Poster Size Conversions for International Wheatpaste Campaigns

If you’ve ever managed a US brand campaign that ran internationally, you’ve probably hit the format problem. Your designer built everything to 24×36 inches. The print house in London stocks A1 — 594x841mm. The numbers are close enough that it seems like it should work. It doesn’t. Not exactly. And “close enough” in large-format print production means a crop you didn’t plan for or a reprint you didn’t budget for, discovered the day your campaign needs to be on walls.

The American Guerrilla Marketing team has dealt with this problem firsthand across campaigns in the UK, Western Europe, Japan, Canada, and Australia. We’ve caught it in production before it cost anything. We’ve also, early in our decade of international work, learned it the hard way — when a file built to US specs went to a Berlin print house that produced it to the nearest ISO standard and handed back posters with a 4mm white border on the long edge. Not visible at 10 feet. Extremely visible at 3 feet on a high-traffic wall in Mitte.

This guide is the reference we use internally and share with every client running an international campaign. It covers the conversion table from US imperial to international metric formats, what “close but not identical” actually means for production, the color mode issue that kills campaigns before they’re printed, Japan’s JIS B-series divergence from ISO, Canada’s dual-standard problem, and how to set up a production workflow that keeps your files clean across markets.

The Core Conversion Table: US Imperial to International Metric

Before getting into the nuances, here’s the base reference. These are the most common US large-format sizes used in wheatpaste campaigns, their closest international metric equivalents, and the actual dimensional difference between them.

A few things to note about this table before we go further. First, it shows that the US 48×72 and the European 6-Sheet (1200x1800mm) are actually very close on the long edge — the difference is mainly in the short dimension. This is one of the cleaner conversions. Second, the 27×40 US One-Sheet has two different UK equivalents: the ISO B1 and a UK-specific one-sheet standard at 686x1016mm. The UK has historically used its own one-sheet standard that doesn’t map to ISO. Know which one your UK print vendor stocks before you send files. Third, the gap between US 24×36 and ISO A1 is not trivial. More on this below.

What “Close but Not Identical” Actually Means in Production

When designers see that US 24×36 is close to ISO A1, the natural instinct is to assume you can scale one to the other without consequence. That instinct is wrong for a specific reason: the proportions are different, not just the dimensions.

US 24×36 has an aspect ratio of 1:1.5. ISO A1 has an aspect ratio of 1:1.414 (the square root of 2 — this is how all ISO A-series sizes work; each size is exactly half of the next larger one, folded on the long axis). These are not the same ratio. A simple scale-to-fit will introduce either cropping or white space depending on which direction you scale.

Here’s what this means practically. If you take a 24×36 file and scale it to fit within the A1 width (594mm), the height of the scaled file will be 841.5mm — essentially perfect. But the proportions only work in this direction because you’re lucky with these specific dimensions. Go the other direction (scale to fit the A1 height of 841mm) and the width comes out to 560.7mm, leaving a 33mm white strip on one edge.

For a poster with edge-to-edge imagery, any crop changes the composition. For a poster with a centered design and clear margins, a small crop may be invisible. The key question is: which edge takes the hit, and has the designer seen and approved that change before print production starts? Most print production problems in international wheatpaste campaigns happen because nobody asked this question explicitly. The agency assumed the resize was clean. The designer didn’t know a resize happened. The poster comes back different from the approved proof and nobody knows exactly why.

The cleaner solution: when you know a campaign is running internationally, set up the master file at ISO A1 dimensions from the start if A1 is the primary production format. If the campaign is genuinely multi-market with different format requirements in each region, build a production master at the largest required size and export market-specific crops with explicit sign-off from the designer and client on each one.

The UK One-Sheet Situation

The UK has its own historical poster standard that predates ISO adoption. The UK one-sheet is 686x1016mm — close to 27×40 inches (685.8x1016mm) but not identical to ISO B1 (707x1000mm). UK cinema and entertainment print vendors, in particular, often stock the 686x1016mm format because it’s what the UK film industry has used for decades.

