USPTO Drawing Standards

Drawings Required in Patent Applications 37 CFR § 1.81

• Drawings must be included in a nonprovisional application when necessary for the understanding of the invention. If drawings are essential to convey the invention but are not filed, the application will be considered incomplete.

• The original drawing(s) should be retained by the applicant in case future corrections are needed.

• If the applicant has not provided a drawing, the examiner will require submission within a time period of at least two months from the date the notice is sent.

• Drawings submitted after the filing date of the application:

  • Cannot be used to fix insufficient disclosure in the specification.

  • Cannot be used to supplement or interpret the original disclosure for determining the scope of any claim.

Content of Drawings

• General content requirements: 37 CFR § 1.83(a)

  • Drawings in a nonprovisional application must show every feature of the invention specified in the claims.

  • Conventional features (if not essential for understanding the invention) should be shown using graphical symbols or labeled representations (e.g., a labeled rectangular box).

  • Tables included in the specification and sequence listings should not be duplicated in the drawings.

• Improvements on existing machines 37 CFR § 1.83(b)

  When the invention is an improvement on an existing machine:

  • The drawing must, when possible, show the improved portion separately.

  • It must also include a view of only as much of the old structure as is necessary to show how the invention connects to it.

• Examiner requirements 37 CFR § 1.83(c)

  • If the drawings do not meet the requirements of (a) and (b), the examiner will require additional illustrations.

  • The applicant will have at least two months from the date of notice to respond.

  • Corrections must comply with the requirements of § 1.81(d).

Categories of Drawings 37 CFR § 1.84(a)

• Black and White Drawings (required for most applications): 37 CFR § 1.84(a)(1)
  Must use India ink or equivalent to produce solid black lines.

• Color Drawings (allowed only with petition): 37 CFR § 1.84(a)(2)

  • Permitted in design patents; rare in utility patents.

  • Requires petition with:

    • Explanation of necessity

    • Petition fee (§1.17(h))

    • 1 (electronic) or 3 (paper) sets of drawings

    • Specification must state:
      “The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.”

  • Not allowed in international (PCT) applications.

Photographs 37 CFR § 1.84(b)

• Black & White Photographs: 37 CFR § 1.84(b)(1)

  • Only if drawings are impractical (e.g., microscope images, gels).

  • Examiner may still require drawings.

• Color Photographs: 37 CFR § 1.84(b)(2)

  • Allowed only if color is essential and under same conditions as B&W photos.

Drawing Identification 37 CFR § 1.84(c)

• Each sheet must show (in the top margin):

  • Title of the invention

  • Inventor's name

  • Application number or docket number (if any)

• Post-filing drawings must be labeled:

  • “Replacement Sheet”

  • “New Sheet”

  • “Annotated Sheet” (if with annotations)

Specialized Graphic Forms 37 CFR § 1.84(d)

• Chemical formulas, tables, waveforms: treated as drawings.

  • Formulas: Separate figure numbers, brackets for clarity

  • Waveforms: Common vertical axis; time on horizontal

Paper Requirements 37 CFR § 1.84(e)

• Quality: White, durable, smooth, non-glossy, one side only

• Condition: Free of folds, creases, wrinkles, etc.

• Only one side may be used

Paper Size 37 CFR § 1.84(f)

• Acceptable sizes:

  • A4 (21.0 × 29.7 cm) 37 CFR § 1.84(f)(1)

  • U.S. Letter (21.6 × 27.9 cm) 37 CFR § 1.84(f)(2)

Margins 37 CFR § 1.84(g)

• Top: 2.5 cm (1 inch)

• Left side: 2.5 cm (1 inch)

• Right side: 1.5 cm (5/8 inch)

• Bottom: 1.0 cm (3/8 inch)

• No frame around image area

• Should have scan target points (i.e., cross-hairs) printed on two cater-corner margin corners

• DIN size A4 - sight no greater than 17.6 cm by 24.4 cm (6 15/16" x 9 5/8")

• (8 1/2 x 11) - sight no greater than 21.6 cm by 27.9 cm

Views in Drawings 37 CFR § 1.84(h)

• As many views as necessary to show the invention

• All views must fit economically on sheets and be clearly grouped

• Views must not be connected by projection lines and must not contain center lines

• Waveforms of electrical signals may be connected by dashed lines to show the relative timing of the waveforms

• Exploded views: 37 CFR § 1.84(h)(1)

  • Show the relationship/order of assembly of parts.

  • Use brackets to embrace separated parts.

  • If on a sheet with another figure, the exploded view must be bracketed.

