devcat
September 24, 2026
Getting a patent granted in Singapore isn’t just about claims and novelty. The drawings matter just as much.
The Singapore patent drawing requirements are defined in the Rule 21 of the Patents Rules and the official Formalities Manual issued by IPOS. These are highly specific.
Sheet size, figure numbering, margins, line quality – every detail is regulated. And if you’re assuming that WIPO-compliant PCT drawings will automatically pass through the national phase unchallenged, think again.
Singapore follows international norms where it makes sense. But it enforces national rules where precision matters.
A drawing that slides through in the international phase may still be flagged during national processing in Singapore. This happens if it doesn’t meet local layout, formatting, or content rules.
That’s why we wrote this guide. It explains each requirement clearly, with source-based answers and no legal jargon.
Let’s begin with which types of drawings are acceptable and when they are actually required.
Patent drawings are not always mandatory in Singapore, but when they are included, they must meet specific formal requirements. This section outlines when drawings are required, whether optional drawings are allowed, and how missing drawings are treated under Singapore’s patent rules.
No. Drawings are not always required. However, drawings must be submitted if they are referred to in the description or the claims. If no drawing is referenced in either section, it is not mandatory.
Yes. If the invention can be better understood with a drawing, the applicant may include it, even if the drawing is not technically required. Rule 21(1) allows such optional drawings, provided they comply with all formal requirements.
Yes. If a drawing is referred to in the description or claims but was not submitted, the Registrar may issue a deficiency notice during preliminary examination. The applicant must then file the missing drawing, and may need to file Patents Form 56 along with a request to retain the original filing date.
If the entire sheet of drawings is missing, a later filing date may apply, unless incorporation by reference conditions are met.
Yes. flow sheets and diagrams are considered drawings. However, like other drawings, hey must be submitted as a separate part of the specification, not embedded within the description.
If drawings are filed, the abstract must indicate which figure(s) are to be published. If this is missing, the Registrar may issue a Formalities Examination Adverse Report. The applicant must correct this using Patent Form 13.
Yes, but only under specific conditions. The applicant must file Patents Form 56 within 3 months of the original filing date and meet all five incorporation by reference conditions. Otherwise, the filing date will be updated to the date the drawing was received.
In Singapore, if a drawing referred to in the description is missing, the Registrar will notify the applicant during preliminary examination. The applicant is then required to submit the missing drawing via Patents Form 56 within 3 months from the date of the Registrar’s notification.
To retain the original filing date, the applicant must also meet specific incorporation-by-reference conditions under Section 11.3.5.
No. If the correction is of an obvious mistake, it is not treated as a formal amendment requiring examination of new subject matter. Instead, such corrections may be made under Rule 91, using Form CM4. The applicant must clearly identify the mistake and provide evidence that the correction reflects the original intent.
However, if the correction introduces new information or clarity, it may be treated as an amendment.
Drawings can be amended:
However, amendments must not introduce subject matter that extends beyond the original disclosure.
If a drawing is referenced but missing, the Formalities officer will raise a deficiency during preliminary examination. This is flagged in the Formalities Examination Report. The applicant must respond using Patents Form 13 (to amend) or Form 56 (to submit missing parts). IPOS may allow retention of the original filing date only if the incorporation-by-reference conditions are fully met.
Patent drawings submitted to IPOS must follow strict specifications for sheet size, usable surface, and margins. These rules ensure that all drawings are legible, reproducible, and consistent with official formatting standards.
This section outlines the acceptable sizes and layout boundaries under Singapore’s patent system.
Patent drawings must be submitted on A4-sized sheets (21.0 cm × 29.7 cm). Other sheet sizes are not accepted for formal submission.
While Singapore law does not specify an exact usable surface area in centimeters, drawings must be made within margins that leave a clear area for official use, and the drawing must be clearly distinguishable without overcrowding.
The Formalities Manual also implies that drawings must not occupy the full sheet and must allow space for numbering and processing.
Source – Rule 21
No. Rule 21 does not permit the use of frames around the drawing area. The sheet must be left clear, aside from the actual figure, sheet numbers, and reference signs. Frames are considered unnecessary and may interfere with clarity and legibility.
Margins must be sufficient to allow for reproduction, file processing, and publication.
The IPOS allows the following margins, which are in alignment with PCT and other major jurisdictions:
Singapore’s patent system requires that drawings be placed in a specific part of the specification and formatted consistently.
This section covers where to include drawings in the application, how to structure them, and what format rules apply to ensure compliance with Rule 21 and IPOS guidelines.
Drawings must be placed after the claims and before the abstract. They should be submitted as a separate part of the specification.
Most importantly, the abstract itself must reference the drawing (or up to two figures) intended for publication. If no figure is suitable, the phrase “No Figure” must be indicated. Failing to do so can trigger an adverse report from the Registrar.
Each drawing sheet may contain multiple figures, provided they are arranged in a clear and space-efficient manner. Figures should be numbered consecutively in arabic numerals, and no figure should overlap or interfere with another. If space runs out on one sheet, additional figures must continue on the next sheet.
Moreover, if a figure spans multiple sheets, it must be arranged so the whole figure can be assembled without concealment.
