Steel Stock Lengths, Nesting, and Drops

Steel comes from the mill or service center in fixed stock lengths — typically 20, 40, and 60 feet depending on the product — and your job never needs exactly those lengths. Nesting is the process of fitting your required cuts into those stock lengths, and the leftover on each stick is the drop. The gap between what your takeoff says the job needs and what you actually have to buy is decided entirely by how well your cut list nests, which is why two shops can bid the same drawings with the same steel price and land 5% apart on material.

Your takeoff says the job contains 264 feet of W16X26. Nobody sells you 264 feet of W16X26. You buy some combination of 40s and 60s, and depending on how you combine them you'll order anywhere from 280 to 300+ feet for that same 264. That spread is real money, and it's knowable before you bid — if you nest the list instead of slapping a flat percentage on it.

Standard Mill Stock Lengths by Product

Stock lengths (mults) vary by product and by supplier. Service centers stock the common lengths; mill orders can get you others, but only at mill-order quantities with mill-order lead times. These are the lengths you can realistically count on:

| Product | Common stock lengths (ft) | Metric equivalents (m) | Notes | |---|---|---|---| | Wide-flange beams (W) | 40, 50, 60 | 12, 15, 18 | 40 and 60 are the workhorses; 50s and 65s exist regionally | | HSS (square/rect tube) | 20, 24, 40, 48 | 6, 7.5, 12 | 24s common in lighter walls; 48s from some producers | | Pipe | 21, 42 | 6.4, 12.8 | Single random (~21') and double random (~42') | | Channel (C, MC) | 20, 40, 60 | 6, 12, 18 | | | Angle | 20, 40 | 6, 12 | 20s dominate at service centers | | Flat bar / round bar | 20 | 6 | Some 12-ft in small sizes | | Plate | Sheets: 96x240, 96x480, 120x240 (in) | 2.4 x 6 m, 3 x 12 m | Nested by area, not length — different problem entirely |

Two practical points. First, ask what your service center actually stocks before you assume 60s are available — plenty of yards carry only 40s in beams below W12, and a nest built around 60s falls apart when the quote comes back all 40s. Second, metric jobs use metric mults (6 m, 12 m, 18 m); don't nest a metric cut list against imperial sticks or you'll invent phantom drops.

Nesting Basics: Fitting Cuts into Stock, with Kerf

Nesting is bin packing: your cuts are the items, the stock lengths are the bins. The standard hand method — and what most cut-list software runs — is longest-first: sort the cuts from longest to shortest, place each cut into the first stick that has room, and open a new stick when nothing fits. Sorting longest-first matters because long cuts are the hard ones to place; deal with them first and the short cuts fill in the gaps naturally.

Every cut after the first one on a stick costs you a kerf — the material the saw blade eats. Call it 1/4 inch per cut for a typical band saw. It sounds negligible until you try to get three 12-foot pieces plus two kerfs out of a 36-foot... wait, you don't have a 36. You have a 40. And that's the real lesson of kerf: it kills the "perfect" nests. Two 24-foot cuts out of a 60 does not leave you a usable 12-foot piece — it leaves you 11 feet 11-1/2 inches, which is scrap the moment your shortest remaining cut is 12'-0".

Rules of thumb when nesting by hand:

Sort descending, place greedy, then eyeball for swaps. Longest-first gets you 95% of the way; a human pass catches the last few pairings.
Budget kerf as 1/4" per cut, plus an inch or two per stick for end trim if your supplier's cuts run rough.
Pair long-and-short before short-and-short. A 19'-6" cut and a 19'-6" cut fill a 40 almost perfectly; three 12s in a 40 leave a 4-foot drop.
Watch the near-misses. A cut that misses fitting by an inch or two is a candidate for a length check back on the drawing — sometimes the detail dimension gives you that inch.

Your nest is only as good as the lengths feeding it, which is why the cut list has to come from a real bill of materials with lengths per piece, not a summary that says "8 pcs W16X26, various."

What a Drop Is Worth: Remnant vs. Scrap

The leftover on each stick is the drop, and not all drops are equal:

Scrap drop — too short to ever use (under roughly 2-3 feet for beams, less for angle and bar). Worth scrap price, maybe 10-15% of what you paid per pound.
Remnant drop — long enough to cut future pieces from (a 12-foot beam drop, an 8-foot angle drop). Worth close to full material value if you rack it, tag it, and actually check the rack before ordering the next job. Most shops don't, and the remnant quietly becomes scrap with extra steps.

