Patent drawing rules are the formal standards that the United States Patent and Trademark Office (USPTO) applies to the drawings filed with a patent application. Most of them sit in one section of Title 37 of the Code of Federal Regulations (CFR), 37 CFR 1.84. That section fixes the sheet size, the margins, the lines, the views, the shading and the numbering.
A compliant drawing is a black and white line drawing on A4 or US letter sheets, kept inside fixed margins. Every sheet, view and part is numbered in a set way. The drawing also shows every feature that the claims recite. A drawing that misses one of these points can attract an objection, and corrected sheets may then be required.
This guide sets out the patent drawing rules as a checklist. It also explains why patent drawings that look correct on the page are still objected to.
What the patent drawing rules cover
The requirement starts in the statute. Under 35 U.S.C. 113, an applicant must furnish a drawing where one is necessary for understanding the subject matter to be patented. Most patent applications therefore contain drawings.
The main patent drawing rules that follow from the statute sit in 5 sections of 37 CFR. Section 1.81 says when a drawing is required, and section 1.83 says what it must show. Section 1.84 sets the standards for how it is drawn. Sections 1.85 and 1.121 deal with corrections and with amended drawings filed during prosecution.
Section 1.84 applies in full to utility applications, and design drawings must comply with it as well. Design drawings have further requirements in 37 CFR 1.152.
Patent drawing rules checklist under 37 CFR 1.84
This checklist takes the patent drawing rules in the order of the regulation. Each heading names the paragraphs of 37 CFR 1.84 that the points come from.
Sheets and margins: 1.84(e), (f) and (g)
All sheets in an application are the same size, either A4 or US letter, with a short side at the top. The paper is white, flexible, strong, smooth, non-shiny and durable, and only one side is used. No frame is drawn around the usable area, which the regulation calls the sight.
| Requirement | A4 sheet | US letter sheet |
|---|---|---|
| Sheet size | 21.0 cm by 29.7 cm | 21.6 cm by 27.9 cm (8 1/2 by 11 inches) |
| Top margin, at least | 2.5 cm | 2.5 cm |
| Left margin, at least | 2.5 cm | 2.5 cm |
| Right margin, at least | 1.5 cm | 1.5 cm |
| Bottom margin, at least | 1.0 cm | 1.0 cm |
| Largest sight | 17.0 cm by 26.2 cm | 17.6 cm by 24.4 cm |
The drawing margins are minimums, and every figure stays inside the sight. Scan target points, which are small cross-hairs, should be printed on 2 diagonally opposite margin corners.
Lines and lettering: 1.84(a) and (l)
Black and white drawings are normally required, in India ink or an equivalent that gives solid black lines. Every line, number and letter is black, clean and well defined. Each one is heavy enough to reproduce well, including fine lines, shading and hatching. Lines of different thickness may be used in the same drawing where the difference has a meaning.
Views: 1.84(h), (i) and (j)
The drawing contains as many views as are needed to show the invention. They can be plan, elevation, section or perspective views, with enlarged detail views where needed.
- Views are grouped together, clearly separated and arranged without wasted space.
- No view is placed on another view or inside its outline.
- Views are not joined by projection lines and contain no centre lines.
- Views stand in the same direction and, where possible, upright. A wide view may be turned so that the top of the sheet is on the right-hand side.
- An exploded view shows the separated parts held together by a bracket.
- A sectional view is hatched with evenly spaced oblique parallel lines. A broken line on the parent view marks where the section is taken.
- A modified form of construction is shown in a view of its own.
- No view shares a sheet with the specification, the claims or the abstract.
- One view should be suitable for the front page of the patent.
Scale and shading: 1.84(k) and (m)
The scale is large enough for the drawing to stay clear when it is reduced to two-thirds of its size in reproduction. Notes such as “actual size” or “scale 1/2” are not permitted.
Shading is encouraged where it helps to show the shape of a part, mainly on spherical, cylindrical and conical surfaces. The light is taken to come from the upper left corner at 45 degrees. Solid black areas are not permitted, except in bar graphs or to represent colour.
Reference characters and lead lines: 1.84(p) and (q)
Reference characters are the numerals, or sometimes letters, that tie each part in the drawing to the description.
- Each character is at least 0.32 cm (1/8 inch) high.
- Characters are plain, with no brackets, inverted commas or circles around them.
- Characters do not cross lines and are not placed on hatched or shaded surfaces.
- The same part carries the same character in every view, and one character never marks 2 different parts.
- Every character in the drawings is mentioned in the description, and every character in the description appears in the drawings.
- Each character has a lead line that starts next to it and runs to the feature. The exception is an underlined character placed on the surface it marks.
- Lead lines are as short as possible and never cross each other.
