Cut list optimizer vs. planning cuts by hand
Cutting a job list top to bottom, one part type at a time, gets every individual length right. What it doesn't do is hold a cut back from an early part type to pair it with a complementary length from a later one -- and that pairing, not the arithmetic on any one cut, is what decides how many boards the job actually needs.
What a hand plan gets right, and what it doesn't
| Planning by hand, part type by part type | This optimizer | |
|---|---|---|
| Each cut's own length | Correct, if measured carefully | Correct, from the same list |
| Pairing across part types | Not considered -- a board closed out while cutting one part is not reopened for a later part | Holds every board open until nothing left in the list fits it |
| Boards kept in progress at once | Effectively one -- finish a part, close its boards, move on | As many as the list needs, tracked automatically |
| Offcuts already on the rack | A separate mental note, easy to forget mid-job | Placed into before any new board counts as bought |
Same 24 parts, two plans
Take a face-frame job: 6 stiles at 22", 8 rails at 34", 6 aprons at 46", and 4 legs at 58", cut from 8-foot (96") stock with a 1/8" kerf at $42 a board. Cutting the ticket the way it's usually written -- all 6 stiles first, then all 8 rails, then the aprons, then the legs -- books:
| Boards booked | 13 |
|---|---|
| Utilization | 73.1% |
| Waste (length not cut, net of kerf) | 334.63" |
| Cost at $42/board | $546.00 |
The same 24 parts, planned by holding every board open until nothing left in the list fits it, book onto 10 boards: three rail-and-leg pairs (58"+34"), three rail pairs with an apron (46"+46"), a rail-stile-apron mix (46"+34"), two stile-and-rail combinations (34"+34"+22"), and one board of stiles alone (22"x4):
| Boards booked | 10 |
|---|---|
| Utilization | 95.0% |
| Waste (length not cut, net of kerf) | 46.25" |
| Cost at $42/board | $420.00 |
Three fewer boards, $126 not spent, on a list where every measurement was correct either way. The difference is entirely which board each cut lands on -- specifically, that a 58" leg and a 34" rail (92" together) share a 96" board with only the kerf between them, a pairing a part-by-part read-through never has reason to try because the rails haven't come up yet when the legs are being cut.
Why the gap grows with the list, not the mistakes on it
Nothing about the hand plan above was careless -- every cut was measured and placed correctly onto a board that fit it. The gap comes from having only one part type open on the saw at a time, so a board with room left over when a part type finishes is closed out rather than held for a length that hasn't come up yet. A longer, more varied list gives this more chances to happen, not fewer: the more distinct lengths a job has, the more complementary pairs exist to miss by cutting in ticket order.
Open the Cut List Optimizer to plan your own list against the boards or offcuts you actually have. Comparing sheet sizes instead of board lengths? See 4×8 vs 5×5 sheets. Weighing this against a hosted optimizer? See this cut list optimizer vs. optiCutter and CutList Optimizer.
Common questions
What does planning cuts by hand usually get right, and what does it miss?
Cutting a job list top to bottom, one part type at a time, gets every individual cut right -- the lengths are correct and nothing is wasted through error. What it doesn't do is hold a cut back from one part type to pair it with a complementary length from a different part type later in the list, because by the time that later, shorter part comes up, the board it could have shared has usually already been closed out and set aside. That pairing is exactly what determines how many boards the job actually needs.
Why does cutting by part type use more boards than the same list needs?
Because a job ticket is naturally grouped by part -- all the stiles, then all the rails, then the aprons, then the legs -- and a board closed out while cutting stiles is not reopened once rails come up, even if a rail would have fit in the space left over. Holding it open across part types means keeping several boards in progress on the saw at once, which is exactly the bookkeeping a hand plan skips in favor of finishing one part before starting the next.
How big is the gap in practice?
On a 24-part face-frame list -- 6 stiles at 22 in, 8 rails at 34 in, 6 aprons at 46 in, 4 legs at 58 in, cut from 96 in stock with a 1/8 in kerf -- cutting each part type in order books 13 boards at 73.1% utilization. This optimizer's plan for the identical list books 10 boards at 95.0% utilization: 3 fewer boards, worth $126 at $42 a board, entirely from which board a cut lands on, with no part mismeasured either way.
Does this optimizer know my local lumber prices?
No. It has no data on what your yard charges. It takes your cut list, your stock length, your kerf, and the price you enter for a board, and turns that into a plan and a cost -- the packing arithmetic a hand plan skips, not a price lookup.