wavy baseline 20 cent coins still in circulation?
They are still legal tender, but genuine examples are very rarely found in change. Most have been recognised and removed by collectors, and ordinary 1966 20 cent coins are far more common.
How much is a 1966 wavy baseline 20 cent coin worth?
Recent dealer sales range from about A$225 for a Fine example to around A$395 for good very fine, A$1,250 for about uncirculated, and A$3,250 or more for choice uncirculated coins graded MS64.
How many 1966 wavy baseline 20 cent coins exist?
No official count exists. About 58.2 million 20 cent coins were struck in 1966, and only a very small proportion carry the wavy baseline.
Is a normal 1966 20 cent coin worth anything?
Usually very little. Common circulated examples are worth about face value, and uncirculated examples are worth a small premium.
Can I still spend a 1966 20 cent coin?
Yes, since it remains legal tender. If it has the wavy baseline, however, spending it would throw away its collector value.
Where should I sell a wavy baseline 20 cent coin?
A reputable Australian coin dealer or auction house is the safest route, ideally after the coin has been authenticated or graded by a recognised service.
What other Australian 20 cent coins are valuable?
Besides the 1966 wavy baseline, the 1983 and 1984 issues are scarce because almost the entire production was melted down, as noted by Numista.
Key Takeaways
- The Australian 1966 wavy baseline 20 cent coin is a rare die variety, not a separate coin design.
- The wave appears in the base of the "2" on the platypus side, with a matching dent in the water swirl.
- All 20 cent coins are still legal tender, but wavy baseline coins are very rarely seen in change.
- Used examples sell in the hundreds of dollars, and top-grade examples sell for thousands.
- Do not clean the coin, and have it checked by a dealer or grading service before selling.