Configurable BOM (Bill of Materials): What It Is and How It Works

Key Takeaways

• A configurable BOM (bill of materials) holds every part, option and rule for a product family. Each order resolves it into the exact parts list for that build.
• The full, unresolved structure is often called a 150% BOM. The order-specific result is the 100% BOM.
• Option lists work for simple variants. Custom dimensions need formulas that calculate quantities and cut lengths from the geometry.
• Configurable BOMs break at the handoff, when engineering rebuilds what sales already quoted. Generate both from the same source and the rebuild disappears.
• In Wabric, the quote, the BOM, the production drawing and the BIM/IFC object come from the same parametric model. Innore's railing configurator now generates BOMs, prices, drawings and ERP orders automatically, saving 80 hours of sales time a month.

What is a configurable BOM?

A configurable BOM (configurable bill of materials, or cBOM) is a single, rule-driven bill of materials for a whole product family. It contains every component the family can use. When a customer configures an order, the rules pick the parts, calculate the quantities and output the exact parts list for that build.

A regular BOM is a fixed list of the parts, sub-assemblies, raw materials and quantities needed to build a single product. That works until the product has options.

A railing range with 6 glass types, 4 mounting systems and any length the site needs doesn't have a fixed list. It has rules.

You'll also see it called a 150% BOM, super BOM (SAP's term), variant BOM, matrix BOM or dynamic BOM. Different names, same idea: a single structure that can become many products. A modular BOM is a close relative: it groups the product into selectable modules, and configurable BOMs are often organised that way underneath.

Who uses them: any manufacturer whose product changes with every order. They're standard in automotive and electronics. In construction products, they run railings and glass systems, pipes and drainage, doors and windows, prefab modules, roof and facade systems and HVAC.

What's inside a configurable BOM?

• Master structure (150% BOM): every component, module and alternative the product family can use.
• Option rules: what's compatible, what's excluded, and what a choice forces onto the rest.
• Rules engine: the logic that reads a configuration and pulls parts in or out.
• Quantity formulas: quantities, cut lengths and panel sizes calculated from the customer's dimensions. Custom-dimension products can't work without them.
• Resolved BOM (100% BOM): the exact parts list for a single order, ready for purchasing and production.

Static BOM vs configurable BOM

A static BOM describes a single product. A configurable BOM describes every product a family can become. The difference shows up in 4 places.

Scope. A static BOM lists what goes into a single variant. A configurable BOM lists everything the family can use, plus the rules for when each part applies.

Quantities. In a static BOM, quantities are fixed numbers. In a configurable BOM, they can be formulas: posts per metre of run, anchors per post, glass area per panel.

Maintenance. With static BOMs, a new bracket means editing every variant that uses it. With a configurable BOM, you change the part once and every future order picks it up.

Timing. A static BOM is written by engineering before anyone sells the product. A configurable BOM resolves the moment the customer confirms the configuration.

Sell more than a handful of variants and static BOMs become a version-control problem. Sell custom dimensions and they stop being possible at all.

150% BOM vs 100% BOM

A 150% BOM is the unresolved configurable BOM: every part the product family could ever use. It holds more than any single product needs, which is where the name comes from. The 150% is shorthand, not a real ratio.

A 100% BOM is the resolved list for a specific order. Every part, every quantity, nothing extra. It's what purchasing buys, what manufacturing builds from and what the ERP schedules.

In SAP, the 150% structure is called a super BOM, and the resolved version is the sales order BOM.

The step in between, turning the 150% into the 100%, is where the rules do their work. Here's what that looks like with numbers.

How a configurable BOM works: a glass railing example

A configurable BOM turns a handful of customer choices into a complete parts list. Take a glass balcony railing, a typical product for metal and glass systems manufacturers. The example is simplified: your real rules come from your engineering team and the building codes you sell into.

What the customer picks: 7,200 mm straight run, 1,100 mm height, base-mounted posts, 10 mm laminated glass, round stainless handrail.

What the rules do:

• Posts: maximum 1,500 mm between posts. 7,200 ÷ 1,500 = 4.8, rounded up to 5 bays, so 6 posts.
• Glass: 1 panel per bay, so 5 panels. Bays are 7,200 ÷ 5 = 1,440 mm centre to centre. Minus a 50 mm post and 2 × 10 mm clearance, each panel is 1,370 mm wide.
• Clamps: 4 per panel, so 20.
• Base plates and anchors: 1 plate per post and 4 anchors per plate, so 6 plates and 24 anchors.
• Handrail: 7,200 mm of profile from 6,000 mm stock bars. That's 2 bars, 1 cut at 1,200 mm, 1 joint connector and 2 end caps.

The resolved 100% BOM: 6 posts, 6 base plates, 24 anchors, 5 glass panels at 1,370 mm, 20 clamps, 2 handrail bars, 1 joint connector, 2 end caps. Every line carries an item code and a cost, so the price adds up from the same lines.

Now the customer changes the run to 7,350 mm. Still 5 bays, but every panel grows to 1,400 mm and the handrail cut moves to 1,350 mm. At 7,600 mm it jumps to 6 bays, 7 posts and 6 panels.

That's the part an option list can't handle. Nobody pre-writes a BOM for every length between 1 and 30 metres. The BOM has to calculate, and to calculate, it needs the geometry.

Why configurable BOMs break in spreadsheets

Most manufacturers already run a configurable BOM. It just lives in a senior engineer's head and a spreadsheet nobody else dares to touch.