• Partial views: 37 CFR § 1.84(h)(2)

  • Used when a large device cannot fit entirely on one sheet.

  • Can be broken into partial views on one or more sheets if clarity is maintained.

  • Each partial view must be connectable edge-to-edge; no overlapping of parts.

  • Include a smaller scale view showing the whole and the positions of partial views.

  • Enlarged portions must be labeled as separate views.

  • (i) When views across sheets form a single complete view, they must be arranged to avoid overlap.

  • (ii) Long views may be split vertically on one sheet if the relationship is clear.

• Sectional views: 37 CFR § 1.84(h)(3)

  • Section plane indicated by a broken line on the source view.

  • Ends of the line must have:

    • Numerals matching the sectional view number.

    • Arrows to indicate viewing direction.

  • Hatching required:

    • Use oblique parallel lines, spaced clearly.

    • Must not obscure reference characters or lead lines.

    • Break hatching where necessary for clarity.

    • Use angles (ideally 45°), adjusted for clarity between adjacent parts.

    • Large areas may use hatching along the edges only.

    • Hatching types should indicate material differences conventionally.

• Alternate positions: 37 CFR § 1.84(h)(4)

  • Shown using broken lines in the same view if space permits.

  • Otherwise, use a separate view.

• Modified forms: 37 CFR § 1.84(h)(5)

  • Modified forms of construction must be shown in separate views.

View Arrangement 37 CFR § 1.84(i)

• Views must:

  • Not overlap

  • Face the same direction

  • Be split vertically (if needed) with clear alignment

  • Be readable left-to-right

Front Page View 37 CFR § 1.84(j)

• Must include a suitable figure for publication

• Applicant may designate a preferred figure number

Drawing Scale 37 CFR § 1.84(k)

• Must show detail even when reduced to 2/3 size

• Do not use “actual size” or “scale 1/2” markings

Lines, Numbers, and Letters 37 CFR § 1.84(l)

• Must be:

  • Durable, black, clearly defined

  • Uniformly thick and clean

• Varying line thickness acceptable if meaningful

Shading 37 CFR § 1.84(m)

• Encouraged to show 3D shapes

• Use thin, spaced lines (not solid black)

• Must not obscure reference characters

• Solid black allowed only in bar graphs or color indication

Symbols 37 CFR § 1.84(n)

• Use conventional or USPTO-approved symbols

• All symbols must be identified in the specification

Legends 37 CFR § 1.84(o)

• Descriptive text allowed if helpful

• Avoid excessive wording

Numbers, Letters, and Reference Characters 37 CFR § 1.84(p)

• General formatting: 37 CFR § 1.84(p)(1)

  • Use plain, legible reference characters—numerals are preferred.

  • Do not use brackets, quotation marks, or outlines (e.g., circles) around reference characters, sheet numbers, or view numbers.

  • All characters must be oriented in the same direction as the view to avoid rotating the sheet.

  • Arrange reference characters to follow the profile of the depicted object.

• Alphabet use: 37 CFR § 1.84(p)(2)

  • Use the English alphabet for letters, except where another alphabet is standard (e.g., Greek for angles, wavelengths, formulas).

• Size and placement: 37 CFR § 1.84(p)(3)

  • Characters must be at least 0.32 cm (1/8 inch) tall.

  • Must not interfere with the drawing—avoid overlapping with lines or placing them on hatched/shaded surfaces.

  • If necessary (e.g., indicating surfaces or sections), characters may be underlined, and a blank space may be left in hatching/shading for visibility.

• Consistency: 37 CFR § 1.84(p)(4)

  • The same part shown in multiple views must use the same reference character.

  • A reference character must not designate different parts.

• Description alignment: 37 CFR § 1.84(p)(5)

  • Only use reference characters mentioned in the description.

  • Do not include unmentioned reference characters in the drawings.

Lead Lines 37 CFR § 1.84(q)

• Must be:

  • Short, direct, non-crossing

  • Used for all reference characters (unless underlined)

  • Drawn like regular lines

Arrows 37 CFR § 1.84(r)

• Used to:

  • Indicate the entire section towards which it points 37 CFR § 1.84(r)(1)

  • Indicate the surface shown by the line looking along the direction of the arrow 37 CFR § 1.84(r)(2)

  • Show direction of movement 37 CFR § 1.84(r)(3)

Copyright and Mask Work Notices 37 CFR § 1.84(s)

• May appear below the figure

• Text height: 1/8 to 1/4 inch

• Must be limited to legally required language, such as:
  “© 2025 John Doe”

Numbering of Drawing Sheets 37 CFR § 1.84(t)

• Use consecutive Arabic numerals, starting with 1.

