Drawing the figures

A patent speaks with words, but many things are understood better by looking at them. The drawings of a patent, called figures, are not decoration: they are part of the text, and they follow precise form rules. On this page we see what they are for, when they are needed and how they are drawn, on an example you can look at: a telescope.

The rules quoted are those of the European Patent Convention (EPC), the European Patent Office (EPO) Guidelines and Italian legislation. The sources are listed at the end of the guide.

What figures are for

They show what the words describe. Three purposes, in order of importance.

1. Understanding. The reader, and first of all the expert who must be able to carry out the invention, sees how the parts are made and how they fit together. The invention must be disclosed in a manner sufficiently clear and complete for it to be carried out by a person skilled in the art (Art. 83 EPC; Art. 51, paragraph 2, of the Italian Industrial Property Code). A drawing often does this better than a page of text.
2. Linking. Every drawn part has a numeral, and the same numeral appears in the description and in the claims. The reader moves from text to figure without getting lost.
3. Interpreting. The extent of protection is determined by the claims, but the description and drawings are used to interpret them (Art. 69(1) EPC; Art. 52, paragraph 2, of the Code).

When they are needed

In a European application. The application contains any drawings referred to in the description or the claims (Art. 78(1)(d) EPC). In other words: if the text mentions a figure, the figure must be there. The description must then briefly describe the figures, if there are any (Rule 42(1)(d) EPC).

In an Italian application. The application must be accompanied by the drawings necessary to understand the invention (Art. 51, paragraph 1, of the Code). The Italian Patent and Trademark Office (UIBM) specifies that drawings are expected where they help clarify the subject of the patent, and that filing them is optional (UIBM, Contenuto della domanda).

In practice. If the invention is an object with parts and arrangements, a figure almost always helps. If it is a method, a flowchart can serve. Where words are enough on their own, you can do without, but it is worth asking whether a drawing would make the reading safer.

Form rules in force

Until 2023 the detailed rules on drawings were in a rule of the EPC. This is no longer so.

What changed. Rule 46 EPC, "Form of the drawings", was deleted by decision of the Administrative Council CA/D 10/22, in force from 1 February 2023 (Rule 46 EPC, deletion note). Today Rule 49(2) EPC says that the President of the EPO determines the presentation requirements of the documents making up the application. The EPO Guidelines summarise the practice in Part A, Chapter IX, and refer to the decision of the President of 7 July 2025 (Official Journal EPO 2025, A49) (EPO Guidelines, A-IX, 7.1).

What to read. On this page we summarise the Guidelines (Part A, Chapter IX), in the edition in force from 1 April 2026. Form rules can change, as the case of colour, which we see below, shows. Before filing, always check the version in force.

Where the figures go. In a European application all drawings are grouped on the sheets meant for drawings, and are not put into the description, the claims or the abstract, even if there is only one figure (EPO Guidelines, A-IX, 2.1).

What can be drawn

For the EPO all types of technical drawing count as drawings: perspectives, exploded views, sections, details on a different scale. Flow sheets and diagrams are drawings too, including functional diagrams and graphic representations of the relationship between two or more magnitudes (EPO Guidelines, A-IX, 1.1).

Photographs. The EPC makes no express provision for them. They are accepted where it is impossible to present in a drawing what is to be shown, and if they meet the requirements for drawings (EPO Guidelines, A-IX, 1.2). Photographs are numbered like drawings and briefly described in the description (A-IX, 1.2).

Sections. When a figure is a section of another, the latter indicates the position of the cut. Each section must be identifiable, for example with the words "Section on AB" or with a Roman numeral at both ends of the cutting line, equal to the Arabic numeral of the figure showing the section (EPO Guidelines, A-IX, 7.3.1). Cut parts are hatched with regularly spaced strokes, broken off where a numeral sits (A-IX, 7.3.2).

Lines, shading and colour

Lines. The thickness of lines must take into account the scale, the nature of the drawing and perfect legibility, including in reproductions (EPO Guidelines, A-IX, 7.1). Lines are drawn with drafting instruments, except those for which no instrument exists, such as irregular diagrams (A-IX, 7.1).

Black and white. Drawings are executed in black and white. Since 1 October 2025 colour and greyscale are also allowed, but only if the drawing is filed in electronic form. Drawings filed on paper or before that date are published in black and white (EPO Guidelines, A-IX, 7.1).

The advice. Always draw so that the black lines tell everything. If you use colour, do not build the description or claims on it, because a colour specification cannot always be reliably and objectively identified (EPO Guidelines, A-IX, 7.5.4).

