You might be wondering…

“Does the price always have to be an exact figure?”
“What kind of method of determination is considered sufficient under the law?”
“Do I risk invalidity if the price is set only by reference to market or usual price?”

My clients often ask…

“We’re entering into a supply contract where the price is based on the current price list. Is that valid?”
“I bought a machine, and the price was ‘by weight,’ but the calculation method is unclear. Is the contract valid?”

What the law says in a nutshell

• § 2080 Civil Code: The purchase price is determined with sufficient certainty if at least the method of its determination is agreed.

• § 2085(2) Civil Code: If the parties intend to conclude a contract without stating the price, the price is considered the usual price – that is, the price for which comparable goods are sold at the time and under similar conditions.

Practical significance of the rule

The law gives parties flexibility – a fixed amount is not necessary, as long as there is a clear and objectively ascertainable calculation method. Typical examples include:

• price by weight (e.g. “100 CZK/kg”),

• price according to the seller’s published price list,

• price based on stock exchange or market value,

• price determined by an expert opinion or inflation index.

Vague wording such as “price by agreement” or “price according to the seller’s possibilities” makes the contract invalid, because the method is not objective.

Common mistakes in practice

• Referring to a document that does not exist or is not accessible (e.g. “according to a price list to be issued later”).

• Leaving the price entirely at the discretion of one party (e.g. “according to the seller’s decision”).

• Treating the price as “just a detail” and omitting it, which may lead to disputes about validity.

How to proceed correctly

1. Set a clear calculation mechanism – weight, volume, price list, index.

2. Ensure that the source of calculation is objective and accessible to both parties.

3. If you don’t want to set the price at all, rely on § 2085(2) Civil Code – the usual price will apply.

4. Avoid wording that leaves the price entirely to one party’s discretion.

Practical examples

• Electricity supply contract – price “according to the current ERÚ tariff” is valid.

• Sale of timber – price “1,000 CZK per m³” is sufficiently certain.

• Sale of machinery – price “at the seller’s discretion” was ruled invalid, because the method was not objective.

Why “we’ll sort it out later” is risky

Courts insist that the price must be certain or at least ascertainable. If the price clause is vague, the whole contract risks invalidity. It is better to invest in a precise clause at the outset than face disputes later.

Lawyer’s recommendation

I advise buyers to always check that the price is set transparently and objectively. I advise sellers to avoid wording that leaves the price entirely up to them – courts may strike it down.

FAQ

Does the price always have to be an exact figure?
No, it is enough to clearly define the method for determining it.

What if no price is set at all?
Then the usual price under § 2085(2) Civil Code applies.

When is a price clause invalid?
If it is completely vague or left solely to the will of one party.