Numbering and identification: 1.84(c), (o), (t) and (u)
Under the patent drawing rules, sheets and views are numbered separately, and the 2 sequences are independent of each other.
| Point | Sheet numbers | View numbers |
|---|---|---|
| Form | 2 Arabic numerals separated by an oblique line, such as 2/7 | “FIG.” followed by an Arabic numeral, such as FIG. 3 |
| Sequence | Consecutive, starting with 1 | Consecutive, starting with 1 |
| Size | Larger than the reference characters | Larger than the reference characters |
| Special cases | May move to the right-hand side if a figure comes too close to the top centre | Partial views of one figure share a number and add a capital letter, such as FIG. 3A |
The sheet number sits in the middle of the top of the sheet, inside the sight and not in the margin. Where an application has only a single view, that view is not numbered.
The title of the invention, the name of the inventor and the application or docket number may be placed in the top margin of each sheet. Text inside a figure is kept to as few words as possible.
Colour drawings and photographs
Black and white line drawings are the default under the patent drawing rules. In a utility application, the USPTO accepts colour drawings only after it grants a petition that explains why colour is necessary. The petition is accompanied by 3 items:
- The fee set in 37 CFR 1.17(h), which is USD 150, or USD 60 for a small entity and USD 30 for a micro entity (USPTO fee schedule, checked in October 2026).
- The colour drawings themselves: 1 set if they are filed through the USPTO electronic filing system, or 3 sets if they are not.
- An amendment that adds a standard statement on colour drawings as the first paragraph of the brief description of the drawings.
Design applications may contain colour drawings without a petition, but the same sets and the same statement are still needed. Colour drawings are not permitted in international applications filed under the Patent Cooperation Treaty (PCT).
Photographs are not ordinarily permitted either, and the USPTO accepts them only where a photograph is the only practicable way to show the invention. The regulation gives electrophoresis gels, blots, cell cultures, histological tissue sections and crystalline structures as examples.
Patent drawing requirements that depend on the claims
Most points in the checklist can be checked by looking at the drawing sheets alone. There are 2 patent drawing requirements in particular that cannot.
The first is in 37 CFR 1.83(a): the drawing in a non-provisional application has to show each feature of the invention that the claims specify. A conventional feature does not need a detailed picture, and a graphical symbol or a labelled box is enough. The feature still has to appear.
The second is the rule on reference characters in 37 CFR 1.84(p), which already appears in the checklist. The characters in the drawings and in the description must match in both directions, and each part keeps one character throughout.
Both of these patent drawing rules test the drawing against the text of the application. A person who has only the sketches or the computer-aided design (CAD) files cannot apply them.
A missing feature is also hard to repair later. A drawing submitted after the filing date cannot be used to overcome an insufficient specification, or to supplement the original disclosure in order to interpret the scope of a claim. No amendment may introduce new matter either. In general, a feature can therefore be added to a drawing after filing only where the application as filed already disclosed it.
Why filed drawings deviate from the patent drawing rules
The patent drawing rules are public, and drawings are still objected to. In Synoptic IP’s experience, the cause usually lies in how the drawings were prepared.
Drawings are often prepared by an illustrator whose training is in drawing alone. The illustrator receives sketches, photographs or CAD files with a list of figures, and returns clean sheets that respect the margins and the line rules. The illustrator often sees neither the claims nor the final description. Synoptic IP traces most of the drawing defects it sees to this gap. In its experience the illustrator has not been shown what the application claims, and a defect of this kind is simple to prevent.
The defects that follow from this gap include:
- a claimed feature that appears in no figure, because nobody told the illustrator that it was claimed;
- a reference character that the description uses for one part and the drawing uses for another;
- characters left in the drawing for parts that the description no longer mentions after a late edit;
- views that show the product well, but do not show how 2 claimed parts engage each other.
The picture is different when the illustrator works alongside the team that drafts the application and researches the technology. An illustrator who has read the draft has a firmer grasp of the invention, and can see what each figure has to support in the claims and the specification. The views are then chosen for the claims, and the numbering is checked against the text before filing.
Synoptic IP therefore recommends an illustrator who knows the application, its claims and its specification as thoroughly as the drawing standards. In practice, this means preparing utility patent drawings from the draft claims, and not from the sketches alone.
Example: a hinge with a hidden detent
The following example is an illustration and does not describe a real project.
An applicant sends an illustrator 6 CAD screenshots of a folding hinge and asks for 6 figures. The illustrator returns 6 clean sheets with correct margins, figure numbers and lead lines.
Claim 1, which the illustrator never saw, recites “a detent that holds the arm at 90 degrees”. The detent is a small ball inside the hinge barrel, and no screenshot shows it. The description also calls the spring “biasing member 24”, while the drawing uses 24 for the hinge pin.
The sheets comply with the formal patent drawing rules on margins, line quality and figure numbers. The drawing still fails 37 CFR 1.83(a) and 1.84(p). An illustrator who had read the claim would have asked for a sectional view through the barrel. A single read of the description would have exposed the mismatch in reference characters.
