USPTO vs EPO Patent Drawings: 9 Critical Differences

A client sends one set of figures and asks you to file in Washington and Munich. It sounds like one job. It is not. USPTO vs EPO patent drawings is a comparison between a codified federal regulation, a Presidential Decision the EPO can reissue at will, and — if the case travels by the international route — a PCT rule that is stricter than either. One of those three changed in October 2025 and another was deleted in 2023, which is why so much of the guidance circulating online is now wrong. Here is the current position, difference by difference.

USPTO vs EPO Patent Drawings: Three Rulebooks, Not Two

Most filing programmes that reach both the United States and Europe are not choosing between two sets of drawing rules. They are living under three. The USPTO applies 37 CFR 1.84. The EPO applies a Decision of the President of the EPO, read in practice through EPO Guidelines for Examination, Part A, Chapter IX. And if the European filing arrives through the international route, the drawings had to satisfy PCT Rule 11 first, at a point in time when nobody had yet decided which national offices the case would enter.

That third rulebook is the one that causes the trouble. A set of figures can be perfectly compliant in Munich today and still have been non-compliant as filed in Geneva eighteen months earlier, because the international phase locked in a stricter standard than either office applies on its own.

The nine differences below are the ones that actually generate objections, redrawing invoices and lost filing dates. They are ordered roughly by how much money they cost when missed.

• Source of authority — a codified rule in the US, a revisable Presidential Decision at the EPO
• Colour — petition and fee in the US, accepted electronically at the EPO since 1 October 2025
• Greyscale — awkward in the US, now expressly contemplated at the EPO
• Sheet size — A4 or US Letter accepted in Washington, A4 in practice in Munich
• Margins — fixed asymmetric minima by rule in the US
• Text in figures — legends tolerated in the US, near-banned under PCT Rule 11.11
• Photographs — exceptional in the US, assessed on reproducibility at the EPO
• View numbering — the literal abbreviation “FIG.” is required in the US
• Design rights — 37 CFR 1.152 surface shading has no EU equivalent

Rule 46 EPC No Longer Exists — What Actually Governs EPO Figures

Start here, because a large share of the drawing guidance published online is simply out of date. Rule 46 EPC, “Form of the drawings”, was deleted with effect from 1 February 2023, together with Rule 49(3) to (12) EPC. The deletion came out of the Administrative Council’s digital-transformation package agreed in October 2022.

Nothing was abolished in substance. The form and execution requirements for drawings were moved into a Decision of the President of the EPO issued under Rule 49(2) EPC and published in the Official Journal — the current instrument is dated 7 July 2025. The point of the move was institutional: the EPO can now adjust presentation requirements as filing technology changes without amending the Implementing Regulations.

For day-to-day work this means two things. First, if a vendor or a checklist still cites “Rule 46 EPC compliance”, that document has not been reviewed since 2022 and you should assume the rest of it is equally stale. Second, the practical working text is the Guidelines, Part A, Chapter IX — not the Implementing Regulations. Our note on EPO drawing requirements tracks the current position.

The contrast with the US side is structural rather than cosmetic. 37 CFR 1.84 is a codified regulation; changing it needs rulemaking. The EPO’s drawing standard now sits in an instrument the President can reissue. Anyone maintaining drawing templates across both offices should expect the European half to move more often, and should date-stamp their internal standards accordingly.

Colour and Greyscale: The Divergence That Opened on 1 October 2025

This is the single widest gap in the comparison, and it opened recently. From 1 October 2025 the EPO accepts drawings filed by electronic communication in colour or greyscale, provided they are sufficiently rich in contrast and suitable to be displayed clearly at 300 dpi. The concession is confined to the drawings; the description, claims and abstract remain black and white.

The USPTO has not moved with it. Under 37 CFR 1.84(a)(1), “India ink, or its equivalent that secures solid black lines, must be used for drawings”. Paragraph (a)(2) then provides that the Office “will accept color drawings in utility patent applications only after granting a petition filed under this paragraph” — which carries the fee set out in § 1.17(h) and requires an amendment to the specification referring to the colour drawings.

So the same figure set can be filed as-is in Munich and needs a granted petition, a fee and a specification amendment in Washington. For an applicant whose invention genuinely depends on colour — histology, thermal imaging, spectroscopy output, wiring looms identified by sheath colour — the sequencing matters.

There is a trap underneath this that catches experienced filers. The PCT was not changed. Rule 11.13(a) still requires drawings “executed in durable, black, sufficiently dense and dark, uniformly thick and well-defined, lines and strokes without colorings”. A colour figure is non-compliant as filed in the international phase regardless of what the EPO will later accept in a direct European filing.

