Patent drawing software compared: free and AI
Short answer: for software or method flowcharts and system block diagrams, a free tool such as draw.io works if you do the 37 CFR 1.84 checks yourself, and an AI generator with an editor is faster. For mechanical, electrical or design drawings, hire a draftsperson. Below: Visio, PowerPoint, Lucidchart, draw.io, an AI tool, outsourcing and PatentQuill, with prices read from each public page on 2026-11-11.
5 free credits — about 1–2 complete drawings · no card
The tools side by side
Prices are as shown on each vendor’s own page, checked 2026-11-11; plans change, so open the link. Where a page did not show a price we say so rather than guess. For per-sheet prices from draftspeople see how much patent drawings cost.
| Method | Price (source, checked 2026-11-11) | Suits | Strength | Limit |
|---|---|---|---|---|
| Microsoft Visio | Plan 1 $5, Plan 2 $15 per user per month, paid yearly. microsoft.com/visio | Flowcharts, block diagrams, schematic-style layouts | Mature shape libraries; precise alignment. | No patent-sheet rules built in: line colour, letter height, margins, FIG. labels are set and checked by you. |
| Microsoft PowerPoint | Pricing not read from the official page on this date; it is sold with Microsoft 365. microsoft.com/powerpoint | Simple boxes and arrows | Already installed for many people. | Slide-sized page; default fills, shadows and fonts must be removed by hand to get black line art. |
| Lucidchart | Free, Individual and Team plans exist; the page text we could read did not show prices (pricing not published in our read). lucid.app/pricing | Flowcharts and block diagrams | Browser-based; easy sharing. | General diagramming product; the patent sheet format is yours to set and check. |
| draw.io (diagrams.net) | Free. The site says “Free forever • No sign-up required”. drawio.com | Flowcharts and block diagrams | No cost, exports SVG and PDF. | Same as other general tools: formal checks and numeral matching are manual. |
| PatentFig AI (AI patent drawing tool) | Free $0 (30 credits on sign-up day, then 10 a day); Basic $20, Pro $40, Enterprise $80 per month as shown, about 50, 150 and 400 figures. patentfig.ai | Figures from text, sketches or photos, incl. line art, 3D and flowcharts; lists several patent offices | Broader figure range than a flowchart-only tool; many offices listed. | Credit-based; every generated figure still has to be read against your claims. |
| Outsourced patent draftsperson | Published utility prices from $15 to $150 per sheet across six services. six sources on the cost page | Mechanical, electrical, design and complex figures | A person handles geometry, views and shading; the right route for parts drawings. | Per-sheet pricing; each revision round takes time; rush fees are rarely published. |
| PatentQuill | 5 free credits on Google sign-in; yearly plans from $0.33 a drawing, credit packs $0.67–$1.00. Editing is free. pricing | Method flowcharts and system block diagrams only | Boxes use your own wording; sheet checked against 37 CFR 1.84; numeral cross-check. | No mechanical, electrical or design drawings; US utility sheets only. |
Other AI patent-drawing tools exist; the checker tools comparison covers the ones we could open. Third-party tools are described only from their public pages.
How each route works
Which method fits your figure
The choice follows the figure, not the brand. A text-to-diagram tool is quick for boxes and arrows and has nothing to offer for a bracket or a sectional view.
- Software or method flowcharts, system block diagrams
- A generator plus an editor. Paste the description and get boxes labelled with your own wording, then fix any box by clicking it. PatentQuill does this for method steps and system modules, and checks the sheet against 37 CFR 1.84 before export. See patent flowcharts, and patent block diagrams.
- Mechanical, structural, electrical or design (ornamental) drawings
- A professional patent draftsperson, or CAD. These figures need part geometry, section views and shading conventions that a text-to-diagram tool cannot produce. PatentQuill does not draw them; use a draftsperson or a CAD program you know well.
- A near-zero budget and only one or two simple figures
- A general drawing tool and your own 37 CFR 1.84 checklist. Free or cheap, but every formal point is yours: solid black lines, letter height, margins, “FIG.” labels and sheet numbers. Work through the rule list, then measure the finished sheet with the free checker. See 37 CFR 1.84 requirements, and patent drawing checker.
- A hand-drawn sketch on paper
- Scan it, convert it to clean black line art, then check the sheet. Scan at filing resolution, remove pencil shading and any color so the lines are solid black on white (37 CFR 1.84(a)), place the figure inside the margins, and add the “FIG.” label and sheet number before checking. See sheet requirements.
A drawing tool should do these 6 things
These are the points 37 CFR 1.84 sets on the printed sheet. A drawing that fails them is a redraw, whichever tool made it.
- Black solid lines on white
Lines, arrows and lettering should be solid black at an even weight, with no color, gray fill or transparency so the sheet reproduces cleanly.
PatentQuill: The compliance check reads the finished sheet back and flags any fill, stroke or text that is not black, any transparency, and any image or gradient. A sheet passes only when every one of those measurable checks passes.
