How the game works
The math of half
Half the drink is not half the height. Your eyes measure up and down. The glass measures volume. Here's why those two disagree, and how to win anyway.
Play today's glasses →Why half the height isn't half the drink
In Half Full you pour into a strange glass and try to stop at exactly half. Half by volume, meaning half the drink the glass can hold. That's not the same as filling it to half its height, and the gap is the whole game.
Think of any glass as a stack of thin, round slices, like a pile of coins. Each slice holds π × radius² × thickness of drink. That little ² is doing a lot of work.
2× wider = 4× the drink
A slice that's twice as wide holds four times as much. So the wide parts of a glass soak up most of the volume, and the narrow parts barely count. Half the drink always gets pulled toward wherever the glass is widest.
The only glass where half the height equals half the drink is one with perfectly straight, up-and-down sides: a cylinder, where every slice is the same. A shape that's mirror-symmetric top to bottom, like a perfect ball, also lands at exactly 50%. Every other glass cheats one way or the other.
The martini problem
A martini bowl is basically a cone standing on its point. Its width grows in a straight line from the bottom to the rim. Here's where half the drink ends up, in four steps:
width ∝ hAt height h, the cone is h-wide (times some constant). Twice as high, twice as wide.slice area ∝ h²Area goes with width squared.volume ∝ h³Stack up all the slices from the point to h. Same reason a cone twice as tall and twice as wide holds 2 × 2 × 2 = 8 times as much.(h/H)³ = 1/2, so h = 0.794 HSet the volume to half the full glass (H is the full height). The cube root of 1/2 is 0.794.
Half the drink in a cone sits at 79.4% of the height. Flip it around and it gets worse: fill a cone to half its height and you've poured (1/2)³ = 1/8 of the drink. That's 12.5%.
The martini in the game has a tiny flat spot at the bottom instead of a sharp point, which nudges its half line down a hair, to about 78%. Still way higher than it looks.
For the nerds: for any glass, the drink up to height h is π × r(y)², added up (integrated) over every height y from the bottom to h, where r(y) is the glass's radius at height y. The half line is the h where that reaches 50% of the total. The π cancels out, so only the shape matters, not the size.
Four glasses, filled to the real half
These are drawn from the game's own glass formulas (each set to the middle of its usual range, except the hourglass, whose waist we nudged down to make a point) and filled to exactly half the drink. Heights are measured inside the glass, from the bottom of the drink to the rim. Stems don't count.
- drink at the true half
- half the drink
- half the height
Where half sits in all 14 glasses
Every glass type has a few dials, like how pinched the bottom is or where the waist sits, so each day's version is a little different. The big number is the half line with every dial in the middle. The small range covers every setting the game can pick. Glasses also come bigger or smaller, which never moves the half line.
| Glass | Shape | Half sits at | Tip |
|---|---|---|---|
| Tumbler | Straight sides, a little wider at the rim | 55.5%53–58% | Aim a notch above the middle. Half the height only holds about 44%. |
| Pint glass | Flares out from a narrower base | 58.3%56–60% | A bit higher than the tumbler, just under three-fifths of the way up. |
| Martini glass | A cone that comes almost to a point | 78.4%78–79% | About four-fifths up. It will look way too full. Trust the math. |
| Coupe | Shallow, rounded bowl, widest at the rim | 63.9%63–65% | Just under two-thirds of the way up. |
| Wine glass | Tulip: bulges out, then narrows toward the rim | 60.6%57–64% | Half lands near the fattest part of the bowl, often a little below it. |
| Fishbowl | A ball with its top and bottom sliced off | 52.8%49–57% | Find the widest point. Half sits right there or a touch below. |
| Flask | Wide base tapering straight into a skinny neck | 19.1%16–22% | Only a fifth of the way up. The neck holds almost nothing. |
| Vase | Round belly low down, slim neck, flared lip | 34.1%29–39% | Just above the widest point of the belly. |
| Hourglass | Two bulbs with a narrow waist near the middle | 50.0%21–79% | Half always lands in the bigger bulb. Waist below the middle? Half is up top, and the other way around. |
| Pilsner | Tall and slim, curving out toward the top | 72.1%68–76% | Nearly three-quarters of the way up. |
| Margarita glass | A small bowl at the bottom, then a wide flared top | 75.5%72–79% | The little bowl is a trap. Half sits high, up in the wide top. |
| Tiki mug | Ringed, bulging sides, a little narrower at the top | 45.1%43–48% | Just under the middle. Count the bulges instead of guessing. |
| Light-bulb glass | A narrow tube that opens into a big round bulb | 59.6%56–63% | Ignore the tube. Half sits a little below the fattest part of the bulb. |
| Twisted glass | A rounded square that twists and narrows as it rises | 37.9%35–41% | Low, because the wide bottom holds most of it. The twist changes nothing. |
The hourglass is the wild card. With its waist dead center it's a perfect 50%, but the waist is narrow, so even a small shift in where it sits sends the half line racing past it into the bigger bulb.