For a Euro-PCT entry the EPO will work from colour only where the colour drawings are actually on PATENTSCOPE and the international publication reflects them. If the international phase flattened your figures to black and white, that flattened version is what the European phase inherits. More detail sits in our pieces on PCT drawing requirements and colour drawings at the EPO.

Practical rule: if a case may ever go through the PCT, draft the figures so that they read correctly in black and white, then add colour as an enhancement for the jurisdictions that will take it. Colour that carries information no greyscale rendering can convey is a disclosure risk in the international phase, not a feature.

Line Quality, Sheet Size and Margins Side by Side

On line quality the two offices are closer than the folklore suggests. 37 CFR 1.84(l) requires that “every line, number, and letter must be durable, clean, black… sufficiently dense and dark, and uniformly thick and well-defined”. PCT Rule 11.13(a) uses almost the same vocabulary. A figure drafted to satisfy one will normally satisfy the other, colour aside.

Sheet size is where the US is the more permissive of the two. Paragraph (f) accepts either “21.0 cm. by 29.7 cm. (DIN size A4), or 21.6 cm. by 27.9 cm. (8 1/2 by 11 inches)”. European practice is built around A4. If you standardise on A4 for everything, you are compliant in both places; if you standardise on US Letter, you have created a conversion step for every European filing, and conversion is exactly where margins get clipped.

The US margins are fixed by rule and they are asymmetric, which is the detail that gets missed. Under paragraph (g) a sheet needs “a top margin of at least 2.5 cm. (1 inch), a left side margin of at least 2.5 cm. (1 inch), a right side margin of at least 1.5 cm. (5/8 inch), and a bottom margin of at least 1.0 cm. (3/8 inch)”.

• Top: at least 2.5 cm (1 inch)
• Left: at least 2.5 cm (1 inch)
• Right: at least 1.5 cm (5/8 inch)
• Bottom: at least 1.0 cm (3/8 inch)

Two consequences follow. A template that applies a uniform 2.5 cm border is compliant but wastes usable sheet area, which pushes multi-figure sheets toward illegibility. And a template centred on Letter-sized paper, then rescaled to A4, will usually lose the bottom margin first. We set this out in full in USPTO drawing margins.

Cross-hatching is worth a line of its own. PCT Rule 11.13(b) requires that “cross-sections shall be indicated by oblique hatching which should not impede the clear reading of the reference signs and leading lines”. That is a legibility test, not a style test, and it is the most common reason a dense sectional view draws an objection in the international phase.

Reference Signs, Text in Drawings and View Numbering

Here the US rule is more prescriptive and the international rule is more restrictive — a combination that surprises people. On reference characters, 37 CFR 1.84(p) requires that they be “plain and legible, and must not be used in association with brackets”, and that they “must measure at least .32 cm. (1/8 inch) in height”. That is a hard number you can check in a drafting program.

The EPO’s requirement is expressed as legibility at reproduction scale rather than as a single figure in the Implementing Regulations, so the safe engineering choice is to meet the US 0.32 cm minimum everywhere and stop thinking about it. Consistency between the figures and the description matters more in European prosecution than the exact glyph height: a reference sign that appears in the drawings but never in the description invites an objection. Our note on patent drawing reference numerals covers the numbering discipline.

Text inside the figures is the genuine divergence. PCT Rule 11.11(a) states that drawings “shall not contain text matter, except a single word or words, when absolutely indispensable, such as ‘water,’ ‘steam,’ ‘open,’ ‘closed,’ ‘section on AB’”. US practice is materially more relaxed about descriptive legends.

This asymmetry is why block diagrams and flowcharts for software and process inventions are the hardest figures to harmonise. A US-style flowchart with a sentence in every box is non-compliant under Rule 11.11. The fix is to label boxes with reference numerals and carry the wording in the description, which reads as a downgrade to US attorneys and is the only version that survives the international phase.

View numbering is a small point with a literal answer. Paragraph (u) requires views to be “numbered in consecutive Arabic numerals, starting with 1” and that the number “must be preceded by the abbreviation ‘FIG.’”. Not “Figure”, not “Fig” without the stop. Drafting software defaults are a common source of this objection.

One formality applies in both systems and is easy to automate: every element given a reference sign in a figure should appear in the brief description of the drawings, and nothing should be referenced that is not shown. That reconciliation takes minutes and removes a whole class of office action.

