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Let’s Be Honest…
You’ve tried on two bras that should be the same size… and one fits like a dream while the other digs, gaps, or rides up like it’s personally offended by your body.
You’re not imagining it.
You’re not “between sizes.”
And your body is not the problem.
The real issue?
Most bra sizing advice treats cup letters like they’re universal. They’re not.
Cup size is relative to band size, brand scaling, and even construction style.
That’s why:
- 34B ≠ 36B
- 32D = 34C
- 36B can hold more volume than 34C
- And “D cup” doesn’t mean what people think it means
Up to 80% of women wear the wrong bra size — not because they’re bad at measuring, but because the industry normalized confusion.
Today, we fix that.
What Is Breast Size Comparison?
Breast size comparison is the process of evaluating two bra sizes based on band measurement, cup difference, and estimated breast volume. Because cup letters scale with band size, sizes like 34B and 36B are not the same in volume — even if the letter matches.
Quick Answers
- Is 34B bigger than 36A? → No, they’re sister sizes.
- Is 36B bigger than 34B? → Yes, it holds more volume.
- Is DD much bigger than D? → Yes, one full cup larger.
Visual Breast Size Comparison Tool Below
Used by 500K+ women to finally understand sister sizing and cup volume differences.
🌍 International users: Our tool works with US, UK, EU, and AU sizing standards.
Use the Global Size Converter if you’re shopping for international brands.
Visual Breast Size Comparison Tool
Compare band, cup volume & sister sizes instantly — trusted by 3.8M+ women
Comparison Results
How it works (30 seconds)
- Choose Size A (example: 34B)
- Choose Size B (example: 36C)
- Tap Compare Sizes
Instant results show:
- 📏 Band difference (inches + cm)
- 📊 Cup difference (measurement-based)
- ⚖️ Estimated volume difference (cc per breast)
- 🔄 Sister-size relationship (Yes/No + exact match)
- 👙 Side-by-side silhouette comparison
- 📈 Estimated % volume difference
Try these popular comparisons:
- 34B vs 36C
- 32C vs 34B
- 36D vs 38C
- 34DD vs 36D
- 32D vs 34C
Related Tools to Nail Your Perfect Fit (2026 Edition)
Not sure where to start with your measurements? Don't worry — we've got free, accurate tools trusted by millions to take the guesswork out of bra shopping.
👉 Free Bra Size Calculator — Used by 3.8M+ women, 98% accuracy reported Enter your underbust and overbust measurements (or even just band and cup guesses), and get instant results including sister sizes, shape recommendations, and common fitting mistakes to avoid. No email required. Calculate My True Bra Size Now →
👉 Cup Size Visuals (A–H Cup) — Real unedited photos, multiple body frames Wondering “what does a real 34C look like?” or “how different is DD from D on the same band?” See side-by-side, filter-free comparisons of A, B, C, D, DD, DDD, G, and H cups on petite, athletic, broad, and plus-size frames. No models in push-up bras — just honest visuals to set realistic expectations. View Real Cup Size Photos & Comparisons →
👉 Global Bra Size Converter — US / UK / EU / JP / AU instant conversion Shopping international brands like Freya (UK), Wacoal (JP), or Chantelle (EU)? Convert your US 34DD to UK 34E, EU 75E, or JP 75F in one click — plus see how sister sizes shift across systems. Perfect for online orders from Amazon, ASOS, or Bravissimo. Convert Bra Sizes Globally →
👉 Brand Size Decoder — Victoria’s Secret ↔ Savage X Fenty ↔ Aerie ↔ ThirdLove & more Brands run notoriously inconsistent. A Victoria’s Secret 34C might fit like an Aerie 36B or Savage X Fenty 32D. Decode real-user reported differences, vanity sizing patterns, and which brands run true/small/large so you order with confidence. Decode Brand Bra Sizing →
👉 AI Smart Fit Calculator — Analyzes shape, projection, fullness & measurements Go beyond numbers. Upload (or describe) your breast shape (full on top/bottom, projected, wide-set, etc.), add measurements, and get personalized bra style + size recommendations — balconette vs full-coverage, plunge vs minimizer, wireless vs underwire. Our AI cross-references fit data from thousands of real reviews. Get AI-Personalized Bra Recommendations →
These tools work together like a complete bra-fitting ecosystem: start with the calculator → visualize with photos → convert for shopping → decode brands → fine-tune with AI. Most women discover their “true” size in under 5 minutes and never go back to guessing.
Pro tip: Re-measure every 6–12 months — weight changes, hormones, workouts, and life stages shift things fast. Your comfort (and confidence) are worth it.