Shading. It may be used if it helps to understand the figure and does not impede reading (EPO Guidelines, A-IX, 7.2).

No advertising. Drawings must not carry trademarks, advertising or references to a design or model, which are irrelevant and prohibited matter (EPO Guidelines, A-IX, 6, which refers to Rule 48 EPC).

Reference numerals

A reference numeral is a number written beside a part of the drawing and found again in the text. It is the thread that ties figure, description and claims together.

How to write them. Numbers and letters must be simple and clear, and not used with brackets, inverted commas, circles or outlines. So "26" is fine, "(26)" or a circled "26" is not. Signs such as 6' and 35'' are allowed (EPO Guidelines, A-IX, 7.5). The minimum height is 0.32 cm, so that a reduction to two-thirds stays legible (A-IX, 7.5.3). Preferably they are all laid out the same way up as the drawing, to avoid rotating the page (A-IX, 7.5).

Leading lines. They link the numeral to the detail. They must be as short as possible, start close to the numeral and reach at least as far as the detail indicated (EPO Guidelines, A-IX, 7.5.1). An arrow may end the line: a freestanding arrow indicates the entire section towards which it points; an arrow touching a line indicates the surface shown by that line (A-IX, 7.5.2).

The three consistency rules.

1. A numeral that appears in the drawing must also appear in the description or the claims, and vice versa (EPO Guidelines, A-IX, 7.5.4).
2. The same part has the same numeral in all figures and throughout the text (A-IX, 7.5.5).
3. In the description you give name and numeral together. Not "26 is connected to 28", but "secondary mirror 26 is connected to hexapod 28" (EPO Guidelines, F-II, 4.7).

In the claims. Technical features may be followed by the numeral in brackets, if this makes the claim easier to understand. The numerals do not limit the claim (Rule 43(7) EPC; Art. 21, paragraph 4, letter c), of Ministerial Decree 33/2010). For details see the page "Writing the claims".

If a part disappears. If you delete a figure, remove from the text the numerals that related only to it; if you delete a paragraph, remove from the drawing the numerals no longer described (EPO Guidelines, A-IX, 7.5.4).

In the example. The six numerals are the same throughout the file.

Numbering the figures

Figures are numbered consecutively in Arabic numerals, independently of the numbering of the sheets, preceded by the abbreviation "FIG", whatever the language of the application (EPO Guidelines, A-IX, 5.2). For example FIG. 1, FIG. 2, FIG. 3.

A few more rules (EPO Guidelines, A-IX, 5.2).

• If a single figure is enough, it is not numbered and the abbreviation "FIG" does not appear.
• The figure number is simple and clear, without brackets, circles or inverted commas, and larger than the reference numerals.
• Partial figures that form a whole may carry the same number followed by a capital letter, such as FIG 7A, FIG 7B.

Figures over several sheets. If a whole figure is split over several sheets, the parts must be able to be joined edge to edge without hiding anything (EPO Guidelines, A-IX, 5.3).

Orientation. As far as possible figures are set out upright on the sheet. If a figure is broader than it is high, it may be turned and the numbering goes on the right-hand side (EPO Guidelines, A-IX, 5.1).

In the brief description of the figures. You list the figures and say what each shows (Rule 42(1)(d) EPC). For the example: "FIG. 1 is a partial plan view of the telescope. FIG. 2 is an enlarged view of the area of the actuator (44)."

Text in the figures

Drawings must not contain text, except when absolutely indispensable, and then only a single word or a few words (EPO Guidelines, A-IX, 8). Where a word is indispensable, a space free of lines is left around it, for the translation (A-IX, 8).

What counts as indispensable. For circuit diagrams, block schematics and flow sheets, identifying catchwords for the functional parts of a complex system may be regarded as indispensable if they are needed to interpret the diagram rapidly and clearly (EPO Guidelines, F-II, 5.1).

Flow sheets. For the steps of a method the limit can be relaxed a little: a short sentence per step may be allowed, because the graphic part alone does not convey enough information (A-IX, 8).

Conventional symbols. Known devices may be shown with symbols of universally recognised meaning, if no further detail is essential. Other symbols are fine if they cannot be confused with existing ones, are simple and are explained in the description (EPO Guidelines, A-IX, 9).

Do not write part names. Names go in the description, linked to the numerals. In the drawing you put the numerals.