• Place the sheet number at the top center, within the sight area but not in the margin.

  • If the drawing interferes, place number at top right.

• Use format: Sheet Number / Total Sheets (e.g., 1/3, 2/3)

• Numbers must be larger than reference characters to avoid confusion.

Numbering of Views 37 CFR § 1.84(u)

• Number views separately from sheet numbers, starting with FIG. 1. 37 CFR § 1.84(u)(1)

• Use “FIG.” + Arabic numeral (e.g., FIG. 1, FIG. 2, etc.)

• Partial views: same number + capital letter (e.g., FIG. 2A, FIG. 2B)

• If only one view, do not number it or use “FIG.”

• View numbers must be: 37 CFR § 1.84(u)(2)

  • Simple and clear

  • Larger than reference characters

  • Not enclosed in brackets, circles, or quotes

Security Markings 37 CFR § 1.84(v)

• Allowed only outside the sight area

• Preferably centered in the top margin

Corrections 37 CFR § 1.84(w)

• Any corrections must be durable and permanent

No Holes in Sheets 37 CFR § 1.84(x)

• Applicants must not punch holes in drawing sheets

Design Drawings 37 CFR § 1.152

• General Requirements:

  • Must comply with the requirements of § 1.84.

  • Must include a sufficient number of views to fully disclose the appearance of the design.

• Surface Shading:

  • Use appropriate surface shading to show character and contour of surfaces.

  • Solid black shading is not allowed unless:

    • Used to represent the color black, or

    • Used to show color contrast.

• Line Usage:

  • Broken lines may depict visible environmental structure only.

  • Broken lines must not show hidden planes or surfaces behind opaque materials.

  • Alternate positions of design elements using both full and broken lines in the same view are not permitted.

• Drawing Media:

  • Photographs and ink drawings cannot be combined as formal drawings in the same application.

  • Photographs, if used instead of ink drawings, must:

    • Show only the claimed design,

    • Not disclose environmental structure.

EPO Drawing Standards

Rule 46 – Drawings in European Patent Applications

(1) Drawing Sheet Requirements

• Usable surface must not exceed 26.2 cm x 17 cm.

• No surrounding frames are allowed on the usable surface.

• Minimum margins:

  • Top: 2.5 cm

  • Left: 2.5 cm

  • Right: 1.5 cm

  • Bottom: 1 cm

(2) Drawing Execution Standards

• Use black, durable, dense, and uniformly thick lines with no coloring.

• Cross-sections must be indicated by hatching that does not obscure reference signs or leader lines.

• Drawings must remain legible when reduced to 2/3 size; if a scale is given, it must be graphical.

• Numbers, letters, and reference signs must be simple and clear—no brackets, circles, or quotes around them.

• All lines should be drawn with drafting instruments.

• Elements must be proportional, unless otherwise necessary for clarity.

• Minimum height for numbers and letters: 0.32 cm; use Latin and (if customary) Greek alphabets.

• Multiple figures may appear on one sheet.

  • If multiple sheets make up one figure, they must be arranged to allow full assembly without obscuring parts.

  • Figures should be in upright position or, if sideways, the top must face left.

  • Figures must be numbered consecutively in Arabic numerals, independently from sheet numbering.

• Reference signs in drawings must match those in the description and claims, and vice versa.

• Text is not allowed in drawings, except for a few essential keywords (e.g., “open”, “section on AB”), which must be placed so they can be easily translated without disturbing the drawing lines.

(3) Flow Charts and Diagrams

• Flow sheets and diagrams are considered drawings under this rule.

Chapter IX – Drawings (EPC Summary)

What Counts as a Drawing

• Technical drawings include perspectives, exploded views, sections, diagrams, flow sheets, etc. 1.1

• Chemical/mathematical formulae and tables may appear in the description or be submitted as drawings (with different formatting requirements depending on context). 1.1

• Photographs are allowed if drawings can't illustrate the invention but must follow the same format rules (color photos will be published in B/W). 1.2

Presentation and Grouping

• Drawings must be grouped on separate sheets and never embedded in the description, claims, or abstract. 2.1

• They must be reproducible by standard means (e.g. scanning, offset printing). 2.2

• Abstracts may include one figure (or exceptionally more) from the application—no custom figure allowed. 2.3

Paper Requirements 3

• A4 white, strong, matt, durable sheets (80–120 g/m²).

• Only one side used; no card or permanent bindings.

• Corrections must be permanent and non-doubtful (e.g., white fluid is acceptable if indelible).