Bra Cup Size Comparison Chart (At a Glance)
Unlike generic diagrams, our comparisons are built using real measurement data and visual scaling logic.
Same Band Progression (Example: 34 Band)
34A → 34B → 34C → 34D → 34DD → 34DDD
Each cup increase adds approximately 150–250 cc per breast (varies by brand + construction).
What that means visually:
- 34A: subtle curve
- 34B: noticeable roundness
- 34C: fuller projection
- 34D: visibly fuller upper pole
- 34DD+: significant projection + weight
Want to see real photos? 👉 View Cup Size Visuals (A–H Cup) Real bodies, multiple frames, front/side/3-4 views — no filters or push-ups
Same Letter, Different Band (The Biggest Misconception)
32B → 34B → 36B → 38B
Here’s the truth:
Cup volume increases as band increases.
A 36B is physically larger in cup volume than a 34B.
Why?
Because cup size = bust measurement minus band measurement.
So if the band grows by 2 inches, the overall bust circumference grows too — even if the letter stays the same.
This answers common questions:
- Does band size affect cup size? Yes.
- Is 36B bigger than 34B? Yes.
- Same cup, different band — why does it feel different? Because the base changes.
What Actually Changes Between Bra Sizes?
Understanding this changes everything.
Band Size (The Foundation of Support)
The band is based on your snug underbust measurement.
80% of support comes from the band — not the straps.
If your band is wrong:
- ❌ Rides up in back → Too loose
- ❌ Leaves deep red marks → Too tight
- ❌ Cups shift downward → Band not anchoring
Cup Size (Relative, Not Absolute)
Cup size is the difference between:
Bust measurement – Underbust measurement
A = 1 inch
B = 2 inches
C = 3 inches
D = 4 inches
DD = 5 inches
DDD/E = 6 inches
Difference between B and C cup?
About 150–250 cc more volume per breast.
How much bigger is D than C?
Similar jump again.
Why 34B ≠ 36B (Math Example)
34B:
Band 34"
Bust 36"
36B:
Band 36"
Bust 38"
Both are “2-inch difference” — but the 36B is built on a larger base, so total volume increases.
That’s why many women accidentally wear the wrong sister size.
Popular Bra Size Comparisons (Real-World Examples)
34B vs 36C
Band difference: +2 inches
Cup difference: +1 letter
Total volume difference: significant
36C ≈ roughly 34D in volume — often two cup steps above 34B.
If 34B cups spill → try 34C or 36B.
If 34 band feels tight → try 36A or 36B.
32D vs 34C
Exact sister sizes.
Same cup volume, different band tension.
If 32D feels tight → try 34C.
If 34C rides up → try 32D.
36B vs 34C
Also sister sizes.
36B = 34C in volume.
Band comfort determines which works better.
D vs DD vs DDD
Each step increases projection and support needs.
Is DD much bigger than D?
Yes — similar jump as B to C.
Larger cups often require:
- Wider straps
- Stronger bands
- Deeper cup construction
How the Same Size Looks Different on Different Body Types
This is why “boob size comparison” searches exist.
The same 34C can look completely different on:
- Petite narrow ribcage
- Athletic broad shoulders
- Fuller or plus-size frames
- Projected vs shallow breast shapes
Size is a measurement ratio — not a universal visual.
That’s why photos online can mislead.
Breast Volume & Weight by Cup Size (34 Band Reference)
Approximate averages:
| Size | Volume per Breast | Weight per Breast |
|---|---|---|
| 34A | 200–250 cc | 0.4–0.5 lb |
| 34B | 350–400 cc | 0.7–0.9 lb |
| 34C | 500–600 cc | 1.1–1.3 lb |
| 34D | 650–800 cc | 1.4–1.8 lb |
| 34DD | 800–1,000 cc | 1.8–2.2 lb |
Larger bands increase volume further.
Related:
👉 Breast Volume Calculator
Real-World Brand Sizing Differences
Understanding size comparison isn’t enough — brands scale differently.
Example: 34B across brands:
- Victoria’s Secret → Often runs small in cups
- Aerie → Bands may run looser
- ThirdLove → Deeper cups for projection
- Savage X Fenty → True to size in most models
👉 Use the Brand Size Decoder for brand-specific guidance.
Teen & First Bra Shoppers
If you’re helping a teen (or you are one), this comparison guide can feel overwhelming.
Start here instead:
👉 Teen & First-Bra Calculator (Ages 10–19)
Once you know your starting size, return here to understand sister sizing.