Scale and legibility

The two-thirds rule. If, at the chosen scale, all essential details would not be clearly distinguished after a linear reduction to two-thirds, the figure must be redrawn larger and, if necessary, split into partial figures (EPO Guidelines, A-IX, 7.4). Think of a reader who sees the sheet reduced or on a screen: if details are lost, they are of no use.

The scale. If a scale is shown, it must be graphic, that is a graduated bar, so that it stays valid when the drawing is reduced. Notes such as "scale 1:2" or "actual size" are not allowed (EPO Guidelines, A-IX, 7.4).

Proportions. Elements of the same figure must be in proportion to each other, unless a difference is indispensable for clarity. The preferred alternative is an extra figure with an enlargement of that part, with a finely drawn or dot-dash circle on the first figure to show where it is (EPO Guidelines, A-IX, 7.6).

Page. On paper, drawings are on A4 sheets with a usable area of no more than 26.2 cm by 17 cm, without frames, and with minimum margins of 2.5 cm at the top, 2.5 cm on the left, 1.5 cm on the right and 1 cm at the bottom (EPO Guidelines, A-IX, 3 and 4.1). The sheets of drawings are numbered in Arabic numerals, centred at the top, outside the top margin (A-IX, 4.2).

Reproduction. Drawings must allow electronic or direct reproduction; if filed electronically they must also have enough contrast to be clearly displayed at 300 dpi (EPO Guidelines, A-IX, 2.2).

Figures for methods and software

An invention is not always an object. For a method, a process or a program, the figures are usually diagrams.

• Flowchart: the steps of a method, one after the other, with arrows showing order and choices.
• Block diagram: the functional parts of a system and the connections between them.
• Graph of a quantity: a chart showing the relationship between two or more magnitudes.

They are all drawings in the full sense (EPO Guidelines, A-IX, 1.1). The same rules apply: reference numerals consistent with description and claims, numbered FIGs, text kept to a minimum, lines legible at reduced scale. For the steps of a method the text may be a little longer, a short sentence (A-IX, 8).

Why they matter. A method claim lists its steps. If the steps have a numeral in the drawing, the description can say "with reference to FIG. 3, in step 112 a measurement is taken…" and the link is immediate.

Tables and formulae. Chemical and mathematical formulae and tables may be included in the description, claims or abstract and do not follow the same requirements as drawings, unless they are submitted as drawings (EPO Guidelines, A-IX, 1.1).

Italian rules

For an Italian application, the implementing regulation of the Code (Ministerial Decree of 13 January 2010, no. 33) says:

• for paper filings, description, abstract, claims and drawings are printed indelibly with black lines and characters on strong white A4 paper, with margins of at least 2.5 cm on all four sides. The same formats apply if the text of the patent and the drawings are attached to an application filed online (Art. 22, paragraph 1);
• drawings may also be made by hand, are included in one or more sheets and are numbered progressively. The numbers of the drawings, and the numbers and letters that mark the various parts, must be referred to in the description (Art. 22, paragraph 3);
• the description briefly describes any drawings and describes at least one way of carrying out the invention with reference to the drawings, where present (Art. 21, paragraph 3, letters d) and e));
• in the claims, features may be followed by the numeral of the parts illustrated, and this does not limit the claim (Art. 21, paragraph 4, letter c)).

What we could not verify. In Articles 21 and 22 of Ministerial Decree 33/2010, which we read on the official Normattiva site, there are no rules on colour or on the electronic formats of drawings. We did not read the latest UIBM filing instructions: check them before filing in Italy. If you file with the EPO, the EPO rules summarised above apply.

Figures of the example

Two figures are enough for our telescope.

An optional FIG. 3, an exploded view, could show the parts pulled apart. It would be a choice, not an obligation.

The two figures use all and only the six numerals of the text and claims. If claim 3 mentions the blackened bolts (50), FIG. 2 must show them. If FIG. 1 showed a seventh part with a numeral not mentioned in the text, that numeral would have to be removed or explained (EPO Guidelines, A-IX, 7.5.4).

Two frequent mistakes, to avoid here. First: writing "actuator" next to the part instead of the numeral 44. Second: showing the actuator as 44 in one figure and as 45 in another, for the same part.

Checklist

Before considering the figures finished, answer these questions.

