USPTO Drawing Compliance and Requirements

Staying compliant with USPTO and PCT drawing rules is critical for avoiding needless objections. Below is a practitioner‑focused summary of the core requirements taken from the USPTO’s Manual of Patent Examining Procedure (MPEP) §1825 and related PCT Rules.

What counts as a drawing

• Flow sheets and block diagrams are considered drawings. See MPEP §1825, PCT Rule 7.1.

When drawings are required

• Drawings are required when necessary to understand the invention (PCT Art. 7; MPEP §1825).
• Even if not strictly necessary, applicants may include drawings; a designated Office can later require them within a reasonable time (not less than two months). See PCT Art. 7(2)(ii) and Rule 7.2.

Sheet size and margins

• Sheets should be A4 (29.7 cm × 21.0 cm); the usable surface for drawings must not exceed 26.2 cm × 17.0 cm.
• Minimum margins on drawing sheets:
  Top: 2.5 cm
  Left: 2.5 cm
  Right: 1.5 cm
  Bottom: 1.0 cm

See PCT Rule 11.5 and 11.6(c).

Words and lettering in drawings

• Text should generally be avoided; short indispensable catchwords are permitted (e.g., “open,” “closed,” or brief labels in circuits/flow sheets). PCT Rule 11.11.
• Lettering height must be at least 0.32 cm; use Latin (and where customary, Greek) alphabets. PCT Rule 11.13(h).

Line quality and conventions

• Use durable, dense black lines with uniform thickness; no colors. PCT Rule 11.13(a).
• Cross-sections use oblique hatching. PCT Rule 11.13(b).
• Drawings must reproduce clearly when reduced to two‑thirds size. PCT Rule 11.13(c).
• Keep elements in proper proportion unless a different proportion is indispensable for clarity. PCT Rule 11.13(g).

Figure layout and numbering

• Multiple figures can appear on a sheet; arrange without wasted space, preferably upright. If sideways, top should be at the left of the sheet. PCT Rule 11.13(j).
• Figures are numbered consecutively in Arabic numerals, independent of sheet numbering. PCT Rule 11.13(k).
• The same feature should carry the same reference sign across the application. PCT Rule 11.13(m).

Practical tips for PatViz users

• Generate monochrome line art suitable for A4 scaling; ensure labels meet minimum height.
• Prefer catchwords over long sentences in flowcharts; keep shapes and arrows crisp and uniform.
• Maintain consistent reference numerals across figures; export to PNG/JPG/SVG or Visio and place onto A4‑compliant templates before filing.

Source

For the full text, see the USPTO’s MPEP §1825 “The Drawings” and related PCT rules: uspto.gov MPEP §1825.