Here's the usual flow. Sales quotes the request. Once the customer confirms, engineering rebuilds the parts list and draws the production drawings from scratch in CAD.

Then someone types it all into the ERP. The same order gets entered 3 times before production starts, and every retype is a chance for an error. The cost lands in the same places every time:

• Slow quotes. The customer waits while engineering checks what sales promised.
• Wrong parts. A typo in the parts list becomes a wrong cut or a missing bracket at the factory.
• Engineers stuck on revisions. Your most expensive people spend their week reworking quotes instead of engineering.
• A growth ceiling. Hiring more salespeople doesn't help when engineering is the bottleneck.
• No self-service. Customers and distributors can't configure and order online, because every order needs a person to translate it.

Krah Pipes lived this. Before its configurator, a single project could bounce up to 16 times over email before the production numbers were locked. Every sales manager priced from a private spreadsheet.

A better spreadsheet won't fix this. The fix is generating the quote and the BOM from the same source, so there's nothing left to rebuild.

Where should configurable BOM rules live: CPQ, ERP or PLM?

Put the rules where the customer configures. That's usually the CPQ, because ERP and PLM only see the order after it's sold. Each system still owns its own version of the BOM.

PLM and CAD own the engineering BOM (EBOM): the product as designed, with part numbers, revisions and drawings.

ERP owns the manufacturing BOM (MBOM): the product as built, with routings, stock and purchasing. Once an order exists, the ERP runs procurement and scheduling.

CPQ owns the configuration rules: what the customer can choose, what's compatible, and how quantities and prices are calculated. It resolves the configurable BOM into a 100% BOM per order and hands it to the ERP.

The trap is splitting the rules. Compatibility sits in the CPQ, quantity formulas in a spreadsheet, item codes in the ERP. Each copy drifts, and the quote stops matching what gets built.

Keep the rules in a single place and send finished orders to the ERP through an integration.

Comparing tools for this? Here's our breakdown of the best CPQ software for manufacturing.

How Wabric builds the BOM from the product model

Rules-engine CPQ tools resolve the BOM from a rules table and leave the geometry to a separate CAD system. Wabric resolves it from a parametric 3D model of your product, the same model that produces the quote, the production drawing and the BIM object.

Your customer configures in the browser. What they're changing is a digital twin with real geometry, real constraints and your engineering rules. When they confirm, the same model produces:

• A priced quote with a live, itemised BOM
• Production-ready drawings (DWG) for CAM, sheet metal and CNC
• An IFC/BIM object for the architect's Revit, Archicad or Tekla model
• A structured data record with identifier, attributes, materials and classifications, the data an EU Digital Product Passport draws on

These are projections of the same model, so they can't disagree. The BOM matches the drawing, the drawing matches the quote, and nobody redraws anything after the order is confirmed.

This is what we mean by BIM-powered CPQ. The model that prices the order also produces the IFC object, so your product lands in the architect's model at the right size, at the moment it gets specified.

The rules sit in Wabric PIM: compatibility, pricing logic, classifications and certifications. CPQ runs them, and the resolved BOM goes to your ERP. Most of the team behind Wabric are engineers, so your rules get modelled by people who read production drawings for a living.

Here's what that looks like in practice (customer stories):

• Innore's balcony railing configurator generates BOMs, prices, drawings and ERP orders automatically. It saves 80 hours of sales time a month and has cut 50% of manual quoting.
• Krah Pipes moved up to 80% of technical drawings and revisions from engineering to sales and partners, with 100% pricing consistency.
• R-Fix runs automated CPQ with live ERP pricing and saves hundreds of engineering hours per month.
• Wallenium quotes custom-dimension rooms in real time, with an instant order PDF and 3D snapshots.

Want to see this on a product like yours? Book a demo and we'll walk through which modules fit. Book a demo →

How to set up a configurable BOM in 6 steps

A configurable BOM is mostly a data and rules project, not a software project. Here's the order we'd follow.

Step 1: Map what the customer can change

List every option, dimension, material and finish. Mark which are choices from a list and which are free values like length or angle, because free values need formulas.

Step 2: Clean up the parts list

Collect every component the family uses, with item codes that match your ERP. Fix duplicate codes and parts with no code now. Each one becomes a manual step later.

Step 3: Write the rules with engineering in the room

Inclusion rules (this handrail needs that bracket), exclusion rules (this glass doesn't fit that clamp), quantity formulas (a post every 1,500 mm) and limits (maximum span, minimum height). Many of these live only in senior engineers' heads, so get them written down. In SAP, inclusion rules are called selection conditions.

Step 4: Price from the BOM lines

Build the price from the resolved lines: material, labour, margin rules and surcharges. The price then moves whenever the BOM moves, and nobody quotes from memory.

Step 5: Test against orders you've already built

Run 20 to 30 past orders through the rules and compare the output with what you actually delivered. Every mismatch is a missing or wrong rule.

Step 6: Give the rules an owner

Products change. Name a person who owns rule changes, version every release, and treat a rule change like an engineering change.

Summary

A configurable BOM holds every part and rule for a product family and resolves each order into the exact 100% BOM. Option lists cover simple variants. Custom dimensions need formulas tied to geometry.

The usual failure point is the handoff: sales quotes, engineering rebuilds, someone retypes it all into the ERP. Keep the rules in a single place and generate the quote and the BOM from the same source.

Wabric goes a step further. The quote, the BOM, the DWG drawing and the BIM/IFC object all come from the same parametric model. Every quote, ready to build.

Book a demo to talk through your product and which Wabric modules fit. Book a demo →