The multiplication nobody does
Four inches off each end of a 10 ft board is eight inches, which is 6.7 percent of the length. On the defaults — 8 in wide, 1-1/16 rough, 500 boards making 3,542 board feet — that is 236 board feet on the floor, and at $3.40 it is $803. Per thousand board feet it is $227, which is more than most people would guess and considerably more than the sealer.
The reason it hides is that the loss arrives one board at a time, at the crosscut saw, weeks after the drying, and it never appears on any tally as a line item. It is simply the difference between the length you sawed and the length you sold.
End grain area is small and the cost of covering it is small
The same 500 boards have 1,000 ends, each 8 by 1-1/16 inches, which is 59 square feet in total. At 200 square feet per gallon and two coats that is 0.59 gallons — under $23 of sealer at $38. Add $90 of labour and sealing the lot costs $112, against $803 of trim if none of it were needed.
That asymmetry is the whole reason end sealing is standard practice at mills that dry their own stock. It is not that sealing is cheap in absolute terms, it is that end grain is a tiny fraction of a board's surface area while the ends are a substantial fraction of its length.
Break even in inches, not dollars
The useful form of the question is: how much trim does sealing have to save before it pays? Divide the sealing cost by the value per board foot and by the cross-sectional area of all the ends, and on the defaults it comes to 0.56 in an end. Sealing has to save nine sixteenths of an inch off each end to break even. Whether it does is a question about your species, your climate and your sealer, and this page does not answer it — but nine sixteenths against the two and a half inches in the defaults is a wide enough margin that it is worth measuring rather than arguing.
Minimum length is the hidden cliff
Trim is a smooth loss until it crosses a length the market cares about. A 10 ft board trimmed to 9 ft 4 in is worth slightly less than a 10 ft board. A 8 ft 6 in board trimmed to 7 ft 10 in has stopped being an 8 ft board, and the loss is not the six inches, it is the whole difference between two products. The minimum length field is there to flag that boundary, because it is where the money in trim loss actually concentrates.
Questions people ask
Where do I get the sealed trim figure if I have never sealed anything?
You measure it, and until you have it the comparison block is guesswork. Seal one end of every board in a pack and leave the other bare, dry it as usual, and trim both ends to the same standard — same person, same rule about what counts as a check. The difference between the two piles of offcuts is your figure, for your species at your thickness in your climate, and it is worth more than any published number.
Does the calculator assume sealing works?
No. It takes two trim lengths you supply and prices the difference between them, and it will happily report that sealing loses money if that is what your two figures say. If you enter the same trim for sealed and unsealed, the saving is zero and the whole sealing cost shows as a loss, which is the correct answer to that input.
Why is the trim measured in sixteenths?
Because that is the resolution the answer lives at. The break-even is often a fifth or a quarter of an inch, and rounding the trim comparison to the nearest tenth of an inch would either erase the difference or invent one. Anything you can actually measure with a rule at the crosscut saw is worth showing at that resolution.
Should I count trim on both ends?
That depends on how the boards were handled. Both ends are exposed on a stack in the open, so both usually check, and the default is both. If one end was buried in a pile, was cut later, or was already sealed by whoever supplied the log, set the field to one end and the arithmetic halves accordingly — both the trim and the sealer.
Does this cover the checks that run into the middle of a board?
No. This is a length arithmetic: you cut a fixed distance off and count what you lost. A check that runs a foot up a board past where you were prepared to trim is a grade problem, not a trim problem, and it belongs on the degrade and cull page instead. Keeping the two accounts separate is the point, because they are fixed by different things.