No. Drawing sheets must only contain illustrations and relevant reference signs. Text from the description, claims, or any commentary is not permitted on the drawing sheet. The only text allowed includes figure numbers, brief labels, or reference signs.
Yes. Figures must be sequentially numbered using Arabic numerals (e.g., Fig. 1, Fig. 2, etc.). The numbering must be clear and placed near the corresponding drawing, without overlapping any lines.
Each drawing sheet must be numbered in the center of the top or bottom of the sheet, but not in the margin. This requirement ensures consistency and clear identification of sheets.
Drawing sheets must be numbered consecutively as a separate series, using Arabic numerals. Although the Singapore rules do not explicitly mandate a “2/5” (i.e., sheet X of Y) format, they require clear, consecutive numbering distinct from other document sections.
Textual content in Singapore patent drawings is subject to strict limitations. Only a narrow set of exceptions are permitted, intended solely to aid understanding of the invention. This section details the rules governing when and how such text may be included.
No. Patent drawings must not contain any descriptive text, commentary, or narrative content taken from the description or claims. The only text permitted is brief, indispensable terms required to understand the drawing. Examples include such as water, steam, open, closed, or section on AA.
In the case of electrical schematics, block diagrams, or flow sheets, a few short catchwords may be used, but only if absolutely necessary for clarity.
Permitted words must be placed so they do not interfere with the legibility or reproduction of the drawing. They should be clear, concise, and must allow for replacement without obscuring lines, reference signs, or other drawing elements. This ensures that translation or formatting for publication can be done cleanly.
From line weight to reference sign consistency, PCT Rule 11.13 outlines how patent drawings must be executed to meet international filing standards. These requirements are also reflected in Singapore’s national rules, which governs line quality, scaling, figure layout, and labeling for drawings submitted to IPOS.
Drawings must be executed in durable black ink, with dense, dark, and uniformly thick lines and strokes that are well-defined. However, the use of color is strictly prohibited. This ensures that drawings can be accurately reproduced without degradation.
Cross-sections shall be marked with oblique hatching. The hatching must not interfere with reference signs or leading lines. This technique provides clarity while preserving the readability of identifiers.
Drawings must be clear enough that a photographic reduction to two-thirds still allows every detail to be seen clearly. If a scale is included, it should be represented graphically, not written as text.
If a scale is required, it must be graphically represented. For example, as a bar or line, and not written in numbers or words. This ensures that the scale remains accurate even when the drawing is reduced or enlarged.
All numbers, letters, and reference lines must be simple, clear, and legible. You must not use brackets, circles, or inverted commas with them. This prevents confusion in interpreting the drawing.
Lines must generally be drawn using drafting instruments to ensure clarity and uniformity. Freehand lines are discouraged unless they meet the same standard of precision.
Each element in a figure must be in proper proportion to the others. You may only use disproportionate scaling if it is indispensable for clarity.
The minimum height must be 0.32 cm. Moreover, only Latin letters (and Greek where customary) are permitted.
Yes, but with clear limitations. While PCT Rules permits a file reference in the upper left corner of each sheet of drawings, the Singapore Patents Rules and IPOS guidelines do not explicitly mention this practice for national phase filings.
However, IPOS adheres closely to PCT standards for formatting. Therefore, file references may be included on drawing sheets for international applications, provided:
No. Reference signs must only be used in the drawings if also mentioned in the description, and vice versa. This ensures consistency throughout the application.
Yes. The same reference sign must be used consistently across all drawings for the same feature.
No. Singapore patent drawings must be line-based and rendered in black, white, or grayscale. Photographs are not accepted in place of drawings under normal circumstances.
Singapore’s patent drawing requirements may seem detailed, but meeting them ensures your application stays on track. If you need support, Pinch can transform your sketches into fully compliant patent drawing, fast and flawlessly.
Patent drawings are not just visual aids. They’re legal assets governed by strict formatting rules. In jurisdictions like Singapore, getting even a small detail wrong can delay or derail your application. That’s where Pinch Patent Drawings comes in.
Whether you’re filing under the PCT or directly with IPOS, Pinch helps you meet all Singapore patent drawing requirements without breaking a sweat. Just upload your sketches or CAD files, and we’ll convert them into fully compliant, professionally formatted drawings that adhere to every rule in the book.
And it’s not just Singapore. Pinch supports global compliance with region-specific services for:
So no matter where you’re filing, you get drawings that pass the first time.
Want to avoid drawing-related objections altogether? Start with Pinch. The first use is on the house. No drama. Just clean, compliant drawings on demand.
Try it now and file with confidence.
Disclaimer:
This article is based on official sources, including Rule 21 of the Singapore Patents Rules and the IPOS Manual of Patent Practice and Procedure. Every effort has been made to simplify and interpret the content accurately for patent applicants and service providers.
However, the regulations governing Singapore patent drawing requirements may be updated from time to time. This article reflects the most current information available at the time of publication, but we recommend consulting the Intellectual Property Office of Singapore (IPOS) or a qualified patent professional to ensure compliance with the latest standards before filing.
For every innovator, attorney, and team working to protect ideas and file patents faster. We are the only platform that combines speed, compliance, and confidentiality to simplify your patent drawing process.
For every innovator, attorney, and team working to protect ideas and file patents faster. We are the only platform that combines speed, compliance, and confidentiality to simplify your patent drawing process.
