Shopmonkey

Inventory Costing

Structured cost tracking for parts and inventory.

RoleLead Product Designer
Timeline~4-6 months
TeamProduct Manager, Engineers, Design (me)
Year2025

Problem

Shops relied on flat or last cost values to track inventory.

This approach broke down as inventory scaled. Costs became inaccurate, margins were hard to trust, and adjustments created confusion.

There was no clear way to track how cost changed over time.

Goal

Introduce reliable cost tracking directly into inventory workflows.

  • Support multiple costing methods.
  • Improve margin accuracy.
  • Reduce manual corrections.
  • Keep workflows simple for daily use.

Core insight

Shops need accurate costs without thinking in accounting terms.

The system should handle complexity, while users interact with simple, predictable actions.

Decision + solution

We introduced structured inventory costing based on batches and cost methods.

Instead of a single cost value, inventory is tracked as a sequence of cost entries over time.

We support FIFO, LIFO, moving average, and standard cost.

Instead of a single cost value, inventory is tracked as a sequence of cost entries over time.

We support FIFO, LIFO, moving average, and standard cost.

Product UI

Focused on clarity and control.

Users interact with quantity and inventory actions, while cost logic is handled in the background. The interface surfaces only what matters: current cost, changes, and impact.

Outcome

More accurate inventory valuation.

  • Clearer margins on work orders.
  • Reduced manual corrections and errors.
  • Better alignment between inventory and accounting.

Reflection

Complex systems need simple entry points.

By separating user actions from cost logic, we made advanced costing usable without training.