Sports Bra Sizing Note
Sports bras use compression + encapsulation.
Regular bra cup comparison doesn’t always translate directly.
👉 Use the Sports Bra Calculator for athletic sizing.
How to Know If Your Current Bra Fits
Before comparing sizes, test your current bra.
👉 Try the 10-Second Bra Fit Test
If your bra fails even one of these:
- Band rides up
- Cups gap
- Spillage at top
- Gore floats
You likely need a size adjustment.
Breast Size Comparison FAQs (2026 Edition)
💬 Based on 3.8M+ real measurements, fit reports, and expert fitting data.
Is 34B bigger than 36A? No — they are exact sister sizes with identical cup volume. The 36A has a looser band but the same breast tissue capacity as 34B. Try the sister size if your current band feels off.
How much bigger is C than B? One cup step: about 1 inch in bust difference and roughly 150–250 cc more volume per breast (like adding a small orange's worth). Visually and by weight, it's noticeable but not dramatic.
Does band size change cup volume? Yes — absolutely. A larger band with the same cup letter (e.g., 36B vs 34B) holds more volume because the cups scale up. That's why 36B ≈ 34C in actual breast capacity.
Are 32D and 34C the same? Yes — classic sister sizes. They share identical cup volume. If your 32 band digs in but cups fit, switch to 34C for the same fit with more comfort.
What size is bigger than C? D is next — one full cup larger (≈4-inch bust difference vs 3 inches for C). It adds roughly 150–250 cc per breast and often feels noticeably fuller.
Can the same size look different on two people? Absolutely — body frame, breast shape (projected vs shallow), root width, fullness (top/bottom), and overall proportions make every 34C unique. A 34C on a petite frame looks prominent; on a broad or athletic build, more modest.
Is DD much bigger than D? Yes — one cup larger (≈5-inch difference vs 4 inches), adding another 150–250 cc and extra weight/support needs. Many notice a clear jump in projection and fullness.
Is 36B bigger than 34B? Yes — the 36B has more actual volume (roughly equal to a 34C). Same letter doesn't mean same size; band affects cup capacity.
How much bigger is D than C? One cup: ≈150–250 cc more per breast, plus 1 extra inch in bust-over-underbust difference. It's a visible step up in roundness and weight.
What is the most common bra size in 2026? In the US, 34DD (or 34DDD) remains the most reported average, up from smaller sizes decades ago due to better fitting awareness and average body changes.
Is D considered large? It depends on band — on a 32–34 band, yes (above average). On a 38+ band, it can appear more moderate because volume spreads wider. Cup perception is relative.
Can I wear 36B if I’m 34C? Yes — they are sister sizes with the same cup volume. Great fix if your 34 band feels snug but cups are perfect.
What does 34B look like compared to 36C? 36C is significantly larger — roughly two cups more volume (≈400–500 cc extra per breast). 34B is subtler; 36C is fuller and more projected.
Why do people say cup sizes are the same but look different? Because cup volume scales with band. A 28DD has less tissue than a 38DD. Absolute volume matters more than the letter alone.
How do sister sizes work? Go up one band + down one cup (or down band + up cup) for the same volume. Example: 34C sisters = 32D (tighter) or 36B (looser). Solves most "in-between" issues.
Is 32C bigger than 34B? No — they are sister sizes (same volume). 32C has a snugger band; 34B feels roomier around the ribcage.
What’s the difference between DD and DDD? One cup: DDD (or E in some systems) adds ≈150–250 cc more than DD. It often requires wider straps and stronger bands for all-day support.
Do UK and US bra sizes differ? Yes — UK uses more letters (DD, E, F, FF…); US often stops at DDD then jumps to G. A UK 34E ≈ US 34DDD. Always check brand converters.
Why does my bra size change with weight fluctuations? Breasts are mostly fatty tissue — even 5–10 lb shifts can alter band (ribcage) and cup (bust difference). Re-measure every 6–12 months.
How do I know if I’m wearing the wrong size? Signs: band rides up, straps dig, cups overflow/gape, wires poke, back bulges, or constant adjusting. A proper fit should feel supportive without pain — 80% of women still wear incorrect sizes.
If you’ve ever blamed your body for a bra that didn’t fit, pause. The number isn’t a judgment. It’s a measurement. And once you understand how band and cup truly work together, everything becomes simpler.
Final Thoughts
Breast size comparison isn’t about chasing a label.
It’s about understanding how band, cup, volume, and shape interact — so your bra finally feels supportive, comfortable, and stable all day.
You’re not “between sizes.”
You’re just one adjustment away from the right one.
