Length is a specific kind of promise, and there are a few different ways to get it. Some tubes make each lash longer, some separate the lashes so they look longer, and some just curl and hold. I like to compare a few side by side on the same day, one eye each.

Lancôme's Lash Idôle Lengthening and Volumizing Mascara is the more polished formula, a bit more dressed up. Benefit's They're Real Lengthening Mascara is the one I reach for when my lashes look short and I want them dark and defined. ILIA's Limitless Lash is a clean lengthening formula, a good one if you want something a little less heavy on the eyes. Prada's Pradascope is made to lift and lengthen, and it feels more like a design object than a mascara, which is half the fun.

Yves Saint Laurent's Lash Clash is the bold one, made for extreme volume, and it deserves an evening rather than a commute. Rare Beauty's Perfect Strokes is a universal volumizing formula, easy to layer and easy on the eyelids.

The test I use: after four hours, look for flakes under the eye and clumps at the outer corner. That tells you more than the first ten minutes ever will.

If you want lashes that look longer on a bare face, the work happens before the tube. A primer goes underneath and gives the mascara something to grip, and a serum, used consistently, is meant to keep lashes looking fuller over weeks.

Lancôme's Cils Booster XL is a primer made to sit under mascara, so whatever dark formula you put over it looks longer and fuller. Tarte's opening act lash primer does a similar job and is a good pair with a washable tube. Dior's Diorshow Maximizer 4D is a primer and serum in one, made for length, volume, curl and definition, and I like it when I want one product rather than two.

Then there are the serums. Grande Cosmetics' GrandeLASH-MD, Olaplex's Lashbond and Vegamour's GRO Volumizing Lash Serum are all applied along the lash line, and the routine matters more than the brand. Apply on clean, dry lids and give them a few weeks before judging.

What I would skip: layering a serum and mascara at the same time in the morning, and sharing your tube with anyone. Change your mascara every few months, and skip any product if your eyes feel irritated or red. If that persists, see an eye doctor rather than trying another formula. Lashes are lovely, but your eyes come first.

To choose, start with what your lashes do naturally. Short and straight lashes need a comb and a curler, thin lashes want a primer, and stubborn ones may just need the right brush.

Try the original first, since it is the one everybody compares against, and it gives you a baseline for how your lashes behave. If it clumps or smudges, move to a lengthening formula with a smaller wand. Keep a waterproof tube for occasions, and always use an oil-free remover so you are not tugging at your lashes. Give any new tube a full week of ordinary days before you decide. Take a photo in daylight and choose the one that looks like your eyes, only awake. And keep a small mirror handy for the first week with any new tube, because that is when you find out how it behaves at the end of a long day, when it matters.