For estimating, the honest position is to price drops at scrap value unless your shop has a working remnant system. If you routinely pull remnants for clips, stiffeners, and short infills, you can credit some drop value back — but be consistent, because a bid that assumes remnant recovery you don't actually practice is just a thinner margin wearing a costume.

Worked Example: One Beam List, Nested Three Ways

Take a real-shaped cut list for W16X26 (26 lb/ft) floor beams:

8 pieces @ 19'-6"
6 pieces @ 12'-0"
4 pieces @ 9'-0"

Net length needed: 264 ft (6,864 lb). Now nest it three ways, with 1/4" kerf per cut:

Nest A — 40-ft sticks only, longest first. Two 19'-6" cuts fill a 40 with a 1-foot drop (4 sticks). Three 12-footers per 40 leave 3'-11" (2 sticks). All four 9-footers fit one 40 with 3'-11" left (1 stick). Total: 7 sticks.

Nest B — 60-ft sticks only. Three 19'-6" cuts per 60 works beautifully (2 sticks, 1'-5" drops). But the leftovers fight you: the last two 19'-6" plus a 12 leave a 9-foot hole that the kerf math misses by three-quarters of an inch, and the tail end strands a 12 and three 9s on a stick with a 21-foot drop. Total: 5 sticks — fewer sticks, more steel.

Nest C — mix 40s and 60s. Two 60s take six of the 19'-6" cuts; the last two go in a 40 nearly perfectly; the 12s and 9s pack into 40s as in Nest A. Total: 6 sticks.

| Strategy | Sticks | Ordered (ft) | Ordered (lb) | Waste (ft) | Waste % | Material @ $0.55/lb | |---|---|---|---|---|---|---| | A: 40s only | 7 | 280 | 7,280 | 16 | 5.7% | $4,004 | | B: 60s only | 5 | 300 | 7,800 | 36 | 12.0% | $4,290 | | C: Mixed 40/60 | 6 | 280 | 7,280 | 16 | 5.7% | $4,004 | | Flat 10% waste factor | — | 290 | 7,550 | 26 | 10.0% | $4,153 |

Three takeaways. Nest B costs $286 more than A or C on one beam mark — multiply that across every size on the job. Nest C buys the same steel as A with one less stick to receive, handle, and saw. And the flat 10% waste factor — the estimator's default — overprices this particular list by about $150 versus the real nest. On another list it would underprice it. That's the whole argument for nesting at bid time instead of guessing.

(Also note Nest B's 21-foot drop: that's a genuine remnant, not scrap. If your shop racks remnants, B is less bad than the table shows — but only if that beam actually gets used.)

Waste Factors by Member Type: Rules of Thumb

When you can't nest — budget pricing, early-stage numbers — use waste factors that reflect how each product actually nests:

| Member type | Typical waste factor | Why | |---|---|---| | Wide-flange beams | 3-7% | Long cuts pair well into 40s/60s | | Columns | 2-5% | Often close to full mult lengths | | HSS | 5-10% | Shorter mults, more cuts per job | | Angle, channel (misc metals) | 8-12% | Many short cuts, awkward pairings | | Plate | 10-20% | 2-D nesting, connection material chews sheets |

These are starting points; your shop's history is the real answer. There's a fuller breakdown in our guide to waste factors in steel fabrication. The pattern to remember: the shorter and more varied the cuts, the higher the waste — and the more a computed nest beats a guessed percentage.

How SteelFlo's Order Sheet Builds a Nested Cut List from Your Takeoff

Everything above assumes you already have an accurate list of pieces and lengths, which is the slow part. SteelFlo generates it from the drawings: upload the PDF, the AI detects every steel member on every page (95-99% accuracy with your verification pass — you review every detection before anything is counted), and the Order Sheet tab nests the confirmed pieces into stock lengths automatically. It packs cuts longest-first with a kerf allowance, uses standard mult lengths per product — with your own stock-length overrides if your supplier only carries 40s — and shows you sticks to order, footage, and waste percentage per member size. The same data exports as a cut list or CSV for your other systems, and if you're currently doing this in a spreadsheet, compare it against our free steel takeoff template for Excel to see what the manual version costs you in time.

The takeoff-to-nest gap is where estimates quietly leak money: right count, right lengths, wrong buy. If you'd rather compute the buy than guess it, generate a nested order sheet from your next set of drawings — your first 3 takeoffs are free, and SteelFlo Pro is $399/month after that.