Is a larger coin always worth more?

Answer 1

That was once the case for coins that were all made from the same type of precious metals but it's no longer true in general.

At one time coins in most countries had to contain nearly their face value in some kind of metal. For example, a dime had to contain 10¢ worth of silver, a half-eagle had to be made of $5 worth of gold, and so on. So, for all the coins made of the same type of metal their sizes were in fact proportional to their value simply because they needed to contain proportional amounts of metal.

However if two coins were made of different metals, there was no possible way their sizes could be proportional. For example, old US cents had to contain a penny's worth of copper, a metal that's much less valuable than silver. That meant a cent was huge - about the size of a half dollar - compared to a dime even though it's worth only 1/10 as much.

As the prices of metals changed and people were willing to accept coins simply because of the denomination struck on them rather than for their intrinsic metal value, it became possible to issue coins whose relative sizes had nothing to do with their relative values. For example pennies were downsized to their current 19 mm diameter in 1857, making them about the same size as dimes. Similarly when nickels were first made in 1866 they were larger than dimes.

When the US eliminated silver from its coins during the 1960s there was no metal need to keep the same sizes, but by that time the huge number of vending machines, transit fareboxes, bank coin counters, etc. meant it was easier to keep the traditional sizes than force everyone to retrofit all their equipment. So today the dime and penny have almost the same value of metal in them but people recognize one as being worth a cent and the other as 10 cents.

As the Mint gradually introduces new coins they no longer follow the old size rules. Sizes can be chosen for convenience instead of metal value. That's why the "golden" dollar coins are actually smaller than half dollars.

Similarly other countries have changed sizes when new coins are introduced. For example the EU has 8 different coins. Instead of increasing in size from 1 cent to 2 euros, they're grouped by color. Coins only increase in size within each color group:

> The 1, 2, and 5 cent coins are copper-colored.

> The 10, 20, and 50 cent coins are brass-colored. They also increase in size, but the 10 cent piece is smaller than the 5.

> The €1 and €2 coins are bi-metallic and the €1 coin is smaller than the 50 cent coin.