Jack S. Emery, P.A. an Arizona professional corporation
Registered patent attorney, USPTO Reg. No. 38,869
Jack S. Emery, J.D., PhD
Member, State Bar of Arizona
Individual patent representation for research professionals
Practical Advice On Making Patent Drawings

In this post I offer a few tips for clients who like to make their own drawings.

The 'Quick Start' Version
The Longer Version
For those who want more of the details . . . .

There are two things that one must have in hand (in my opinion) before writing the “Description” part of a patent application. These are (1) the claims, and (2) the drawings. This is not to say that they have to be perfect or final - they will likely evolve during the drafting process. But every element of every claim has to be supported and enabled in the written description, and you can’t do that if you don’t know what the claims are. Also, the written description will refer to the various claim elements by their reference numbers (the numbers in the callouts in the drawings). The numbering has to be consistent, and there can’t be any “orphan” callouts (reference numbers that are in the drawings but not the description or vice versa).

Inventors often supply drawings that they have made, and sometimes a writeup describing their technology, both of which I encourage. Inventor-drawn figures can often be used in the patent application with little change, if attention is paid to a few simple rules. In this post I suggest a few “drawing do’s and don’ts”. These are based on USPTO rules for utility applications. In provisionals, the requirements are much more liberal. However, since I don’t recommend the practice of filing non-comprehensive provisionals except in certain unusual situations, you would still usually want to produce drawings that comply with the rules for utility applications.


Drawing tools. Use whatever drawing tools you find easiest. Hand-drawn figures are acceptable as long as they conform to the other requirements. Most tech inventors will likely prefer to use computer tools, which have the advantage that you can change things without having to redraw the whole page. For PC users, I suggest using Microsoft Powerpoint, which has drawing tools that are adequate for most simple drawings. If you need something with more horsepower, or don’t have Microsoft Office, paint.NET (http://www.getpaint.net) is excellent and free, albeit with a slightly steeper learning curve. Some inventors prefer more sophisticated software such as one of the CAD packages or Adobe Illustrator, and that’s fine, except that if it’s software I don’t have, I won’t be able to edit the drawings except as images, so if something needs to be moved, I’ll have to send it back to you to do it.

File formats. Provide drawings in an editable file format where possible. If you used Powerpoint, provide the drawings in ppt or pptx format, for example. Reason: often small changes (moving a callout line, for example) are required, easy in the original file, but much harder or impossible on an image file such as a pdf or jpg.

Photos. Provide photos if you have them. Some kinds of photos can be used routinely (e.g. pictures of gels, cell cultures, etc. - I won’t go through the whole list here, see 37 CFR 1.84 for more details.) Photos are usually not allowed for showing the structure of a device, or other aspects that can be readily shown in a line drawing. However, photos of a prototype are often a good place to start in making a line drawing; they can be traced, or converted to line drawings in software.

One object per figure. Limit each drawing figure to one object. Showing several distinct objects in one figure is not allowed.

One figure per sheet. Limit each drawing sheet to one figure. We will consolidate them onto fewer sheets after we’re sure which figures we will use.

Figure numbers. Label each drawing figure with a tentative figure number if desired, starting with Fig. 1 and numbering consecutively, but do so in a place where it will be easy to remove. We will put in the final figure numbers later.

Callout lines. Observe the following conventions regarding callout lines:

Reference (callout) numbering. Start reference (callout) numbering at 100 or higher. Avoid using one- or two-digit callout numbers. Patent specifications contain lots of things that are numbered - paragraphs, figures, claims, tables, etc. If the callout numbers are unique, it’s less confusing and much easier to search for them, verify that there are no orphans, etc.

Reference number size. Make reference numbers at least 1/8 inch high. Keep in mind that if you resize the whole drawing and make it smaller, the reference numbers will get smaller too.

Reference number grouping. (Helpful but not required) Group reference numbering logically. It is not required that numbers be consecutive. You can, for example, use numbers starting with 100 for one part of the invention, 200 for a different part, etc. It is also recommended to increment numbering by more than one, to make it easier to insert additional numbers if desired (i.e. use 100, 105, 110, etc. rather than 100, 101, 102, etc.).

