Odd One Out Tips: Spotting Faint Colour Differences Against the Clock

Updated October 2026

Odd One Out looks like a pure eyesight test: twenty-five coloured squares, one of them a touch lighter or darker than the rest, and a minute to find as many as you can. In reality your score depends just as much on how you search and how you handle doubt as on how sharp your eyes are. This guide covers how much the colours really differ on each board, how the clock and the penalty work, when a guess is worth taking, and how to practise so that your search speeds up as the boards get harder.

What changes from board to board

Every board is a 5 by 5 grid painted in one colour, with a single tile that differs only in lightness. The main colour is fresh each board: any hue around the colour wheel, a fairly strong saturation between 60 and 79 percent, and lightness fixed at the middle value of 50 percent. The odd tile keeps the same hue and saturation, and is shifted either lighter or darker, with equal chances.

The shift is what makes the game harder. It starts at 30 percentage points of lightness, and every time you clear a board it is multiplied by 0.92. That gives roughly these values:

• Board 1: a 30-point difference, obvious at a glance.
• Board 6: about 20 points.
• Board 11: about 13 points.
• Board 16: about 8.6 points.
• Board 21: about 5.7 points, where most players start to slow down noticeably.
• Board 26: about 3.7 points.
• Board 34 onward: the shift stops shrinking at its floor of 2 points and stays there for the rest of the minute.

Because the base colour changes every board, nothing carries over between them. You cannot learn "the odd one is usually darker", and the position of the odd tile is picked at random among all twenty-five cells every time, so it can even appear in the same spot twice running.

How the clock and penalty work

You get 60 seconds in total, not per board. The clock does not start when the page loads; it starts on your first tap. That first tap also counts as an answer, so the opening board is effectively free thinking time: study it as long as you like, then tap the odd tile to start the minute and clear board 1 in the same motion.

Each tap on a wrong tile takes 2 seconds straight off the remaining time and flashes that tile with a red outline for a fifth of a second. Nothing else happens; the board stays, and you can keep searching. Each correct tap immediately replaces the board with a new one and adds one to your score, which is simply the number of boards you cleared. The timer is based on real time, so switching away from the game does not stop it.

It helps to think about the pace these rules imply. Clearing 30 boards in a minute means two seconds per board on average, including the tougher boards near the end. Every wrong tap costs as much time as an entire board at that pace.

When to guess, and when not to

The penalty gives you a simple way to decide. Suppose you have narrowed it down to a few candidate tiles and simply tap them one after another until you hit the right one. With two candidates you will waste one tap half the time, an average cost of one second. With three candidates the average is two seconds, with four it is three, and in general it is one second for every candidate beyond the first.

So if you are torn between two tiles and settling it by looking would take longer than about a second, just tap one; if it was wrong, the other is right. With three or more candidates, keep looking a little longer, because a third tile costs as much as a whole board at a good pace. A random stab with no idea at all is the worst choice: on a 25-tile board the expected cost is around 24 seconds.

Searching faster than tile by tile

Inspecting tiles one at a time works on early boards and collapses later, because a tiny shift is easier to notice when the odd tile sits next to normal ones in your view. A few methods work better:

• Take in the whole grid first. Rest your eyes on the centre tile for a moment without hunting. Large differences usually stand out within a fraction of a second on their own.
• Sweep in strips. If nothing appears, scan the grid as five rows, judging each row as a single band of colour. A tile that breaks the evenness of a band is easier to see than one judged by itself.
• Do not neglect the border. Sixteen of the twenty-five tiles sit on the outer ring, so the odd tile lands there almost two times out of three. Many players stare at the middle and miss tiles in the corners.
• Compare neighbours, not single tiles. Tiles are separated by thin dark gutters, so there is no shared edge to inspect. Instead, judge two adjacent tiles side by side as a pair, moving the pair along the row; a pair that looks uneven tells you the odd tile is one of those two, which feeds straight into the two-candidate rule above.

Your screen and your eyes

On the later boards the shift is only a few points of lightness, and display settings start to matter. Turn the screen brightness up and switch off any automatic dimming for the run. Hold the phone square to your face, since many screens change their apparent brightness as the viewing angle changes. Some colours also show lightness changes better than others: the same numerical step can look clearer on one hue than on another, so do not be surprised if board 22 feels easier than board 19.

Your eyes tire quickly on a task like this. If you start to feel that every tile looks different, that is visual fatigue, and the fix is to look away for a second, not to start tapping.

Common mistakes

• Tapping a tile because it "might" be the one. The first wrong tap is usually followed by a second as panic sets in. Two quick mistakes cost four seconds, two boards' worth of time.
• Burning the free first board. There is no reason to hurry the opening board, because the clock is not running yet. Get your eyes settled and your finger ready.
• Getting stuck on one board. Hard boards near the floor can take a while. If you are past five seconds on one, change method: switch from rows to columns, or from tiles to edges.
• Losing your place. Without a fixed order you will re-examine the same tiles. Stick to one sweep pattern every time.

A practice plan

1. Play a few rounds where you never tap unless you are certain. Note how many boards you clear with zero penalties; that is your clean baseline.
2. Practise the whole-grid glance on the first ten boards, where the difference is still 13 points or more. The goal is to tap the odd tile without having consciously searched.
3. Then add the two-candidate rule: when you are down to two tiles, tap one immediately. Track whether your average score rises.
4. Finally, work on the late boards with the row-and-edge sweep. Once you can clear boards at the 2-point floor in a few seconds, the score is limited only by how steadily you can keep going for a full minute.

Your best result is stored on your device, and you can submit any finished run to the Hall of Fame from the card that appears when time is up.