Photographs: Barely Tolerated in One Office, Workable in the Other

The US position is restrictive by rule. 37 CFR 1.84(b) provides that photographs “are not ordinarily permitted”, and are accepted only where “photographs are the only practicable medium for illustrating the claimed invention”. That is a necessity test, and an examiner can and will ask you to justify it.

The European assessment turns on whether the reproduction is clear and suitable for publication rather than on whether a line drawing was theoretically possible. Since 1 October 2025 the greyscale allowance has made photographic subject matter considerably easier to file electronically at the EPO.

Where this bites in practice is micrographs, metallurgical structures, cell cultures and textile weaves — the subject matter where a line drawing genuinely loses the information. The workable strategy is a two-track set: a photograph where it is the only honest representation, plus a line-drawn schematic that carries the reference signs. The schematic satisfies the formality reviewer; the photograph satisfies the disclosure.

One 37 CFR 1.152 constraint catches design filers specifically: photographs and ink drawings must not be combined as formal drawings in a single application. A hybrid set is not a safe answer in a US design case.

Design Rights: 37 CFR 1.152 Versus the EU Registered Design

Design filings diverge further than utility filings, and the comparison is not really USPTO against EPO at all — EU registered designs are handled by the EUIPO, not the EPO, which is itself a frequent source of confusion in cross-border instructions.

On the US side 37 CFR 1.152 is short and demanding. The design “must be represented by a drawing that complies with the requirements of § 1.84 and must contain a sufficient number of views to constitute a complete disclosure of the appearance of the design”. Then the substantive part: “Appropriate and adequate surface shading should be used to show the character or contour of the surfaces represented. Solid black surface shading is not permitted except when used to represent the color black as well as color contrast.”

Broken lines carry a defined meaning: they “may be used to show visible environmental structure, but may not be used to show hidden planes and surfaces that cannot be seen through opaque materials”. Because broken lines disclaim what they depict, they are a claim-scoping tool, and a draftsperson who converts them to solid lines has narrowed the design right. The rule also prohibits showing alternate positions of design components with full and broken lines in the same view.

Nothing in the EU system requires surface shading in the same way. Representation requirements there are about disclosing the appearance clearly and consistently across the views filed. The consequence for a dual-filing programme is that the US set is the constraining one: build the US-compliant set first, with shading and a deliberate solid/broken line strategy, and the EU set can be derived from it. Deriving in the other direction almost always means redrawing. Our guide to design patent drawings goes through the view set in detail.

Building One Drawing Set That Survives USPTO vs EPO Patent Drawings Review

The economics favour a single master set drafted to the strictest applicable standard, then relaxed per jurisdiction. Working the other way — drafting for the US and adapting for Europe — is what produces two incompatible sets and a redrawing bill at every national phase entry.

A sequencing that holds up for a programme filing in both regions:

1. Draft on A4, so no European filing needs a conversion step.
2. Apply the 37 CFR 1.84(g) asymmetric margins as the minimum on every sheet.
3. Execute in solid black line work that reads correctly with no colour at all.
4. Keep reference characters at 0.32 cm or above and clear of hatching and leading lines.
5. Strip descriptive text from the figures; carry the wording in the description, with reference numerals in the boxes.
6. Number views as “FIG. 1”, “FIG. 2” in consecutive Arabic numerals.
7. Reconcile every reference sign against the brief description of the drawings before filing.
8. Add colour or greyscale only as a jurisdiction-specific overlay — never as the layer that carries the disclosure.

Two checks are worth building into the docket rather than leaving to the draftsperson. Before any international filing, confirm the figures are compliant in black and white under Rule 11.13(a), because that is the standard that locks in. And before any US design filing, confirm the surface shading and the solid-versus-broken line strategy against 37 CFR 1.152, because that is the one that silently changes scope.

A full USPTO vs EPO patent drawings review on an existing portfolio usually turns up the same three findings: stale Rule 46 EPC references in internal standards, Letter-sized masters that clip the bottom margin on A4 conversion, and flowcharts carrying sentences that would not survive Rule 11.11. None of the three is expensive to fix before filing. All three are expensive afterwards. Our walkthrough of our walkthrough of 37 CFR 1.84 is the companion piece on the US half of this.

Get One Drawing Set That Clears Both Offices

We prepare figures to the strictest applicable standard through our patent drawing services — drafted on A4, compliant in black and white under PCT Rule 11.13(a), with colour or greyscale added only where the receiving office accepts it. If you have an existing portfolio whose internal drawing standard still cites Rule 46 EPC, we will audit it against current practice before your next filing. Talk to our team.

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