Why doesn't the twist matter? Turning a slice doesn't change how much it holds. Only how big each slice is counts, so a twisted glass fills exactly like an untwisted one of the same size.
Tilted glasses
Some days one glass leans over. The drink doesn't lean with it: its surface always stays level, so it cuts across the glass at a slant. The half line becomes a slanted ring, deeper on the low side than on the high side.
The math is the same idea, just sliced the other way. The game cuts the glass into thin round slices along its middle, works out how much of each slice sits below the drink's level surface, and adds them up. Half the drink is still half of what the glass holds standing up.
Two things change. A leaning glass spills sooner, as soon as the drink reaches the low side of the rim. And the reveal tells you where you stopped measured up the glass's middle, since there's no single height on a slant. The table above is for glasses standing up straight.
How we score you
The game tracks how much drink is in the glass as a share of what the glass can hold. When you lock in, your score is:
100 − 4 × (how far you are from 50%)
That's 4 points lost for every percentage point of volume you're off, rounded to a whole number and never below zero. Over or under counts the same. A perfect 100 means landing within an eighth of a percent of half, so when you're close, the game shows your pour to one decimal.
- 50% → 100
- 48% or 52% → 92
- 45% → 80
- 40% → 60
- 30% → 20
- 25% or less, 75% or more → 0
- filled to the brim → spill → 0
Each day there are 5 glasses: one warm-up (a tumbler or a pint glass), then four harder ones, all different shapes, sometimes with one of them leaning. That's up to 500 points. Everyone gets the same glasses on the same date, so you can compare with everyone who played today. A new set arrives at midnight your time.
The eyeball test
What if you skipped the math and filled every glass to exactly half its height? Here's what you'd score with each glass set to the middle of its range:
- Fishbowl 86
- Tiki mug 84
- Tumbler 78
- Pint glass 66
- Twisted 48
- Wine glass 41
- Coupe 33
- Light bulb 32
- Pilsner 8
- Martini 0
- Flask 0
- Vase 0
- Margarita 0
The hourglass depends entirely on where its waist sits.
Tips to pour better
Find the widest part first. That's where the drink lives. Half gets pulled toward it: high in a martini, low in a flask, into the bigger bulb of an hourglass.
Flip to the 3/4 view. From above you can see how big the drink's surface is. A big surface means every millimeter adds a lot of drink, so ease off.
Draw a guide mark before you pour. Use the table above as your first guess and draw a line on the glass. Your marks stay pinned to the glass when you swing the view.
Watch how fast the surface moves. The level races through skinny parts and crawls through wide ones. If it suddenly speeds up, you've hit a narrow section. (Every glass pours at its own speed, so counting seconds won't save you.)
Pour in bursts, then drain to fine-tune. Draining is slower than pouring, which makes it good for small fixes. Just never let it reach the rim. On a keyboard: hold Space to pour, hold D or ↓ to drain, and press Enter to lock in.
FAQ
Is the half line exact?
Yes. Every glass is a precise mathematical shape. The game cuts it into 1,000 thin slices, adds up how much each one holds, and finds the height where the running total hits 50%. Your pour is measured in volume too, so there's no guessing on our side.
Why does the martini feel so wrong?
Because your brain judges height, and a cone hides almost nothing at the bottom. The lower half of a perfect cone's height holds just 1/8 of the drink (about 14% in the game's martini). So the correct pour, around 78% of the way up, looks like you've overdone it.
Is there a trick?
The trick is the math. Find where the glass is widest, remember that width counts twice, and use the table as your starting point. Then fine-tune with the drain. No secret button, sorry.
Do bigger glasses count for more?
No. Your score is based on the share of each glass's own volume, and making a glass bigger or smaller without changing its shape doesn't move its half line. Every glass is worth up to 100.