If you buy things and sell those same things, Shopify's inventory system is fine. If you buy things, turn them into other things, and sell those, Shopify has no idea what happened in the middle.

There is no field for a bill of materials. There is no raw material object. A candle maker with 40 SKUs and 12 fragrance oils gets 40 inventory counts and zero visibility into the oils. The oils are not products, so as far as Shopify is concerned they do not exist.

There is one native feature that comes closer than most people realize, and it is free. It is also documented well enough that you can tell exactly where it stops being useful.

What Shopify actually does: bundle inventory is derived, not stored

Shopify's product bundles documentation opens with a sentence that surprises people: "To create product bundles on your store, you must have a bundles app installed on your Shopify store." Bundles are not a checkbox in the admin. They arrive through an app — and Shopify publishes one itself.

Shopify Bundles is a free first-party app, available on all Shopify plans, that creates fixed bundles and multipacks from your existing products. The interesting part is how it counts stock.

Bundle inventory is not a number you type in. It is calculated from the components. Shopify's eligibility and considerations page gives the arithmetic: for each product in the bundle, divide that product's available inventory by the quantity the bundle needs, then take the lowest result, rounded down. Its own example: a bundle of 2 chairs and 1 desk, with 15 chairs and 8 desks in stock, is 15 ÷ 2 = 7.5 → 7 against 8 ÷ 1 = 8, so the bundle shows 7.

That is component-level deduction, running in real time, for $0. For a gift set assembled from three products you already sell, it is genuinely all you need.

There is one trap in that calculation worth knowing before you rely on it. A component's inventory is ignored entirely if the product isn't tracked, or if it is set to Continue selling when out of stock. In either case Shopify drops it from the availability math — so a bundle can keep selling on the strength of a component that ran out weeks ago.

Where it stops being a bill of materials

Everything below is from Shopify's own Shopify Bundles limitations and eligibility pages, not from merchant folklore.

Components have to be products. The whole model is products composed of other products. Half an ounce of fragrance oil is not a product with an inventory count, so it cannot be a component. To use bundles as a BOM you would have to list every raw material as a sellable product in your catalog — and then keep them out of collections, search, and feeds.

Bundles can't contain other bundles. That single line kills sub-assemblies. A finished candle made from a poured-and-cured wax blank, which is itself made from wax and oil, has no representation here.

Bundles don't support import, export, or bulk editing. With ten bundles this is an annoyance. With three hundred it is disqualifying.

A component SKU change forces a rebuild. Shopify's wording: if a component's SKU changes, "you need to delete and recreate the entire bundle."

Bundles don't track inventory by location — only overall stock. If you assemble in one warehouse and hold materials in another, the bundle count doesn't know the difference.

Bundles are incompatible with purchase options — subscriptions, pre-orders, and try-before-you-buy — and with the Shopify Subscriptions app. That rules out most subscription-box builds.

Fixed bundles cap at 30 components, dynamic bundles at 150, with up to 2,000 units per component and a maximum of 3 options and 100 variants per bundle. And the store must be on an upgraded checkout: stores still running checkout.liquid customizations are ineligible, and if a store becomes ineligible, existing fixed bundles are set to Draft and unpublished.

One inconsistency is worth flagging because it affects channel planning. The overview page says bundles can be sold through Online Store, Shop, and Shopify POS, plus Google & YouTube for fixed bundles only. The Shopify Bundles app limitations page says bundles "must use the Online Store or Headless storefronts. Other sales channels are unsupported." Both pages are current Shopify documentation. Verify against your own channels before you build a plan on either sentence.

Shopify does not pretend otherwise. Its incompatibility list says outright: for detailed component tracking, use metafields to store component SKU data "or use third-party apps for inventory management."

Four apps, four completely different meters

This is where merchants overpay. These apps all do roughly the same job — link materials to products, subtract on sale, reorder — and they charge on four unrelated units. The unit matters more than the headline price.

All figures below are from each app's Shopify App Store listing, checked September 6, 2026. All are billed in USD.

Material Manager — meters on orders per month, and nothing else

Material Manager, by Omatic, is the only one of the four whose App Store listing showed the Built for Shopify badge on September 6, 2026. Rating 4.2 from 19 reviews (15 five-star, 3 one-star). Launched December 14, 2023.

Its plan ladder varies exactly one thing after the free tier:

• Free — up to 3 materials, up to 5 variants per material, unlimited locations, up to 100 orders/month
• Standard $19.99/month — unlimited materials, unlimited locations, unlimited variants per material, low stock notifications, up to 2,000 orders/month
• Advanced $29.99/month — same, up to 7,500 orders/month
• Professional $49.99/month — same, up to 15,000 orders/month

Unlimited materials at $19.99 is the outlier in this group. A maker with 400 raw materials and 300 orders a month pays the same as one with 12 materials. The listing describes real-time sync of raw material and BOM inventory to variants, purchase order generation, forecasting, and CSV import/export, and lists Checkout and Shopify Admin under "Works with." Free plan aside, there is a 7-day free trial.

Materials Inventory — meters on materials, orders, and locations

Materials Inventory rates 5.0 from 49 reviews — 48 of them five-star, none below four. Launched January 19, 2021, developer based in Paris.

Three plans, each moving several dials at once:

• Hobby $39/month — product bundles, 500 raw materials, 500 orders/month, Shopify inventory updates
• Business $89/month — adds components, 1,500 raw materials, 2,000 orders/month, dynamic inventory alerts, custom products
• Business Pro $189/month — 6 inventory locations, 2,500 raw materials, 5,000 orders/month

7-day free trial. Note what sits behind the $89 tier: "Components" is a Business feature, not a Hobby one, and multi-location arrives only at $189. If you run two warehouses, the entry price for this app is not $39.

