Stacking for Quads: leave one well open and clear with an I

How to set up a Quad, four lines at once with one I: where the well goes, when to put the I in, how far apart I pieces come in 7-bag and where spare ones go.

October 5, 2026

A Quad is a line clear where you drop an upright I piece into a well and clear four rows at once. Clearing four rows one at a time gives a total base score of 400, but clearing them together gives 800 (the points are the values used in this site’s practice modes). The shape is simple and needs no special slot the way a T-spin does, so it is a good first way of clearing to learn.

The shape: stack nine columns flat and leave one edge column empty

Of the board’s ten columns, leave just one at the edge empty and stack the other nine flat. The empty column is the well. Once four rows are complete across the nine columns, stand the I upright and drop it into the well.

The right edge column is left empty and the other nine columns are filled four rows high. Drop the I upright where the dotted outline is.

The four rows clear at the same time, and only the incomplete fifth row is left.

The well can be at either edge, left or right. At the edge, the other nine columns work as one continuous flat surface. A well in the middle splits the surface into a left and a right half and makes the steps harder to manage.

Do not put the I in until four rows are complete

Just because an I has come, do not put it straight into the well. If you put it in while only a few rows are complete, only that many rows clear. On top of that, the leftover cells of the I stay in the well, and you lose the well.

An I put in when only two rows are complete.

Only two rows cleared (a Double, base score 300). The other two cells of the I are left stacked up at the right edge, and the well is gone.

If an I comes before four rows are complete, hold it, or lay it flat and use it in your stack, as explained below.

You never wait more than 12 pieces for an I

Keeping a well open and waiting for an I may make you nervous. But with 7-bag, every bag of seven pieces contains exactly one I. The longest stretch without an I is when the I comes first in one bag and last in the next, and that leaves 12 pieces in between.

Twelve pieces are 48 cells. Stacked flat on the nine columns outside the well, that is a little over five rows. By this count, once four rows are complete, about six empty rows above them are enough to wait for the I. The board is 20 rows tall, so if you keep your stack low, you have plenty of room. “What is 7-bag? How piece order works” explains how 7-bag works.

Lay spare I pieces flat in your stack

Even if you clear with nothing but Quads, you will in fact have I pieces left over. One Quad clears 40 cells, which is ten pieces’ worth. Only one of them is the I that goes into the well; the other nine pieces’ worth go on the nine columns.

Meanwhile, one piece in seven is an I. Counting pieces alone, seven Quads use 70 pieces, exactly ten 7-bags, and ten I pieces come in that time. Only seven of them go into the well, so the other three I pieces have to go somewhere other than the well.

An I that comes before the well is ready becomes part of the stack if you lay it flat on four level cells.

Keep the I in hold

If an I comes shortly before four rows are complete, another option is to put it in hold. Once the four rows are complete, you can bring it out of hold and put it straight into the well. But while the I is in hold, you cannot use hold to reorder other pieces. For more on hold, see “How to use Hold”.

How to practise

“40 lines (timed)” in Basic Practice makes ideal practice. Exactly ten Quads finish the 40 lines. At first, do not worry about your time; count how many Quads you made instead. The closer you get to ten, the flatter you are stacking.

Once your Quads are consistent, T-spins come next. A T-spin double has a base score of 1200 for two lines, more than a Quad. Try starting with “T-spin basics: the T-spin double”.

Practice this