If you’re running a campaign in London and your US size is 27×40, confirm which format your UK print vendor stocks before you send any files. The answer determines your production spec. The practical consequence of getting this wrong: your posters arrive 21mm too narrow or 16mm too tall depending on which way the vendor adjusts, and the crop falls in an unpredictable place unless you’ve planned for it.

When we’ve walked campaigns through London print production — Shoreditch, Brixton, Camden — we confirm the vendor format standard before every production run. It’s a five-minute call that eliminates the possibility of a format-driven reprint.

The Color Mode Problem: Why Your Files Look Right and Print Wrong

This is the issue that trips up US brands more consistently than any size conversion problem. Most design work in the US is produced in RGB color mode because most of the primary use cases for design files are digital: websites, social media, presentations, video. RGB is the native color space for screens. Files built in RGB look exactly right on every monitor you review them on.

Professional print production — everywhere, not just internationally — requires CMYK. CMYK (Cyan, Magenta, Yellow, Key/Black) is the color model for ink-on-paper. When an RGB file gets sent to a print vendor and they convert it to CMYK for the press, the conversion is not one-to-one. Colors shift. The specific shifts depend on which CMYK profile is used, but some patterns are consistent:

• Saturated reds often print orange in CMYK if the RGB values were built around screen-vibrant red values
• Screen blues can flatten significantly — what looked like a deep electric blue on screen becomes a muddier blue-gray in print
• RGB blacks built as R:0 G:0 B:0 often print as a cool gray in CMYK, not a rich black. Rich black in print requires a mix of all four channels
• Neon and fluorescent tones that are achievable in RGB are simply not achievable in standard CMYK. These require specialty inks that most large-format print vendors don’t stock

The reason this matters for international campaigns specifically: you’re not there to catch it. When your campaign runs domestically, your field contact can pull a print proof, call you, and you can make a correction before the run starts. When the print run is happening in Berlin or Osaka while you’re in New York, you’re relying on the agency and the print vendor to catch a color issue you didn’t prevent on the front end.

The prevention is straightforward: build files in CMYK from the start, or convert to CMYK and review the converted file before it goes to any print vendor. The review matters because you need to see the converted file, not just know that a conversion happened. Many design tools will show you a CMYK preview before exporting. Use it. If the preview shows color shifts that affect your creative, adjust the colors in CMYK space until the print preview looks right, then export the CMYK file as your production master.

Resolution Requirements for Large-Format Print

While we’re in production specs: large-format print for wheatpasting is typically produced at 150-300ppi depending on viewing distance and the vendor’s equipment. The general rule is that large-format pieces viewed at a distance can use lower resolution because the eye integrates the detail from farther away. A 24×36 poster designed for close viewing at eye level needs 300ppi. A 6-sheet placement designed to be read from across the street can be produced at 150ppi without visible quality loss.

For any format you’re sending to an international vendor for the first time, confirm their preferred resolution before building or exporting files. Some high-end European print vendors run equipment that performs best at specific resolutions. Sending a file at a resolution their press doesn’t match means a resampling step that can introduce artifacts.

Japan’s JIS B-Series: Why It’s Different from ISO B

Japan uses JIS (Japanese Industrial Standards) for paper sizes alongside ISO. For A-series sizes, JIS and ISO are identical — JIS A1 is the same as ISO A1. The divergence happens in the B-series, and it matters for production.

ISO B1 is 707x1000mm. JIS B1 is 728x1030mm. That’s 21mm wider and 30mm taller — approximately 3% larger in each dimension. The difference is not visible at a glance when you’re looking at a blank sheet of paper. It is visible when you print an ISO B1 file on JIS B1 stock, because the image will have a 10.5mm white border on each long edge and a 15mm white border on each short edge.

This matters because Japan’s print industry predominantly uses JIS B-series for large-format work. If you send ISO B1 files to a Tokyo print house without specifying, many vendors will print them on JIS B1 stock, because that’s what they have. The border problem is predictable and entirely preventable — but only if you know to brief your designer to JIS B1 dimensions before the file is built.

