Practical guide

Set purchase, stock and sale units without losing quantities

Define box-to-each and other unit conversions, test prices and handle exceptions before importing stock.

Last materially reviewed 2026-09-24

Quick answerChoose a clear stocking unit, then document how purchasing and selling units convert into it. Test both quantities and prices; the right stock count can still hide an incorrectly priced box or pack.
What to know

Give every quantity a unit

“We have 12” is incomplete. It could mean 12 pieces, boxes, metres or sealed packs. Before choosing software fields, write the smallest unit your team needs to track and the units used by each supplier and sales channel.

Use a fictional example: a supplier sells cartons of 18 filters, the warehouse counts individual filters and customers buy packs of three. Receiving four cartons should represent 72 filters. Selling five packs should remove 15 filters, leaving 57 before other movements. Keep that arithmetic beside the sample item record and use it in the demonstration. It is an illustrative calculation, not a prescribed merchant setup.

What to know

Test price and quantity together

A correct conversion ratio does not establish a correct price. Record whether a quoted purchase price is per carton and whether a sales price is per pack. Then review a sample order total and the resulting stock movement together.

inFlow documents standard, purchasing and selling units; its guidance ties sales price to the selling unit and vendor price to the purchasing unit. It also states that serialized products cannot track units of measure. If you need both serialization and pack conversions, stop and ask the merchant to demonstrate a supported design. Do not discover that combination after loading a full catalogue.

What to know

Handle real-world exceptions deliberately

Suppliers sometimes change pack sizes. A “box” is not a reliable conversion rule unless its contents are stable and tied to the correct item or supplier arrangement. Record the actual pack definition and review incoming paperwork when it changes. Do not overwrite a ratio without understanding the effect on existing records.

For measured goods, decide how much precision you need and how partial units are handled. A business selling cable cut to length has a different problem from one selling sealed reels. Test rounding, remnants and the difference between a measured quantity and a physical package. Ask who can authorize write-offs; rounding should not become a hidden correction method.

What to know

Approve a unit matrix before migration

Create a matrix with item, stocking unit, purchase unit, purchase conversion, selling unit, selling conversion and price basis. Add a notes column for serialized items, variable-weight goods or supplier pack changes. Have both the purchaser and the warehouse operator review it.

Rehearse a receipt, a sale, a return and a count using the same item. Each participant should reach the same final quantity without translating it mentally. If the system needs separate items or a different workflow, document that decision and test its effect on reporting before proceeding. This guide explains a control method; it does not establish tax treatment, measurement compliance or support for every product configuration. Keep the approved matrix with the product master so later item additions follow the same rules.

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Next: Prepare a product master before importing inventory

Build a clean item register that distinguishes identity, purchasing, stock units and locations without importing old spreadsheet confusion.

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Sources used for this page

These records support the facts and comparisons above. Merchant-controlled records are labelled so you can separate product claims from independent evidence.

  1. inFlow units of measure — Merchant documentation · inflowinventory.com · Merchant-controlled · checked 2026-09-24