How the USPTO enforces the patent drawing rules
The USPTO checks drawings at 2 points, before examination and during it.
First check: before examination
The Office of Patent Application Processing (OPAP) first reviews the drawings of a new utility or plant application to see whether they can be scanned and reproduced for publication. Under section 507 of the Manual of Patent Examining Procedure (MPEP), OPAP may object to drawings for reasons such as:
- lines that are too light, or text that is illegible;
- lead lines that are missing;
- excessive text, or text that is not in English;
- inadequate margins, or paper of the wrong size;
- several figures that are not each labelled with a figure number in consecutive Arabic numerals;
- photographs that could have been drawings and are illegible after scanning;
- colour drawings or colour photographs filed without a petition.
OPAP then sends a notice that requires corrected drawings within a set period, which is usually 2 months.
Second check: the examiner
The examiner makes the second check during examination, and this is where the claims are compared with the figures. Where the drawings do not show every claimed feature, the examiner requires additional illustration and allows at least 2 months for it. Patent drawing objections of this kind usually arrive in an Office action, and the corrected sheets are filed with the response to the Office action.
Replacement sheets and time limits
Corrections are filed as new sheets, because the USPTO does not release drawings for correction. Each amended sheet is labelled “Replacement Sheet” in the top margin. It includes all the figures that were on the earlier version of that sheet, even if only 1 figure has changed. A sheet with an added figure is labelled “New Sheet”, and the changes are explained in the remarks or in the drawing amendment.
In a utility or plant application, an objection to the drawings is not put on hold unless the Office action says so. If a corrected drawing is still required when the application is allowed, the notice of allowability can set a period of 3 months that cannot be extended. The application is abandoned if no compliant drawing is filed in that time.
The periods in this section come from 37 CFR 1.83 and 1.85 and from MPEP 507, as checked in October 2026.
Formal requirements of this kind are not limited to drawings. The information disclosure statement has its own timing rules and fees, which a separate guide covers.
Design patent drawings: what differs
In a design application the design patent drawings carry more weight, because they show the claimed appearance itself. They follow the same patent drawing rules in 37 CFR 1.84 and add the requirements of 37 CFR 1.152.
The design needs enough views to disclose its complete appearance. Surface shading should show the character and contour of each surface, and solid black shading is allowed only to represent the colour black or colour contrast. Broken lines may show visible environmental structure, but they may not show hidden planes or surfaces that cannot be seen through opaque material.
A design has 2 further limits. A part may not be shown in alternate positions by full and broken lines in the same view. Photographs and ink drawings may not be combined as formal drawings in one application.
Patent drawings prepared to the USPTO rules
Synoptic IP prepares utility and design drawings for US applications in line with the patent drawing rules in 37 CFR 1.84. To receive a quote, send us the sketches, the draft claims and the description through our patent drawing and illustration page.
This guide is general information and is not legal advice.
Frequently Asked Questions
Is a drawing required in every US patent application?
No. Under 35 U.S.C. 113, a utility application needs a drawing only where one is necessary for understanding the subject matter to be patented. Where the invention can be illustrated and the applicant has filed no drawing, the USPTO may still require one. A design application is the exception, because it always needs a drawing or a photograph of the design.
What paper size is used for USPTO patent drawings?
The patent drawing rules allow 2 sheet sizes at the USPTO: A4, which is 21.0 cm by 29.7 cm, and US letter, which is 21.6 cm by 27.9 cm. All drawing sheets in one application must be the same size, with a short side at the top.
Do patent drawings have to be drawn to scale?
No, a fixed scale is not required. The patent drawing rules ask only for a scale at which the mechanism remains clear and uncrowded after the drawing is reduced to two-thirds of its size. Notes such as “actual size” are not permitted on the sheets.
Can hand-drawn patent drawings be filed at the USPTO?
Yes. The patent drawing rules require no particular software or method. They require a process that gives the drawing satisfactory reproduction characteristics, which means solid black, clean and uniformly thick lines inside the margins. The USPTO guide for utility applications says that hand-drawn figures should be scanned to PDF for electronic filing.
Can patent drawings be corrected after filing?
Yes, a drawing that breaks the patent drawing rules can normally be corrected. The applicant files new sheets labelled “Replacement Sheet” or “New Sheet” in the top margin and explains the changes. The correction cannot add new matter, so a feature that the application as filed did not disclose cannot be drawn in later.
Can US patent drawings be reused for a PCT application?
Often, but not in every case. PCT Rule 11 requires A4 sheets, the same minimum margins as 37 CFR 1.84 and black lines without colouring. Drawings prepared on A4 paper in black and white can often be adapted for both filings. Drawings on US letter paper, or drawings in colour, should be reworked before they are filed in an international application.
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