The practical consequence for international wheatpaste: if your campaign is running in Tokyo — Shibuya, Shimokitazawa, Harajuku, Nakameguro — and your US file is 27×40 (ISO B1 equivalent), your production spec for Japan needs to be JIS B1 (728x1030mm), not ISO B1. These look like the same request to someone who doesn’t know the JIS divergence exists. The brief needs to be explicit.

For campaigns that span both ISO-standard markets (UK, Germany, France, Australia) and Japan simultaneously, the cleanest approach is to build two production masters: one at ISO B1 for ISO markets, one at JIS B1 for Japan. They’re similar enough that a designer who has already built the ISO version can adapt to JIS in under an hour. The alternative — discovering the border problem after the Tokyo print run is complete — is not worth the hour you saved on the front end.

Canada’s Dual-Standard Problem

Canada presents a specific challenge that catches US brands because it looks like the same market. It’s not. Canada has a bilingual, bicultural production environment, and the format standards reflect that divide.

English Canada largely follows US imperial standards. A print house in Toronto or Vancouver will understand 24×36, 27×40, and 18×24 without explanation. Most of their large-format equipment is calibrated for these dimensions because the US supply chain drives the industry in English-speaking markets. For campaigns running in Toronto or Vancouver, your US files will generally work without conversion.

Quebec — Montreal specifically — is different. Quebec’s print industry aligns more closely with French and European metric standards. A Montreal print house is more likely to stock ISO A1 and B1 than US imperial equivalents. They may technically accept US dimensions, but they’re converting them to metric in their workflow, which reintroduces the proportion problem described above.

Before briefing any Canadian print vendor, confirm two things: what standard they stock, and whether their large-format equipment handles the conversion natively or requires you to provide files in their native dimension. A quick call before the brief saves a reprint after the fact. We’ve walked enough campaigns through Montreal to know that assuming English Canada norms apply throughout Canada is the mistake that creates problems.

For campaigns covering both Toronto and Montreal in the same run, the cleanest solution is either to brief to metric (ISO A1 or B1) as the production master and confirm the Toronto vendor is comfortable with it, or to produce two separate files and track them clearly through the production and delivery chain. The latter requires airtight file naming.

Setting Up a Production Master File for Multi-Market Campaigns

For campaigns running in multiple international markets simultaneously, the production master file approach prevents the variant explosion that happens when each market gets its own version of the design with its own revision history. The goal is one source file with market-specific exports, not five different versions of the file floating across five different shared drives.

Here’s how we approach it for campaigns with multiple international markets:

Step 1: Identify the largest required format across all markets. If the campaign is running A1 in the UK, B1 in Germany, and JIS B1 in Japan, the largest format is JIS B1 (728x1030mm). Build the production master at this size in CMYK at 300ppi.

Step 2: Design within safe zones that work across all target formats. Place critical design elements (headline, logo, key imagery) within the area that will survive all format exports without being cropped. Mark the safe zone as a non-printing guide layer in the source file.

Step 3: Create market-specific export presets. In your design application, set up named export presets for each market’s format: UK_A1_CMYK_300ppi, DE_B1_CMYK_300ppi, JP_JIS-B1_CMYK_300ppi. This way, any version update to the source file can be re-exported to all markets in a consistent workflow.

Step 4: Route market-specific exports to market-specific print vendors with confirmed specs. Do not send a batch of files to multiple vendors and let them sort out which one is theirs. Each vendor gets their specific file and nothing else.

Step 5: Maintain version control on the source file only. If the client approves a copy change after initial files have been distributed, update the source file and re-export all market variants from the updated source. Don’t edit individual market exports manually — that’s how you end up with Germany running version 2 and Japan running version 1 on the same campaign.

File Naming Conventions That Prevent Market Mix-Ups

On a multi-market production run, a file named “final_poster_v3.pdf” is a liability. It tells the print vendor nothing about which market it’s for, what size it is, whether it’s in the right color mode, or what version it represents. When you’re coordinating production across three or four international markets, ambiguous file names cause misprints, and misprints cause reprints, and reprints cause delays.