- Lettering at least 0.32 cm high
Letters and numerals on the final sheet have to reach the minimum, not just the labels in the source document. We measure capital letters.
PatentQuill: The sheet starts above the minimum and the check measures the real text size on the exported sheet. A tight fit is handled by spacing, wider boxes or scaling that keeps the 0.32 cm letter height; the drawing is not reduced below it silently.
- Margins that nothing crosses
The drawing and its labels sit inside a fixed border; see 1.84(g).
PatentQuill: The layout reserves the margins plus a small safety allowance, and the check reports any element that crosses the printable area on any side.
- A “FIG.” label for every view and a sheet number
Each figure carries “FIG. 1”, “FIG. 2” and so on, and each sheet is numbered “1/2”, “2/2” in the middle of the top.
PatentQuill: Both are drawn automatically and checked on the sheet: a missing figure label or a sheet number that is absent or not centred at the top is reported.
- Reference numerals that match the description
A numeral on the drawing has to name the same part as the numeral in the description, appear once, and appear on both sides.
PatentQuill: Every box is tied to the sentence it came from, and the cross-check lists numerals found in only one place, used twice, or used for two different names. Paid exports include the numeral report.
- Output you can edit
A drawing that cannot be corrected without redrawing costs another round with a draftsperson.
PatentQuill: Click a box to change its words, numeral or position; only that box moves. Export US Letter or A4 PDF sheets, SVG, or 300 dpi PNG. Editing never uses a credit.
37 CFR 1.84(a)(1)
37 CFR 1.84(p)(3) — 0.32 cm, our measure is capital letters
37 CFR 1.84(g) — 2.5 cm top and left, 1.5 cm right, 1 cm bottom
37 CFR 1.84(u) and 1.84(t)
37 CFR 1.84(p), (q)
Practical requirement
The automatic checks cover what can be measured on the sheet. Whether a figure shows every claimed step or element remains the filer’s judgment.
What PatentQuill does not do
Being clear about the boundary is part of choosing a tool. If your drawing is on the wrong side of it, the honest answer is another method.
- Mechanical, structural, electrical schematic and design (ornamental) drawings. PatentQuill draws flowcharts and block diagrams, not part geometry.
- Formats for other patent offices, such as PCT, EPO or UK filings. The sheet layout here follows 37 CFR 1.84 for US utility applications.
- Writing or editing the specification and claims. The drawing is built only from text you supply.
- A guarantee that the USPTO will accept a sheet. Formal requirements can be measured and checked; whether the figures show everything the application needs is your judgment.
What it costs
Free
5 free credits when you sign in with Google, with the full editor and the numeral check. Free exports carry a watermark.
Paid
Yearly plans put a drawing at $0.33. Credit packs cost $0.67–$1.00 a drawing and never expire. Editing is always free.
For reference, six draftsperson services publish $15–$150 per utility sheet (checked 2026-11-11). See patent drawing cost and pricing. A PatentQuill credit is one figure and a sheet can hold several, so the two are not like for like.
Questions
Is there free patent drawing software?
Yes, in two forms. draw.io (diagrams.net) is free and states “Free forever • No sign-up required” on its site. PatentQuill gives 5 free credits when you sign in with Google, with the full editor and the numeral check; free exports carry a watermark. General-purpose drawing tools are free or inexpensive, but you do the 37 CFR 1.84 checks yourself. The free checker measures margins, black lines, letter height, “FIG.” labels and sheet numbers on the finished sheet.
Can AI-generated patent drawings be used?
As a draft, yes. The measurable points — black lines, letter height, margins, figure labels, sheet numbers, numeral consistency — can be checked on the sheet. Whether each figure shows what the description and claims require is a judgment you make by reviewing it against your text. No tool can promise that the office will accept a sheet.
Do I need a patent draftsperson?
Not for flowcharts and block diagrams of software, methods and systems, which can be laid out and checked from your own text. For mechanical, structural, electrical or design drawings, a professional draftsperson or CAD is the realistic route, and some firms require one regardless of the tool.
What figures can PatentQuill draw?
Method flowcharts, with steps numbered S100, S102… or in a 100-style series, and system block diagrams, with modules numbered 100, 102… and numerals on lead lines. Both are for US utility applications on US Letter or A4, exported as PDF sheets, SVG or 300 dpi PNG. It does not draw mechanical parts or design patents.
Is my text kept private?
Your text and drawings are stored in your account and used only to generate and save your drawings. They are not used to train AI models. Our staff do not view your project content unless you authorize it, for example for a support request. Drawings stay until you delete them, and account data is deleted within 30 days of a deletion request. The privacy policy lists the providers that handle your data and what each one receives.
PatentQuill does not provide legal advice. Check the current text of 37 CFR 1.84 and USPTO guidance, or ask your attorney, before filing. Privacy details are in the privacy policy.
Draw the figure you need
Paste a method or system description and export a first sheet. 5 free credits when you sign in with Google.