40G vs 40H Bra Size: What Is the Real Difference? (2026 Fit Guide)
Quick Answer: 40G and 40H share the same 40-inch band but differ by exactly one cup size. A 40G fits a bust approximately 48 inches (122 cm) with an 8-inch bust-to-band difference. A 40H fits a bust approximately 49 inches (124.5 cm) with a 9-inch difference. The cup volume difference is roughly 200–220 ml per breast. At 40H, only dedicated full-bust brands (Elomi, Goddess, Panache, Curvy Kate) produce structurally correct cups — ordinary molded bras will fail. Wire width and band precision become critical at this volume.
⚡ Key Takeaways
- One cup apart: 40G and 40H are adjacent sizes — no intermediate cup exists between them.
- Same 40 band: Both fit an underbust of ~39–40″ (99–102 cm) — the band width is identical.
- 40G bust: ~48″ (122 cm) — 8-inch bust-to-band difference.
- 40H bust: ~49″ (124.5 cm) — 9-inch bust-to-band difference.
- Cup volume: 40H holds ~200–220 ml more per breast than 40G — significant structural difference.
- Not sister sizes: Sister sizes change band and cup together. 40G and 40H are on the same band with different volumes.
- Sister size of 40G: 38H (tighter band, same cup) and 42F (looser band, same cup).
- Sister size of 40H: 38I/38GG (tighter band, same cup) and 42G (looser band, same cup).
- International sizing: US 40G = UK 40G (8″); US 40H = UK 40GG (9″); UK 40H = 10″ differential.
- Wire width critical: At G/H, choose brands based on wire width (wide: Elomi/Goddess; narrow: Panache).
- Construction: 40H requires 4-part cups + side slings + 4-hook bands mandatory.
- Weight: ~4–4.8 lbs total breast weight at 40H — band must carry 80–90% of this.
40G vs 40H: The Core Difference Explained
Both 40G and 40H are built on the same 40-inch band. The band’s circumference, hook-and-eye length, and strap attachment points are identical. However, at G/H cup levels, the underwire span (how wide the wire extends across the chest) varies significantly between brands — this becomes as important as cup volume.
The cup difference is exactly one size when brands separate G and H:
- 7″ difference = F cup
- 8″ difference = G cup
- 9″ difference = H cup (or GG in UK)
- 10″ difference = I cup (or H in UK)
The UK vs US G/H Progression
UK brands insert “GG” between G and H:
- UK: G (8″) → GG (9″) → H (10″)
- US (simplified): G (8″) → H (9″) [skips GG]
- US (full): G (8″) → GG (9″) → H (10″)
This means US 40H may equal UK 40GG or UK 40H depending on the brand’s system. Always verify by bust measurement: 49″ bust on 40 band = 9-inch cup.
The One-Cup Volume Difference Visualised
40H holds one full cup more volume than 40G — same band, adjacent sizes. At H cup, 4-hook bands and wide wire options are essential.
Because 40G and 40H are adjacent sizes, there is no intermediate cup. If your 40G cups spill or the centre gore lifts, move directly to 40H. If your 40H cups gap, move directly to 40G.
Measurement Breakdown: 40G vs 40H
The table below shows exactly how each size is derived from body measurements and their international equivalents.
| Measurement | 40G | 40H |
|---|---|---|
| Underbust (Band) | ~39–40″ (99–102 cm) | ~39–40″ (99–102 cm) |
| Bust (Fullest Point) | ~48″ (122 cm) | ~49″ (124.5 cm) |
| Bust-to-Band Difference | 8″ (20 cm) = G cup | 9″ (23 cm) = H cup |
| Approx. Cup Volume | ~1750 ml per side | ~1960 ml per side |
| US Equivalent | 40G | 40H (or 40GG if brand uses double letters) |
| UK Equivalent | 40G | 40GG (9″) or 40H (10″) — check brand |
| EU Equivalent | 90H | 90I (or 90J depending on system) |
| Typical Weight | ~1.8–2.0 lbs per breast | ~2.0–2.4 lbs per breast |
Total weight at 40H: Approximately 4–4.8 lbs of breast tissue. This is why band fit is absolutely critical — the band must carry 80–90% of this weight.
Wire Width: The Critical Factor at 40G and 40H
At G and H cup levels, wire width becomes as important as cup volume. Different brands engineer wires for different breast root widths:
Wide Wire Brands (Better for Broad Breast Roots)
- Elomi — Known for wide, comfortable wires that extend further back on the ribcage
- Goddus — Wide wires with 6-part cup construction
- Sculptresse (by Panache) — Wider wire options
Narrow Wire Brands (Better for Narrow Breast Roots)
- Panache — Narrower wires, more projected cups
- Cleo by Panache — Narrowest wires, best for narrow roots
Sister Sizes: 40G and 40H Each Have Their Own Volume Family
Because 40G and 40H hold different cup volumes, they belong to entirely separate sister size families.
Sister Size Family for 40G
All sizes below hold the same cup volume as 40G:
Sister Size Family for 40H
All sizes below hold the same cup volume as 40H:
38GG (UK)Tighter band
Use our sister size calculator for your complete ladder.