The file naming convention we use for international wheatpaste campaigns follows this structure:

[CampaignCode]_[Format]_[ColorMode]_[Resolution]_[Version]_[Market].pdf

An example from a real production workflow: StreamingLaunch_A1_CMYK_300ppi_v3_UK.pdf

Break that down:

• StreamingLaunch — campaign identifier, not the brand name (keeps files generic enough to share with vendors without revealing client relationships)
• A1 — the exact output format, no ambiguity
• CMYK — confirms color mode so the vendor doesn’t need to check
• 300ppi — confirms resolution so the vendor knows the file is production-ready
• v3 — version number, so everyone knows this isn’t the original
• UK — market identifier, so this file never accidentally ends up in the German print queue

Compare this to final_poster_v3.pdf. That filename answers none of those questions. On a single-market campaign, it’s fine. On a multi-market run with production happening simultaneously in three countries, it’s a problem waiting to surface.

The naming convention is worth documenting in your campaign brief and enforcing when you receive deliverables from your design team. Files that arrive without market-specific naming get renamed before they go anywhere near a print vendor.

Pre-Production Checklist: What to Confirm Before Sending Files to Print

Before any file leaves for international production, run through this checklist for each market. It takes about 10 minutes per market and prevents the problems that take days to fix.

Summary: The Format Rules That Matter Most

A decade of boots on the ground in international markets has taught us that production problems in international wheatpaste almost always trace back to one of three things: wrong format spec, wrong color mode, or no one confirmed either before the run started. Here’s the short version:

• US 24×36 and ISO A1 are not the same proportions. Build to the actual production format or explicitly approve the crop.
• 27×40 has two different UK equivalents. Know which one your vendor stocks.
• ISO B1 and JIS B1 are not the same. Japan uses JIS. Brief your designer to JIS dimensions if the campaign runs in Tokyo.
• RGB files print differently than they look on screen. Convert to CMYK and review the converted file before it goes to print.
• Canada’s English-French divide extends to format standards. Confirm with every Canadian vendor before briefing.
• Build one production master per campaign, export market-specific files from that master, name files with market and format in the filename.
• Run the pre-production checklist for every market before any file goes to print.

These aren’t abstract rules. They’re the specific lessons from real production runs in real international markets. The ones we learned the hard way, years ago, we now catch in the pre-production checklist before they can affect a client campaign.

Frequently Asked Questions

Can I just resize a US 24×36 poster file to A1 for international printing?

Not cleanly. US 24×36 inches (609.6×914.4mm) and ISO A1 (594x841mm) are close but not the same proportions. A simple resize will either crop your artwork or introduce white borders. You need to either redesign the layout to fit A1 proportions or explicitly decide which edge to sacrifice and confirm that with your designer before sending files to print.

What color mode should international wheatpaste files be submitted in?

CMYK, 300ppi minimum. US design files are often built in RGB because they were originally intended for screen presentations or digital use. RGB files look correct on a monitor but shift when converted to CMYK for print — reds often go orange, blues can flatten, and saturated blacks can appear gray. Send CMYK files to every printer, every market, every time.

What is the difference between ISO B1 and JIS B1?

ISO B1 is 707x1000mm. Japan’s JIS B1 is 728x1030mm — approximately 3% larger in each dimension. The difference sounds small but it matters for production: files built to ISO B1 spec will have visible white borders when printed at JIS B1. Brief your designer on JIS dimensions specifically if the campaign is running in Japan.

Does Canada use metric or imperial poster sizes?

Both, depending on the region and the print vendor. English Canada typically follows US imperial standards, so 24×36 and 27×40 are understood. Quebec and many Montreal print houses lean metric and may default to ISO A1 or B1. Before briefing any Canadian print vendor, confirm which standard they stock and whether their large-format equipment is calibrated for imperial or metric dimensions.

How should I name files for a multi-market international wheatpaste campaign?

Include market, size, color mode, resolution, and version in the filename. A convention like Campaign_A1_CMYK_300ppi_v3_UK.pdf is unambiguous at a glance. Compare that to final_poster_v3.pdf, which tells the printer nothing about which market the file belongs to or whether it’s been converted to CMYK. On a multi-market production run, poor file naming causes misprints and market mix-ups.