Linear feet is the wrong unit for bead
The instinct on any trim material is to add up the runs, divide by the stock length and round up. For bead that answer is always low, and it is low for a structural reason rather than a rounding one: a mitred bead cannot be spliced. Every piece has to come out of one stick in one length. So a stick with three feet remaining after two long pieces have come off it does not contain three feet of bead — it contains three feet of stock that will only take a piece three feet or shorter, and if the schedule has no such piece left, it is waste.
The page therefore does both. It reports the plain division, then it nests the actual pieces: longest first, each one dropped into the first stick with room for it. On the schedule the page opens with, the two answers differ, and the difference is the point of the exercise. It also reports the total offcut, which is the material you are buying and throwing away.
What the cut allowance is doing
Each mitred piece is cut at both ends, and each cut consumes a little stock — the blade width plus whatever the mitre takes at the point. Four pieces to a lite is eight cuts, so a lite with a hundred inch perimeter draws slightly more than a hundred inches from the sticks. On a single sash that is nothing. On sixty lites at an eighth of an inch a cut it is five feet, which is most of a stick.
The field is small and easy to leave alone, and that is fine. What is not fine is setting it to zero and then finding the last sash short by an inch and a half, which is exactly how it presents when the allowance was left out.
Setting blocks, and why the position is a field
Setting blocks carry the weight of the lite and keep it off the rebate. Where they go along the bottom edge is a specification, and the reason it is a field on this page rather than a constant is that the specification is not universal. Quarter points are the figure most people quote. Glazing systems publish their own. Insulated units, laminated builds, long thin lites and heavy pieces are not all treated identically, and the manufacturer of whatever is being glazed has a position on it.
Put their fraction in and the page reports the position in inches for each distinct sash width in the schedule, which is the number somebody actually needs at the bench. Block length, width and thickness all come from the block supplier and depend on the rebate and the glass — the page uses the length only to print it back to you.
Fixings and sealant
The fixing count is a rate per foot of bead, which covers pins, points, clips and screws alike. Snap-in bead needs none, so the field takes zero and the line disappears. Nothing here says what spacing is right, because that belongs to the bead and the system.
Sealant is deliberately not counted. It would need a bead cross-section and a tube volume, and that arithmetic is done properly elsewhere on the site. It is worth doing properly, because sealant volume goes with the square of the bead size rather than in a straight line: a half inch bead uses four times what a quarter inch bead uses, not twice, which is why the tube that did a whole job last time reaches half way this time.
What this page will not tell you
It does not say what thickness of glass a sash takes, whether a location needs safety glazing, what the rebate depth should be, or how a lite should be bedded. Those come from the glazing system, the glass fabricator and the code your jurisdiction has adopted, and they differ by system and by jurisdiction. Tempered glass in particular cannot be trimmed to fit after the fact, so a take-off that produces a glass size wants checking by the person making the glass before anything is ordered.
Questions people ask
How do I work out how much glazing bead to buy?
Not by dividing the total linear feet by the stock length, which is the usual method and is always low. Bead is mitred and cannot be spliced, so each piece has to come whole out of one stick and short remainders are waste rather than material. This page nests the actual pieces, longest first, into stock lengths and reports both answers side by side along with the total offcut, so you can see what the difference is worth on your own schedule.
Where do setting blocks go on a lite?
At a fraction of the daylight width in from each bottom corner, and the fraction is a specification rather than a fact. The quarter points are the figure commonly quoted, but glazing systems publish their own, and insulated units, laminated glass and long thin lites are not all handled the same way. Put the fraction your system specifies in and the page prints the position in inches for every sash width in the list.
How much does the mitre allowance change the answer?
More than it looks. Four pieces to a lite is eight cuts, so at an eighth of an inch a cut, each lite draws an extra inch of stock. On sixty lites that is five feet, which on eight foot stock is most of an extra stick. It never changes a single sash and it routinely changes a schedule, which is why the field exists and is worth setting rather than zeroing.
Why is the sealant not included?
Because it needs a bead cross-section and a tube volume, and that arithmetic is done properly on the caulk calculator, which this page links to. It is worth doing properly rather than estimating: sealant volume goes with the square of the bead size, so a half inch bead is four times the volume of a quarter inch one. Estimating from a previous job with a different bead size is how a project ends up two tubes short.
Can the take-off tell me what glass to order?
It gives you the daylight sizes you typed in and the bead around them, and stops there. What thickness a sash takes, whether the location calls for safety glazing, what the rebate depth needs to be and how the lite is bedded all come from the glazing system, the fabricator and the code your jurisdiction has adopted. Tempered glass cannot be trimmed after it is made, so the glass sizes want confirming with whoever is cutting them.