Swimwear is the single hardest category of clothing to buy online correctly. Unlike other apparel where a fit that's slightly off can be tolerated, a swimsuit that doesn't fit properly ruins the entire experience of wearing it. Monday Swimwear has built a genuine reputation for solving this problem better than most brands, particularly for women who've struggled with generic sizing that never quite works. But the brand also uses a distinctive sizing system that trips up first-time buyers if they don't understand it. That's exactly why a proper Monday Swimwear size guide matters more than for typical retailers, and why doing your research before you order genuinely pays off.
This guide walks through Monday Swimwear's unique sizing system, fabric-specific fit tips that most competing content skips, how to measure yourself accurately, and the honest reality of how the brand fits real bodies. You can also check our own Monday Swimwear coupons code for verified discounts, since premium swimwear becomes meaningfully more affordable when timed around real sale windows.
Why Monday Swimwear's Sizing System Is Different
Before diving into the specific measurements, it helps to understand what makes Monday Swimwear's sizing genuinely distinct from generic swimwear brands.
Monday Swimwear was founded by Natasha Oakley and Devin Brugman, two women who built the brand around the observation that most swimwear was designed by people who didn't wear it. The result is a fit philosophy that fits cup sizes AA through G and body sizes 00 through 16, which is a genuinely wider range than most competitors. The bottoms use standard XS through XXL sizing, but the tops use a distinctive alpha system.
The P-VVV Alpha Sizing System (Explained)
Instead of standard XS/S/M/L/XL/XXL sizing for tops, Monday Swimwear uses:
P = Petite
S = Small
M = Medium
L = Large
V = Voluptuous (what would be XL at other brands)
VV = Very Voluptuous (what would be XXL)
VVV = Very, Very Voluptuous (what would be XXXL)
This alpha system exists specifically because Monday's tops accommodate a broader range of cup sizes for a given band size. Rather than trying to squeeze different cup sizes into standard XL or XXL labels, the V/VV/VVV designations represent genuinely different fits designed for fuller bust configurations.
The important insight for first-time buyers: if you have a fuller bust (D cup and up), you likely need one of the V-series sizes even if you'd typically wear an M or L at other brands. This is the sizing decision that trips up the most first-time customers.
How to Measure Yourself Correctly for Monday Swimwear
Getting accurate measurements before ordering is the single most important step for finding the right size. You'll need a soft measuring tape (or a piece of string measured against a ruler).
Bust Measurement
Wrap the measuring tape around the fullest part of your bust while wearing a well-fitting bra (not a sports bra, which compresses). Keep the tape parallel to the floor and don't pull too tight. Record this number.
Underbust (Band) Measurement
Wrap the tape directly under your bust, where the underwire of a bra would sit. This measurement plus your bust measurement determines your cup size (typically bust minus underbust equals cup size in inches, where 1 inch = A cup, 2 inches = B cup, and so on up to 7 inches = G cup).
Waist Measurement
Wrap the tape around the narrowest part of your waist, typically an inch or two above your belly button.
Hip Measurement
Wrap the tape around the fullest part of your hips, typically at the widest point of your buttocks.
Once you have these four measurements, cross-reference them against Monday Swimwear's official size chart on their fit guide page.
Fabric-Specific Fit Tips (This Is Where Most Buyers Get It Wrong)
One of the most underreported aspects of Monday Swimwear sizing is that the brand's own official guidance recommends different sizing depending on the specific fabric. Miss this and you can order the "right" size for your measurements but still end up with the wrong fit.
Underwire Tops
Size down. The brand's own guidance recommends sizing down in underwire tops because the underwire structure provides support that compensates for the smaller band size.
Crinkle Fabric
Size down if you're between sizes. Crinkle fabric has some stretch and give, so a slightly smaller size will typically fit more securely without becoming uncomfortable.
Chevron Fabric
Size up if you're between sizes. Chevron fabric runs tighter than other Monday fabrics, so choosing the larger of two possible sizes typically produces a better fit.
Ribbed and Textured Fabrics
Follow the standard size chart. Ribbed textures are more forgiving than chevron but less stretchy than crinkle.
The Runs Small Warning
Monday Swimwear specifically labels certain products as "Runs small. We recommend to size up for a comfortable fit." Watch for these warnings on individual product pages before ordering, since they override the general fit guidance.
Fit Recommendations by Body Type and Concern
Based on real customer reviews and independent testing from a variety of body types:
Small to Medium Bust (AA-C Cup)
Standard alpha sizing (P through L) generally works. Choose based on your band measurement rather than cup size, and follow the fabric-specific tips above. Bandeau, triangle, and skimpy triangle styles are your best options for maximum style flexibility.
Larger Bust (D through G Cup)
This is where Monday Swimwear really differentiates itself from generic brands. The V-series sizing (V, VV, VVV) is specifically designed for fuller busts, and independent large-bust reviewers (bloggers testing DDD through G cup sizing) consistently rate Monday Swimwear as one of the best brands for larger bust support. Focus on styles specifically designed for larger cups: underwire tops, thicker straps, and styles with more coverage typically provide better support.
Larger Body Types (Size 12+)
Monday Swimwear's sizing extends through size 16, which is more inclusive than many competitors. The V-series alpha sizing accommodates both larger busts and larger body types with more consistent fit. Independent reviewers at size 12+ consistently report positive fit experiences.
