You’re scrolling through Louis Vuitton’s website or walking past a boutique window, and you see two almost identical bags: one labeled “Neverfull MM” and another “Neverfull PM.” Suddenly, your shopping excitement turns to mild panic. What do those two little letters mean? Are they sizes? Styles? Secret codes for VIP customers? If you’ve ever felt this confusion, you’re not alone. The terms “MM” and “PM” are among the most common—and misunderstood—abbreviations in the Louis Vuitton universe. Let’s demystify them together, so your next purchase feels confident, not cryptic.

The Simple Truth: MM and PM Are Size Codes

At their core, MM and PM are simply size indicators. They come from French, the language of Louis Vuitton’s headquarters. PM stands for “Petite Modèle,” which translates to “small model.” MM stands for “Moyen Modèle,” meaning “medium model.” So when you see a Speedy PM, you’re looking at the smaller version of that classic bag. The Speedy MM is the medium version. It’s that straightforward. There’s no GM (Grand Modèle, or large model) and sometimes even a mini or nano size, but PM and MM are the two you’ll encounter most often in the middle of the size spectrum.

Why French? Louis Vuitton was founded in Paris in 1854, and the brand has kept many of its original naming conventions. It’s a nod to heritage, but for non-French speakers, it can feel like a puzzle. Think of it this way: just as “S,” “M,” and “L” on a t-shirt tell you the fit, PM, MM, and GM tell you the bag’s proportions. The key difference is that these codes are specific to each bag model, not a universal sizing chart. A PM in one line might be bigger than a PM in another, so always check dimensions.

How to Read the Codes Across Different Collections

Louis Vuitton uses these abbreviations consistently, but their meaning changes depending on the bag’s design. For example, the iconic Speedy bag comes in several sizes: Speedy 25 (often labeled as PM), Speedy 30 (MM), and Speedy 35 (GM). Here, PM corresponds to a 25-centimeter width, MM to 30 cm, and GM to 35 cm. But take the Neverfull tote: its PM measures about 11.4 inches wide, while the MM is 12.6 inches, and the GM is 14.2 inches. Notice how the MM in Neverfull is actually smaller than the GM in Speedy? That’s because each model has its own proportion logic.

This is where many shoppers get tripped up. You might assume an MM is always a medium size, but in reality, it’s medium for that specific bag. A Neverfull MM is a generous everyday tote, while a Speedy MM is a compact handbag. The best approach is to ignore the letters and focus on the actual measurements. Louis Vuitton lists dimensions in centimeters on its product pages. If you’re shopping secondhand, check the model number or ask the seller for the exact width, height, and depth.

Here’s a quick cheat sheet for popular models:

• Speedy PM: Usually 25 cm wide, fits daily essentials like a wallet, phone, and keys.
• Speedy MM: Usually 30 cm wide, room for a small tablet or a light scarf.
• Neverfull PM: 11.4 inches wide, ideal as a chic lunch bag or minimalist work tote.
• Neverfull MM: 12.6 inches wide, the most popular size for work and travel.
• Alma PM: 12.6 inches wide, a structured bag that fits an iPad mini.
• Alma BB: Note this one—BB stands for “Baby” or smaller, not PM.

Why Knowing MM and PM Matters for Your Wallet

Size isn’t just about capacity—it directly affects price. In almost every Louis Vuitton line, larger bags cost more. A Neverfull PM might retail for around $1,500, while the MM jumps to about $1,700, and the GM to $1,900. That $200 difference might not seem huge, but it adds up if you’re buying multiple pieces. More importantly, resale value varies by size. Smaller, limited-edition sizes (like the Speedy 20, which is even smaller than PM) often appreciate faster because they’re rarer. Meanwhile, MM sizes tend to hold steady value since they’re the most practical for everyday use.

Another practical consideration: weight. A larger bag means more leather, canvas, and hardware. The Neverfull GM, for instance, is noticeably heavier than the PM, even when empty. If you’re prone to shoulder strain or plan to carry the bag for long periods, the PM or MM might be smarter choices. Also, consider your frame. A petite person might find a GM tote overwhelming, while a taller individual might find a PM bag too dainty. The letters help you visualize proportion, but nothing beats trying the bag on in person or measuring against a bag you already own.

Beyond PM and MM: Other Size Codes You’ll Encounter

Louis Vuitton’s size system extends beyond PM and MM. You’ll also see:

• GM (Grand Modèle): Large model, the biggest standard size for most bags.
• BB (Baby): Smaller than PM, often used for crossbody bags like the Alma BB or Palm Springs BB.
• Nano: Ultra-mini, barely big enough for a phone and cardholder.
• XXL: Extra-extra large, usually for travel bags or limited editions.
• PM+ or MM+: Occasionally used for extended versions with more depth or compartments.

These codes aren’t always printed on the bag itself. Instead, they’re part of the product name on the price tag or website. If you’re buying pre-owned, the date code (a series of letters and numbers inside the bag) can help you verify the model and size. But for most shoppers, a quick glance at the dimensions is more reliable than memorizing every abbreviation.

Practical Tips for Choosing Between PM and MM

Now that you know the basics, here’s how to apply them to your next purchase. Start by listing what you carry daily. If it’s just a phone, card case, lip balm, and keys, a PM is likely perfect. It keeps you organized without excess weight. If you need to add a small water bottle, sunglasses case, or a paperback, move up to MM. For work commuters or parents, the GM might be necessary, but remember that a bag can always be less full—you can’t shrink a too-large bag.

Think about your lifestyle. Do you attend events where a smaller bag feels more elegant? The PM is your evening companion. Are you a traveler who needs a carry-all for flights? The MM or GM fits a laptop and magazines. Also, consider the bag’s closure. A Speedy PM with a zipper is secure for crowded subways, while an open Neverfull PM might feel less safe. The size affects how the bag carries—larger totes can sag or lose shape if underfilled.

Finally, don’t let the letters intimidate you. Louis Vuitton sales associates are trained to help you compare sizes. If you’re shopping online, use the “compare” feature or look for videos that show the bag on a model. Remember that PM and MM are just starting points. The best size is the one that fits your life, not the one that sounds most impressive. And if you ever forget, just think: PM for “petite” (small), MM for “medium.” You’ve got this.