International Patent Application – PCT Drawing Requirements

The PCT, or Patent Cooperation Treaty, is an international treaty that more than 150 countries have signed on to.

A patent filed and granted in one particular country only provides protection in that country. If an inventor wants protection for their invention in more than one country, they can file separate patent applications in each country, which can be expensive and time consuming, or they can file an international patent application using the PCT procedure and receive patent protection in a large number of countries with one application and one set of filing fees.

Rules for International Patent Applications

The regulations governing international patent applications under the PCT can be found on the website of WIPO (the World Intellectual Property Organization), here. As is the case for national patent applications, applications generally must include drawings. The physical requirements for the applications are found in Rule 11 of the regulations.

PCT Drawing Requirements

The PCT drawing requirements are very specific, so great care must be taken to comply with all applicable regulations. Failure to comply with all of the requirements can result in office actions that will delay the process of receiving your patent. In this section we review some of the key requirements of drawings in international patent applications.

PCT Drawing Page Size

PCT applications, including the drawings, must be A4 (29.7cm x 21cm). Receiving offices can accept applications on other size pages, but they must be on A4 when transmitted, so it’s simpler to submit them on A4 in the first place.

Separate Sheets

All elements of an international patent application must begin on a separate sheet, so the drawings must be on a separate sheet from the description, claims, etc.

PCT Drawing Margins

The PCT specifies different margins for drawings than for other pages, so care must be taken with margins. The usable area is not to exceed 26.2cm x 17cm. Minimum margins for pages including drawings are:

  • top:  2.5 cm
  • left side: 2.5 cm
  • right side: 1.5 cm
  • bottom: 1 cm.

Words in PCT Drawings

PCT drawings generally are not to include words unless absolutely necessary, and then it should be only a one word or very short phrase description, such as “water,” “steam,” etc. The PCT drawing font size is different than the requirements for the rest of the application, letters and numbers are to be a minimum of 0.32cm. Lettering of drawings is to be in the Latin alphabet, except the Greek alphabet may be used where customary.

PCT Drawing Line Requirements

All lines must be durable, black, dense and dark, without colorings.

Cross sections are indicated by oblique hatching.

Drawings must be at a scale such that they will still be easily readable at a 2/3 scale.

PCT Color Drawings

The PCT rules do not contain any provision for color drawings. Note that in the PCT drawing line requirements it specifies that lines shall be without colorings. If you believe color drawings are essential to convey your invention, they may be submitted, but it would be advisable to have a black and white version as well with the relevant colors indicated with words.

PCT Drawing Corrections

The rules specify that drawings must be “reasonably free from erasures.” They are also to be reasonably free from alterations, overwritings, etc. If you have had to make corrections to your drawings, do not submit something all marked up, rather submit a new clean drawing. Corrections after the application has been filed can be submitted on a replacement sheet.

PCT Drawings Replacement Sheets

Any replacement sheets or PCT replacement drawings submitted after the application has been filed must also comply with all of the same rules.


PCT drawing requirements are very strict. The rules we have discussed in this article are just a sample of the requirements, they do not include all of the requirements. Even small errors can result in an office action that will delay the granting of the application. Some drawings that may be accepted by a national patent office, such as the USPTO, may be rejected for failing to comply with some PCT requirement.

The best way to avoid such delays on an international patent application is to work with experts such as ourselves who are familiar with all the requirements and can make certain that your drawings will meet all requirements from the outset.

Contact us for any questions you may have about drawings for PCT applications, or for a quote for your drawings.