Petite Frame
The P (Petite) sizing is genuinely designed for smaller frames, not just as a smaller version of Small. If you're consistently overwhelmed by standard sizing at other brands, the P size is worth trying first.
Common Monday Swimwear Sizing Mistakes to Avoid
Ordering based on your typical retail size without measuring. Monday's sizing genuinely differs from generic swimwear brands. Measure yourself before ordering.
Ignoring cup size for tops. Bikini top sizing depends on both band and cup measurements, not just clothing size. A D-cup woman wearing a size 8 dress won't necessarily fit a Medium top.
Ignoring the fabric-specific sizing guidance. Sizing correctly for the fabric can be the difference between a great fit and an uncomfortable one.
Forgetting to size down in underwire tops. This is Monday's own most-repeated fit tip and one of the most commonly missed.
Buying based on model photos alone. Models typically wear the smallest available size regardless of what's most flattering. Read reviews from customers with body types similar to yours.
Skipping the "Runs small" warning on product pages. Individual product warnings override general sizing guidance.
Not reaching out to Monday's fit specialist team. The brand offers a dedicated customer service and fit specialist team that can help with sizing questions before you buy.
Popular Monday Swimwear Styles Worth Knowing
Understanding fit is only half the equation; matching style to your body type and preferences matters too.
For Casual Beach Days
Malibu Top and Clovelly Top: Popular, versatile triangle-style tops that work across a wide range of body types
Aruba Top: Bandeau style ideal for backless dresses and strapless cover-ups
Palma Top: Slightly more coverage than triangle styles while still feeling summery
For Larger Bust Support
Bordeaux Top, Cala Roja Top, and Kauai Top: Designed with fuller bust support in mind
Underwire options: Provide the most structural support for larger cup sizes
Thicker strap styles: Distribute weight better than thin triangle straps
For Fashion-Forward Looks
The Monday Top: The brand's namesake style, versatile and consistently in the collection
Sorrento Top and Taormina Top: Trend-forward silhouettes for shoppers wanting something distinctive
St. Martinique Bandeau: Bandeau style for versatile bikini top styling
For Bottoms
Monday's bottoms range from very skimpy to more coverage-focused, with options like the Panama Bottom (moderate coverage), Aruba Bottom (skimpy), and more inclusive coverage options. The site's fit guide filters by bottom coverage level, which is worth using.
Materials and Care
Monday Swimwear uses genuinely quality materials that are worth understanding:
84 percent recycled nylon plus 16 percent spandex in most swimsuits, prioritizing sustainability along with performance
Minimal hardware to avoid discomfort and reduce failure points over time
Adjustable straps and ties for customizable fit
UV protection built into most fabrics
Chlorine and saltwater resistance built into the fabric construction
Care tips to extend swimsuit life:
Rinse in cold, clean water immediately after wearing (particularly after chlorine or saltwater exposure)
Hand-wash gently or use a delicates bag in the washing machine
Never use a hot dryer; always air-dry
Store flat rather than hanging (which stretches straps)
Proper care can meaningfully extend a Monday swimsuit's usable life from 2-3 seasons to 5+ seasons.
Honest Limitations Worth Knowing
Being upfront about Monday Swimwear's tradeoffs:
The price is real. Monday Swimwear is genuinely premium at $70-$150+ per top and $70-$120+ per bottom. This is meaningfully more than fast-fashion swimwear brands. The value proposition holds for buyers who prioritize fit and quality over quantity.
Sizing complexity is a real learning curve. The P-VVV alpha system and fabric-specific guidance mean first-time buyers should genuinely study the fit guide before ordering.
International shipping delays can happen. For US buyers, Monday Swimwear ships from Los Angeles, but international shipping can take longer than domestic timelines.
Return policy specifics vary. Confirm current return terms before ordering, particularly for hygienic reasons (bikini bottoms and one-pieces often have specific return conditions).
When Monday Swimwear Runs Its Best Sales
Timing genuinely matters for value:
End-of-summer sales (August to September). The deepest annual discount window as summer inventory clears for the following year.
Black Friday and Cyber Monday. Meaningful sitewide discounts, though smaller than end-of-summer clearance for specific styles.
Presidents' Day and Memorial Day sales. Early-season promotional windows worth timing summer purchases around.
Newsletter signup discount. New subscribers typically receive a welcome discount code plus early notice of upcoming sale events.
Sample sales and archive sales. Occasionally offered for older styles at meaningful discounts.
The Bottom Line
Finding the perfect fit with Monday Swimwear comes down to understanding the brand's distinctive P-VVV alpha sizing system, following the fabric-specific fit guidance (size down in underwire and crinkle, size up in chevron), and measuring yourself accurately before ordering. Combined with reading the "Runs small" warnings on individual product pages and reaching out to Monday's fit specialist team when in doubt, most buyers can find genuinely well-fitting swimwear on their first or second order rather than working through multiple returns.
For verified discounts on Monday Swimwear tops, bottoms, and cover-ups, bookmark our Monday Swimwear promo code, where we track current offers so you can invest in premium fit without paying full retail on pieces that regularly go on sale.