Sheet Formatting

• Usable area: Max 26.2 cm × 17 cm. Margins: top/left 2.5 cm; right 1.5 cm; bottom 1 cm. 4.1

• Sheet numbering: Consecutive Arabic numerals, placed within the usable area (top center or right if needed). 4.2

Drawing Layout

• Orientation: Preferably upright; all figures on a sheet should align. 5.1

• Figure numbering: Arabic numerals with "FIG"; omit if only one figure. Partial figures may be labeled like "FIG. 7A". 5.2

• Whole figures split across sheets must be alignable and clearly related (e.g., using a smaller overview sketch). 5.3

Prohibited Matter

• Drawings must not contain advertising, irrelevant markings, or references to industrial designs/models per Rule 48. 6

Execution Standards

• Lines/Strokes: Black ink, clear, consistent thickness, drawn with instruments. 7.1

• Shading: Allowed if it improves clarity; must not hinder legibility. 7.2

• Section Lines: 7.3.1

  • Should indicate position and may indicate viewing direction.

  • Figure name "Section on AB" or by marking each end of cross-section line with a single Roman number.

    • "Figure 22 illustrates a section taken along the line XXII‑XXII of Figure 21"

• Hatching: Regular, legible, broken where references are inserted. 7.3.2

• Scale: Must remain legible after 2/3 reduction; graphical scale bars preferred over textual (e.g., “actual size” not allowed). 7.4

• Leading lines: Short, precise, styled like drawing lines. 7.5.1

• Arrows: 7.5.2

  • A freestanding arrow indicates the entire section towards which it points

  • An arrow touching a line indicates the surface shown by the line looking along the direction of the arrow.

• Text/Signs: 7.5.3

  • Minimum height: 0.32 cm.

  • Latin alphabet preferred; Greek allowed where conventional.

Text on Drawings 8

• Text should be avoided unless absolutely necessary for understanding (e.g., flow charts).

• When present, keep text brief and allow white space for translation.

Symbols 9

• Recognized conventional symbols are allowed to depict known devices.

PCT Drawing Standards

PCT Rule 11

General Presentation Requirements

• All parts of the application (request, description, claims, drawings, abstract) must allow direct reproduction (e.g., photography, microfilming).

• Sheets must be clean, flat, unfolded, and used only on one side.

• Sheets should be used in an upright position (short sides at top and bottom), unless otherwise specified.

Material & Paper Specifications

• Use A4-size sheets (29.7 cm × 21 cm).

• Paper must be flexible, strong, white, smooth, non-shiny, and durable.

• Each element (e.g., claims, drawings) starts on a new sheet.

• Sheets should be easily separable and rejoinable for reproduction purposes.

Margins

• Usable area: max 26.2 cm × 17 cm, no border frames

• Margins: top 2.5 cm, left 2.5 cm, right 1.5 cm, bottom 1 cm

• Margins must be blank, except:

  • Top left corner may show applicant’s file reference (within 1.5 cm from the top)

Numbering

• Sheets: consecutively numbered in Arabic numerals, centered at top or bottom, not in margins

• Line numbers: every fifth line recommended in description and claims (in left margin)

Drawings in the Text

• No drawings in request, description, claims, or abstract

• Chemical/mathematical formulas allowed in description and abstract

• tables allowed in description/abstract and claims (if necessary)

• Sideways placement of tables/formulas allowed (top must face left)

Text in Drawings

• Drawings must be text-free, except a few essential labels (e.g., “water”, “open”, “section AB”)

• Labels must be placed so they can be translated without interfering with drawing lines

Drawing Requirements

• Use durable black ink with dense, well-defined, uniformly thick lines

• No coloring

• Cross-sections must be shown with oblique hatching that doesn’t obscure reference lines

• Must remain clear when reduced to 2/3 size

• If a scale is shown, it must be graphical

• All text (numbers, letters, signs) must be:

  • Simple, clear, ≥ 0.32 cm in height

  • Latin alphabet, or Greek where customary

  • No brackets, circles, or quotation marks

• Lines should be drawn with drafting instruments

• Elements must be proportional, unless otherwise necessary for clarity

Figures in Drawings

• Multiple figures allowed per sheet, must be:

  • Separated and space-efficient

  • Preferably upright, or sideways (top to the left)

• Figures spanning multiple sheets must be assemblable without overlap

• Figures numbered consecutively in Arabic numerals, independent of sheet numbers

Reference Signs

• Must be consistent throughout the application

• Do not include signs in drawings unless mentioned in the description, and vice versa

• Strongly recommended to provide a reference sign list if many are used