1. Does every figure mentioned in the text exist, and is every existing figure mentioned?
2. Does every numeral in the drawing appear in the text or the claims, and every numeral in the text in at least one figure?
3. Does the same part have the same numeral everywhere?
4. Are the figures numbered FIG. 1, FIG. 2, and so on?
5. Are the numerals simple, without brackets or circles, and at least 0.32 cm high?
6. Is there no text, apart from a few indispensable words?
7. When the sheet is reduced to two-thirds, can all details still be read?
8. Are the leading lines short and do they reach the detail?
9. Does the drawing work in black and white, even if you used colour?
10. Are there no trademarks, advertising or references to designs and models?

Before writing yours

This page is general information, not legal advice: no form rule guarantees that a patent will be granted or valid, and form rules can change. A real application should be reviewed by a patent attorney (mandatario). In the app this corresponds to the Drawings step.

Sources

1. Rule 42 EPC: https://www.epo.org/en/legal/epc/2020/r42.html (read on 2026-10-05)
2. Rule 43 EPC: https://www.epo.org/en/legal/epc/2020/r43.html (read on 2026-10-05)
3. Rule 46 EPC: https://www.epo.org/en/legal/epc/2020/r46.html (read on 2026-10-05)
4. Rule 49 EPC: https://www.epo.org/en/legal/epc/2020/r49.html (read on 2026-10-05)
5. A-IX, 1.1 Technical drawings: https://www.epo.org/en/legal/guidelines-epc/2026/a_ix_1_1.html (read on 2026-10-05)
6. A-IX, 1.2 Photographs: https://www.epo.org/en/legal/guidelines-epc/2026/a_ix_1_2.html (read on 2026-10-05)
7. A-IX, 2.1 and 2.2: https://www.epo.org/en/legal/guidelines-epc/2026/a_ix_2_1.html (read on 2026-10-05)
8. A-IX, 3 and 4.1 and 4.2: https://www.epo.org/en/legal/guidelines-epc/2026/a_ix_3.html (read on 2026-10-05)
9. A-IX, 5.1, 5.2, 5.3: https://www.epo.org/en/legal/guidelines-epc/2026/a_ix_5_1.html (read on 2026-10-05)
10. A-IX, 6 Prohibited matter: https://www.epo.org/en/legal/guidelines-epc/2026/a_ix_6.html (read on 2026-10-05)
11. A-IX, 7.1 Lines and strokes; colour: https://www.epo.org/en/legal/guidelines-epc/2026/a_ix_7_1.html (read on 2026-10-05)
12. A-IX, 7.2 Shading; 7.3.1 Sectional diagrams; 7.3.2 Hatching: https://www.epo.org/en/legal/guidelines-epc/2026/a_ix_7_2.html (read on 2026-10-05)
13. A-IX, 7.4 Scale: https://www.epo.org/en/legal/guidelines-epc/2026/a_ix_7_4.html (read on 2026-10-05)
14. A-IX, 7.5 and 7.5.1 and 7.5.2 and 7.5.3: https://www.epo.org/en/legal/guidelines-epc/2026/a_ix_7_5.html (read on 2026-10-05)
15. A-IX, 7.5.4 and 7.5.5: https://www.epo.org/en/legal/guidelines-epc/2026/a_ix_7_5_4.html (read on 2026-10-05)
16. A-IX, 7.6 Variations in proportions: https://www.epo.org/en/legal/guidelines-epc/2026/a_ix_7_6.html (read on 2026-10-05)
17. A-IX, 8 Text matter; 9 Conventional symbols: https://www.epo.org/en/legal/guidelines-epc/2026/a_ix_8.html (read on 2026-10-05)
18. F-II, 5.1 Drawings, form and content: https://www.epo.org/en/legal/guidelines-epc/2026/f_ii_5_1.html (read on 2026-10-05)
19. Art. 51 (Sufficient disclosure), art. 53 (Effects of patenting): https://www.normattiva.it/uri-res/N2Ls?urn:nir:stato:decreto.legislativo:2005-02-10;30~art51 (read on 2026-10-05)
20. Ministerial Decree 33 of 13 January 2010, art. 21: https://www.normattiva.it/uri-res/N2Ls?urn:nir:ministero.sviluppo.economico:decreto:2010-01-13;33~art21 (read on 2026-10-05)
21. Ministerial Decree 33/2010, art. 22 (Patent application): https://www.normattiva.it/uri-res/N2Ls?urn:nir:ministero.sviluppo.economico:decreto:2010-01-13;33~art22 (read on 2026-10-05)
22. UIBM, Content of the application: https://uibm.mise.gov.it/index.php/it/brevetti/brevetto-per-invenzione-industriale/deposito-di-una-domanda-di-brevetto/contenuto-della-domanda (read on 2026-10-05)