Reference number consistency. This is important: number consistently. Each reference number must refer to one and only one object, and each object must have one and only one reference number, throughout all drawings. If the “engagement gear” is reference number 103 in Fig. 1, it must be reference number 103 everywhere it appears, and reference number 103 can’t be used for anything else. Therefore:

Reference number table. Build a table of reference numbers as you add callouts to the drawings. Ideally, this should be three columns: reference number, name of the object, and figure numbers of all figures where the object appears. (Give objects whatever tentative names you like - in the end, the names will need to match the names used in the claims, but we’ll take care of that later.)

Paper size and margins. Drawings must fit on 8.5 x 11 paper (or the European standard, A4), with margins not less than 1 inch on the top, left, and bottom. Obviously, computer images can be resized if necessary, but doing so often entails redoing all the callouts, so it’s easier to make the drawing the right size in the first place. The PTO allows a 5/8 inch margin on the right and 3/8 inch on the bottom, but I recommend staying with 1 inch all around. Reason: if you decide to file a PCT application, A4 paper is required, which is slightly narrower than 8.5 inches (it’s 21.0 cm, 8.5 inches is 21.6 cm) and the drawing can’t be wider than 17 cm, which is 6.69 inches. 8.5 minus 1 5/8 is 6.875 inches which would be slightly too large. Better not to push the envelope on this - if 6.5 inches isn’t enough, use landscape orientation.

Orientation. Use portrait orientation where possible. It is permissible to use landscape orientation, but preferable not to if it can be avoided.

Extraneous marks. Remove any smudges or extraneous matter. The PTO will reject drawings that are visibly smudged or have any extraneous lines, dots, etc., that are not properly part of the drawing. (This often occurs when copy-pasting from one graphic to another.)

Drawings in provisionals. For provisional applications, in addition to doing “proper” drawings, consider including material that would be questionable in a full utility application, such as photos. There are few restrictions on drawings in provisionals - basically, anything that you can get into a pdf will likely be acceptable. That way those items are available to be referred to if it becomes necessary to rely on the provisional for support.


Colors. Don’t use colors. It is possible to submit color drawings in certain circumstances, but it requires a petition, they can’t be filed electronically, and they can’t be used at all in PCT applications. See 37 CFR 1.84. The same goes for color photos.

Grey scales. Avoid using grey scales. Yes, you can sometimes get away with it, but line drawings are preferred. If you need shading, use spaced lines.

Text. Don’t put descriptive text in drawings. Use callouts instead (i.e. numbers). Descriptive text belongs in the written description, not in the drawings.

Erasures. Avoid erasures if drawing by hand. See above re smudges.

Type size. Don’t use small type. The PTO will absolutely reject and return drawings where the type is too small. A good rule of thumb is, make sure that all text of any kind in a drawing is at least 1/8 inch high. (This is a common problem with graphs copied-pasted from elsewhere - the axis markings are often too small.)

Fonts. Don’t use strange fonts. Everything in a patent application has to be converted to pdf format for e-filing, and the pdf documents have to have all fonts embedded. Stick to Arial or a similarly ubiquitous font.

Target lines. Don’t put in “target lines” (crossed lines at the corner margins to help scanner alignment). The PTO used to require this, and the rules still say that they “should” be used, but in practice modern scanners don’t need it and we file electronically anyway. And if they accidentally get shifted, they could be considered either a violation of the margins or an extraneous mark, depending on where they are.

Numbering sheets. Don’t number the drawing sheets or put in the page headers/footers. We will do that later, after we’re sure which drawings we’re using and in what order.

Finally . . .

Among the most common reasons for the PTO rejecting drawings are:

  1. Letters or numbers that are too small.
  2. Drawings that extend into the required margins.
  3. Smudges and extraneous marks.

What these have in common is that they are things that are easily checked by PTO clerical employees when the application is filed. If a problem is found, a notice is issued requiring the applicant to file replacement drawing sheets, which takes time and adds to the expense.

For further reference . . .


Copyright 2011-12 Jack S. Emery. License is freely given to reproduce site content provided authorship is acknowledged and URL or link to the source page are prominently displayed. The contents of this site are not legal advice (you probably knew that). Opinions expressed herein are those of the author(s). Readers are cautioned that some patent practitioners and/or tech transfer professionals would likely disagree with some of the ideas and opinions discussed in these pages. Also: patent law is complicated. The material on this site is intended to provide readers with insight into concepts that are true in general, but a knowledgeable reader will nearly always be able to think of exceptions. In dealing with their inventions and intellectual property, readers should exercise their own judgment, after consulting with a qualified professional. Readers are requested to please call any factual errors or concerns to our attention, and we will endeavor to address them appropriately.