Craftybase — meters on order lines, which is not the same as orders

Craftybase ‑ Manufacturing ERP is the one people misread. Rating 3.6 from 19 reviews, and unusually polarized: 68% five-star, 26% one-star. Launched November 25, 2022.

• Pro $24/month ($240/year) — 1 user, 1 sales channel, import 50 order lines/month
• Studio $39/month ($390/year) — 2 users, unlimited channels, 250 order lines/month
• Indie (MRP) $79/month ($790/year) — 5 users, 1,000 order lines/month
• Business (MRP) $119/month ($1,190/year) — 5 users, 5,000 order lines/month

All tiers include unlimited materials and products, with a 14-day trial and 17% off annual.

Order lines, not orders. A customer who buys four different soaps in one checkout consumes four of your monthly allowance, not one. If your average order carries three lines, the Pro plan's 50 lines is about 17 orders a month. That is the single most misunderstood number in this comparison.

Craftybase is also the only one of the four whose listing foregrounds tax-facing financial reporting — COGS tracking, Profit & Loss, Schedule C — alongside recipes, batches and production runs. If your reason for wanting a BOM is tax and true product cost rather than stopping oversells, that focus is the differentiator.

Katana Cloud Inventory — free at 30 SKUs, then $299 and a quote

Katana Cloud Inventory is the largest of the four: 133 reviews, 4.2 average, launched March 20, 2019. It is a full cloud inventory and production platform — multi-warehouse, production scheduling, shop floor app, QuickBooks and Xero integrations, API.

Its pricing has only two published rungs:

• Free — 30 SKUs, unlimited users, unlimited integrations, API access
• Core $299/month — unlimited SKUs and users, with the listing stating that "inventory locations and sales orders are billed based on volume chosen" and that "additional paid add-ons" exist

So $299 is a floor, not a price. Two recent reviews describe what that means in practice. One US merchant, in a review dated May 5, 2026 after 16 days with the app, wrote that features they considered basic — bin locations and lot numbers — were separate paid add-ons and that the total climbed past $1,000 a month. Another, dated January 31, 2026 from a merchant who had used Katana for over five years, described the metering changing over time from users, to sales order line items, to sales orders and gross merchandise value, and concluded that a shop selling many $10 items gets pushed into tiers built for far larger businesses.

Those are two reviews, not a pattern — but they are consistent with what the listing itself says about volume-based billing, and both are worth reading in full before a trial.

The same store, four bills

Take a maker running 2,000 orders a month with roughly three items per order (6,000 order lines) and 200 raw materials, in one location:

App	Qualifying plan	Monthly cost
Material Manager	Advanced (≤7,500 orders/mo)	$29.99
Materials Inventory	Business (2,000 orders/mo, 1,500 materials)	$89
Craftybase ‑ Manufacturing ERP	No published plan reaches 6,000 order lines	not published
Katana Cloud Inventory	Core, plus volume and add-ons	$299+

Now the same store at 300 orders a month (about 900 order lines):

App	Qualifying plan	Monthly cost
Material Manager	Standard	$19.99
Materials Inventory	Hobby (≤500 orders, ≤500 materials)	$39
Craftybase ‑ Manufacturing ERP	Indie (MRP), 1,000 order lines	$79
Katana Cloud Inventory	Core, plus volume and add-ons	$299+

Roughly ten times the spread at the same order volume. Katana is a wider product than the other three — production scheduling, multi-warehouse, accounting sync — so this is not four quotes for identical work. But if all you need is "subtract the oil when the candle sells," the unit the vendor chose to count decides most of your bill.

Choosing

Your "materials" are things you already sell, and you assemble fewer than 30 of them per bundle. Use the free Shopify Bundles app. Check that every component has inventory tracking on and Continue selling when out of stock off, or the arithmetic silently ignores it.

You need real raw materials — inputs you buy but never list — and you want the cheapest correct answer. Material Manager. Unlimited materials from $19.99, Built for Shopify, and a free tier that lets you model three materials before paying anything.

You want COGS, Profit & Loss and Schedule C reporting out of the same system. Craftybase ‑ Manufacturing ERP. Before signing up, multiply your monthly orders by your average line count and check that number against the plan — not your order count.

You have multiple warehouses, production scheduling, lot numbers, or an accounting system to sync. Katana Cloud Inventory. Treat $299 as the starting point and get the add-on list in writing during the trial.

You are already at ERP scale. None of these four are the answer; that is a different evaluation.

Before you install

• Count your average order lines, not your orders. Three of the four apps meter on volume, and they do not all count the same event.
• List materials you never sell. If that list is empty, Shopify Bundles may be enough.
• Check whether you need sub-assemblies. Bundles can't nest, so anything with a work-in-progress stage rules out the native path immediately.
• Check whether decimal quantities and units of measure matter to you — grams, inches, fluid ounces. None of the four App Store listings state how fractional quantities are handled, so test it during the trial rather than assuming.
• Confirm your checkout status. If you still run checkout.liquid customizations, the native bundles path is closed to you and will draft any bundles you have.

Sources

• Product bundles — Shopify Help Center
• Shopify Bundles — Shopify Help Center
• Eligibility and considerations for using product bundles — Shopify Help Center
• Shopify Bundles — Shopify App Store
• Material Manager — Shopify App Store
• Materials Inventory — Shopify App Store
• Craftybase ‑ Manufacturing ERP — Shopify App Store
• Katana Cloud Inventory — Shopify App Store

All app pricing, ratings and review counts verified on the Shopify App Store (en-US) on September 6, 2026. App Store listings change without notice; check the listing before you install.