A deep neck on a saree or lehenga blouse is different from a deep neck on a dress in one way that changes the answer: the blouse is fitted and usually lined. A dress hangs from the shoulders and leaves the bra to hold everything. A tailored blouse holds the bust itself, so the bra underneath has less work to do and more room to be replaced by something smaller. That is why the first question is not how deep the neck is but whether the blouse is padded.
Is the blouse padded?
A padded blouse has cups sewn into the lining. It covers, and it gives shape, so the bra's usual coverage job is already done. What it does not do is lift, because sewn-in cups hold the breast where it sits.
Under a padded blouse with a deep neck, a normal bra is the worst option: its centre gore sits at the bottom of the V and shows, while the padding makes its cups redundant. Most people wear nothing, or reusable nipple covers where the lining is thin. If you want the line higher than the padding leaves it, the fabric uplift cups sit inside the blouse's own cups and raise the bust without a band or a centre piece anywhere near the neckline. Which bra to wear with a saree covers the padded case against the other blouse cuts.
How deep can a normal bra go under an unpadded blouse?
Until its centre shows. An unpadded blouse needs coverage and support from the bra, and a plunge bra with a low centre gore survives a moderate V. The blouse's fit helps here: because the fabric holds the bust close, a plunge can go a little deeper under a fitted blouse than under a loose dress before it gapes. Past the point where the gore would show, the ladder is the same one described in a bra for a deep neck dress, and it runs like this.
| The neckline | What a normal bra shows | What works instead |
|---|---|---|
| Moderate V or U | Nothing, if the gore is low | A plunge bra |
| Deep V | The centre gore | The strapless adhesive bra, clasp set low |
| Very deep or open to the waist | Gore and inner cup edges | Tape in a V, covers underneath |
| Square neck | Straps and the top edge | The strapless adhesive bra, or the butterfly |
| Sweetheart | The gore at the dip | Stick-on cups placed wide |
When do stick-on cups take over?
At the depth where any centre piece would show. The strapless adhesive bra is a pair of moulded cups with a clasp between them, and the clasp sits lower than a bra's gore does, so the cups can be placed wide and drawn together below the bottom of the V. It is sized like a bra, 30A to 40D, so under a fitted blouse a D gets a real fit. For a square neck, where the problem is the strap line and the top edge rather than the centre, the butterfly stick-on bra anchors high and lifts with nothing at the top edge to show, in cup sizes A-B, C and D-D++.
Shape matters as much as size here. A wide-set or east-west shape gains most from the clasp, and a relaxed shape wants the lift first; breast shapes and what fits each sorts the two.
When is tape the better tool?
When the neck goes below any cup's inner edge, which on a blouse usually means a V that reaches the waist tuck. Boob tape applied from the outside of the breast inward and upward, following the line of the V rather than crossing it, lifts and shapes with nothing in the centre at all. Covers go on first. The placement is the same one used for a deep V dress, and how to apply boob tape has the full steps.
What should you tell the tailor?
The bra you will actually wear. A blouse is fitted around whatever is under it at the fitting, so a blouse fitted over a padded bra and worn over stick-on cups will gape at the neck and pull at the underarm. Bring the cups or the tape to the fitting, or ask for the blouse to be cup-lined if you know you will wear it without a bra. A tailor can also lower the centre of a lined cup to match a deep neck, which is the cheapest deep-neck solution of all.
What about a heavier bust?
The blouse does more of the holding, which is good news. At D and above under a deep neck, the strapless adhesive bra's band sizing is the difference between a cup that holds for a wedding and one that does not, and a fitted blouse over it takes some of the load a dress would leave to the adhesive. A strapless bra for a heavy bust has the full account.
The short version
Padded blouse: covers or nothing, uplift cups if you want the line higher, never a normal bra whose gore will show. Unpadded blouse: a plunge until its centre shows, then the strapless adhesive bra with the clasp set low, then tape in a V for the deepest cuts, with the butterfly for a square neck. Take the real bra to the tailor. If you are holding a blouse and cannot tell which case it is, what to wear under any neckline will take the cut and your cup size and answer it, and the bra size calculator will give you the cup.
