Do you need to buy a whole Bitcoin? Understanding fractions and satoshis

No, you don't need to buy a whole bitcoin. One bitcoin divides into 100 million satoshis, and you can buy just part of one. The minimum amount doesn't depend on Bitcoin itself: it's set by the service you use.

Buying a fraction of a bitcoin: what does it mean?

The price you see everywhere is the price of one whole bitcoin. A bit like Gruyère priced by the kilo at the cheese counter: nobody concludes they have to walk out with a full kilo.

Bitcoin works the same way. If you buy CHF 50 worth, you get CHF 50 of bitcoin, in other words a fraction of one bitcoin. It's the same bitcoin the big holders own, just in a smaller quantity. Not a cut-price version.

Two checks all the same, and neither has anything to do with the size of your purchase. First, make sure you're buying actual bitcoin, and not a financial product that merely tracks its price: some brokers offer both. Second, as long as your bitcoins stay on a platform, it's the platform that holds them for you. The question is the same for 0.001 BTC as for 10 BTC.

And the satoshi? It isn't another cryptocurrency or a separate token. It's a unit of bitcoin, like the centime for the franc. Only the scale differs: a franc has 100 centimes, a bitcoin has 100 million satoshis. Bitcoin.org defines it as the smallest unit of bitcoin recorded on the blockchain. To save time, people often say "sats".

If someone offers you a "satoshi token" sold separately from bitcoin, that's not what we're talking about here.

How many satoshis are in a bitcoin?

Exactly 100,000,000. In fact the protocol counts in satoshis: in the code of Bitcoin Core, the network's reference software, every amount is a whole number of satoshis, and one bitcoin is defined as 100,000,000 of them. So a bitcoin divides down to the eighth decimal place.

To go from BTC to sats, multiply by 100 million. The other way, divide.

That's the whole point of sats: "1,000 sats" reads at a glance, whereas with "0.00001 BTC" you end up counting zeros.

How much bitcoin do CHF 10, 50 or 100 buy?

For the maths, let's take a fictitious price of CHF 100,000 for 1 BTC. It's a round number chosen for teaching purposes, not the current price. The real price moves all the time: to check it, use the Bitcoin converter, which also gives the result in sats.

The formula fits on one line: amount ÷ price = quantity of bitcoin. Then multiply by 100 million to get satoshis.

These results exclude fees. At this fictitious price, 1 franc is worth 1,000 sats, and 1 sat is worth a tenth of a centime.

Same exercise in euros, with another, equally fictitious assumption: 1 BTC = EUR 125,000. It's independent of the franc example, so don't read any euro-franc exchange rate into it.

• EUR 10 gets you 0.00008 BTC, or 8,000 sats.
• EUR 50 gets you 0.0004 BTC, or 40,000 sats.
• EUR 100 gets you 0.0008 BTC, or 80,000 sats.

Fees excluded again. What matters is the bitcoin price in the currency you pay with.

What is the minimum amount to buy bitcoin?

The question often mixes up four different things.

The protocol's divisibility. Bitcoin goes down to 1 satoshi, or 0.00000001 BTC. That's a technical limit, not an entry price: the satoshi is not a minimum purchase.

The platform's minimum purchase. Each service sets its own, in francs, euros or bitcoin, and can change it. Some accept small sums, others ask for more. The only reliable figure is on the service's pricing page, at the time you buy.

Fees. Commission, the gap between the price offered and the market price (the spread), a possible currency conversion. They can be fixed, proportional, or both. An example with fixed fees made up for the calculation, CHF 2 per purchase, and the fictitious price of CHF 100,000: out of CHF 10 paid, only CHF 8 is converted, or 8,000 sats. The fees eat 20% of your outlay. On CHF 100, the same CHF 2 weigh only 2%.

The withdrawal minimum. If you want to send your bitcoins to your own wallet, the platform may impose a minimum amount and sending fees. So you might buy a small sum, then have to accumulate more before you can withdraw it.

To compare the services available in Switzerland across the whole journey, from purchase to withdrawal, everything is covered in the guide Buying Bitcoin in Switzerland.

Does buying a small amount change the risk?

The amount at stake, yes. The way the price behaves, no.

If bitcoin drops 20%, your 100,000 sats drop 20% too, exactly like a whole bitcoin. With the fictitious price from earlier, your CHF 100 would become CHF 80. On the way up, the same rule applies in reverse.

A detail that often misleads: your number of satoshis doesn't move. It's their value in francs that changes.

So buying a little guarantees no profit. It only limits the sum at stake, and on that sum a significant loss remains possible.

One last point: on a small purchase, fees weigh more heavily, as we saw above. Look at what you actually receive, not just the percentage displayed.

Frequently asked questions

Where does the name "satoshi" come from?

From Satoshi Nakamoto, the pseudonym under which Bitcoin was created. People tend to write "sat" in the singular and "sats" in the plural, while BTC refers to one whole bitcoin.

Can you send a single satoshi?

On the blockchain, not in practice. Every transaction pays fees to the network, and they quickly exceed such a small amount. Above all, Bitcoin Core does not relay by default transactions that create outputs that are too small, known as "dust": amounts that would cost more in fees to spend than they are worth. Very small payments go through Lightning instead, a network built on top of Bitcoin.

Can the total number of satoshis increase?

No. The protocol caps issuance at just under 21 million bitcoins, or just under 2,100 trillion satoshis. Slicing more finely creates no new value: it's the same cake, cut into smaller pieces. To see what that represents per person on the planet, try Your share of the 21 million bitcoins.

Do I have to enter a quantity in BTC when I buy?

Usually not. Most services let you enter an amount in francs or euros and work out the matching fraction. Just check the final quantity received, once fees are deducted.

This article is for information only and does not constitute personalised investment advice. Bitcoin is volatile and a significant, or even total, loss is possible.

Back to the notebook