Real Fit Differences Between 40G and 40H
Cup Construction and Band Requirements
At G cup, 4-part seamed cups with side slings are mandatory. At H cup, you need:
- 4-part cups minimum — 3-part will not contain the volume
- Reinforced side slings — stronger than G-cup versions
- 4-hook closure preferred — 3-hooks may roll under ~4 lbs of weight
- Powernet wings — essential for back smoothing and band stability
- Extra-wide straps — 20mm+ with heavy padding
Sports Bra Requirements
At 40H, regular compression sports bras are inadequate. You need:
- Enell — High-impact, up to 52H, encapsulates each breast separately
- Panache Sport — Underwire encapsulated, J-hook racerback option
- Shock Absorber Ultimate Run — Compression + encapsulation combo
Strapless Possibilities
Strapless is extremely limited at 40H. Options include:
- Curvy Kate Luxe Strapless — Up to H cup with silicone grip
- Goddess — Selected strapless styles
- Fashion Forms Ultimate — Backless/strapless combo styles
All require extensive testing for band stability.
Who Should Wear 40G?
- Underbust ~39–40 inches, bust ~47.5–48.5 inches (8-inch differential)
- Centre gore lies flat in 40G without lifting
- No persistent side spillage (scooping resolves any minor overflow)
- Straps sit comfortably without digging
- Band stays level throughout the day
- International: 40G (US/UK) / 90H (EU)
Who Should Wear 40H?
- Underbust ~39–40 inches, bust ~48.5–49.5 inches (9-inch differential)
- Centre gore lifts off sternum in 40G
- Chronic underarm spillage in 40G
- Shoulder strap grooves even with cushioned straps
- Band rides up or rolls in 40G
- International: 40H (US) / 40GG (UK 9″) / 90I (EU)
- Must shop: Elomi, Goddess, Panache, Curvy Kate specialist lines
Where to Find 40G and 40H
Neither size is available at mainstream retailers. Both require full-bust specialists:
- Elomi — Matilda, Cate, Charley up to 46K
- Goddess — Kayla, Keira, Verity with 6-part cups
- Panache — Jasmine, Envy, Andorra
- Curvy Kate — Luxe Strapless (up to H), daily styles
- Online: Bare Necessities, Bravissimo, Breakout Bras, HerRoom
🛍️ Best Bras for 40G and 40H — Our Top Picks
Glamorise Women’s MagicLift Active Support Wirefree Bra #1005
Wire-free support for G and H cup volumes. The internal sling system lifts without underwire, with 3+ hook back for weight distribution. Wide cushioned straps prevent digging at this volume level.
Available in: 30–46, cups B–K
View on Amazon →
Glamorise Women’s WonderWire Front-Close Underwire Bra #1245
Structured underwire with cushioned channel distributes pressure for G/H cups. Front closure design with reinforced side panels. 3+ hook back essential for ~4 lbs of breast weight.
Available in: Up to 48H
View on Amazon →ℹ️ As an Amazon Associate, Bra Calculator earns from qualifying purchases. For 40G and 40H, we strongly recommend full-bust specialists (Elomi, Panache, Goddess) over Glamorise for optimal support.
5-Step Fit Test: Confirm 40G or 40H Right Now
All tissue forward. Overflow at sides means cup too small.
Must lie flat. Any lift = size up.
Wires should encircle tissue without digging into side. If digging, try wider brand (Elomi) before sizing up.
Two fingers under band with firm resistance. At H cup, band must be firm to carry ~4 lbs.
Band stays level during activity. Any riding up = band too loose or cup too small.
Not sure whether 40G, 40H, or a different size is right? Our AI calculator gives you a precise answer.
Try the AI-Powered Bra Size Calculator →
40G vs 40H: Full Side-by-Side Comparison
| Feature | 40G | 40H |
|---|---|---|
| Underbust | 40″ / ~39–40″ | |
| Bust | ~48″ | ~49″ |
| Differential | 8″ | 9″ |
| Volume | ~1750 ml | ~1960 ml |
| UK Equivalent | 40G | 40GG (9″) or 40H (10″) |
| Sister Sizes | 38H, 42F | 38I/38GG, 42G |
| Hook Count | 3–4 hooks | 4 hooks preferred |
| Weight (each) | ~1.8–2.0 lbs | ~2.0–2.4 lbs |
People Also Ask: 40G vs 40H — Answered
Is 40H bigger than 40G?
Yes — exactly one cup size larger. 49″ bust vs 48″. ~200–220 ml more per side.
Is 40H the same as 40GG?
In UK sizing, 40GG = 40H (9″). In US sizing, some brands use H directly (skipping GG). Check brand chart.
How do I know if I’m 40G or 40H?
48″ bust = 40G. 49″ bust = 40H. Gore lift or side spillage in 40G = need 40H.
What is the sister size of 40G?
38H and 42F.
What is the sister size of 40H?
38I/38GG and 42G.
Which brands carry 40H?
Elomi, Goddess, Panache, Curvy Kate, Fantasie, Bravissimo.
Can I wear strapless at 40H?
Very limited. Curvy Kate Luxe, Goddess selected styles, Fashion Forms Ultimate.
Why do my 40G bands roll?
Insufficient grip for ~4 lbs weight. Try 38H (tighter band) or 4-hook styles.
Do I need special sports bras at 40H?
Yes — Enell, Panache Sport, or Shock Absorber Ultimate Run.
How much do 40H breasts weigh?
~2.0–2.4 lbs each, ~4–4.8 lbs total. Band must carry 80–90% of this weight.
