Stackmat Timer: How to Use It Like at a Competition

What is a Stackmat?

The Stackmat is a timer set from the company Speed Stacks. It comes with a mat and a timer that has two touch pads, one for each hand. It was first made for sport stacking (stacking cups at speed). According to the Speedsolving Wiki, the WCA chose the Stackmat as its official timer right from when it was founded in 2004.

!A Stackmat timer on its mat, with the display showing a time Photo: [Protocoldoug / Wikimedia Commons](https://commons.wikimedia.org/wiki/File:Stackmatresized.jpg), CC0

What makes it different from an ordinary stopwatch: you have to use both hands to stop it. The Speedsolving Wiki says one reason for this is so solvers don't knock the cube over when they rush to hit the button.

A Stackmat set has:

• Two touch pads, one on each side, where your fingertips go.
• A display that shows the time.
• A reset button to set the time back to 0, and a power button.
• A mat to put the cube on while you solve.

Stackmat versions: G3, G4 and G5

The Speedsolving Wiki lists five versions of the Stackmat. If you are buying one today, only the last three really matter:

The timer measures to the thousandth of a second, but WCA results are only recorded to the hundredth of a second.

The G5 has two extra features to stop accidents: the reset and power buttons have to be held for 0.2 seconds before they work, and the buttons are locked for 0.5 seconds after every stop (Speedsolving Wiki).

From 2027: the G5 in 4-pad mode

In August 2026, the WCA announced that from 2 January 2027, every official attempt timed with a dedicated timer must use a Speed Stacks G5 in 4-pad mode (WCA).

The reason the WCA gave: with two touch pads, judges often can't spot mistakes when the timer is started and stopped. The new way to place your hands will be written into a rules update that the WCA is publishing for feedback; when this post was written, the exact hand position was not yet in the announcement. The WCA also said that existing records stay as they are, and that for most cubers the difference in time between the two modes is tiny.

If you plan to buy a cube timer to practise for competitions, the G5 is the safest choice, because it is the only version with a 4-pad mode.

How to start a solve like at a WCA competition

Here are the steps from the current WCA rules (2-pad mode). Practise them properly at home and you won't have to think about them at a competition.

1. Timer at 0. The judge turns the timer on and resets it. You may also reset it yourself before you start (Regulations A3b, A3c3).
2. Inspection. The judge lifts the cover off the cube, and you have under 15 seconds to pick the cube up and look at it. The judge will call out when 8 seconds and 12 seconds have passed (Regulations A3a1, A3b3, A3b4).
3. Put the cube down on the mat, not on the timer. Putting it on the timer gets a +2 penalty (Regulation A3d).
4. Put your hands on the touch pads: palms facing down, fingertips touching both pads, and your hands not touching the cube (Regulations A4b, A4b1).
5. Lift your hands to start. The timer starts when your hands leave the pads (Regulation A4d).

With a Stackmat, you need to keep your hands on the pads for a moment until the timer shows it is ready; lift them too early and the timer won't start. Get the hang of how long your own timer needs you to hold.

Inspection time limits (Regulations A4d1, A4d2):

• Start solving before 15 seconds: fine.
• From exactly 15 seconds to under 17 seconds: +2 penalty.
• 17 seconds or more: the attempt is a DNF (Did Not Finish, it doesn't count).

How to stop the timer the right way

Most penalties beginners get happen when they stop the timer, because their hands are in a hurry.

1. Let go of the cube completely first, then stop the timer. Still touching the cube when you stop it gets a +2 (Regulation A6c).
2. Put both hands flat on the two touch pads to stop it.
3. Don't touch the cube again until the judge has finished checking it. Making one more move after stopping is a DNF; touching the cube without turning it can get a +2 (Regulation A6e).
4. Don't reset the timer until both you and the judge have signed the score sheet, or you may get a DNF (Regulation A6f).

Finally, the judge writes down the result and signs, then you check the number and sign too (Regulation A7). A penalised attempt is written as "time + 2 = result".

Common mistakes with a cube timer

• Slamming the pads too hard to stop. The timer can slide, or the cube can get bumped after you stop. Practise placing your hands quickly but gently.
• Stopping with one hand. At home the timer may still stop, but at a competition you must use both hands.
• Fingers touching the cube at the start. The cube should sit fully on the mat, a little away from your hands.
• Forgetting to reset before the next solve, so the next solve starts from the old time. Make checking that the display is back at 0 a habit.
• Batteries running out in the middle of practice. Always keep spare batteries ready.

No Stackmat? How to practise anyway

You don't need to buy a timer straight away. According to Ruwix, computer timers usually use the Space bar to start and any key to stop. Ruwix also points out the downside: you don't have to put the cube down and pick it up again like you do with a Stackmat.

EasyRubic's online Rubik's Cube timer works exactly that way:

• On a computer, hold the Space bar until the timer shows it is ready, let go to start, and press any key to stop.
• On a phone, touch and hold the timer area, let go to start, and tap again to stop.
• You can turn on 15-second inspection, and the timer works out +2 or DNF on its own, just like at a competition.
• It gives you scrambles, works out your Ao5 and Ao12 for you, and has its own page for every cube from 2x2 to 7x7.

To get used to the Stackmat even when you practise on a computer, put the cube down on the table yourself before you start, and let go of it before you press stop. That habit will come with you into the competition room.

Want to understand the numbers on the timer? See the post on how to work out Ao5 and Ao12. Want to know how a whole competition day goes? See the post on WCA Rubik's Cube competitions.

Video

Want to see it in motion? The short video below from the Hải Muối Rubik channel on YouTube shows more of what this post covers. It is in Vietnamese. The video belongs to that channel and is embedded straight from YouTube.

Sources

• WCA Regulations
• Adoption of 4-Pad Timing (August 2026) – World Cube Association
• StackMat – Speedsolving.com Wiki
• Stackmat and Other Speedcube Timers – Ruwix