FIFO Consumption
When lot tracking is active, Partsemble consumes inventory lots in first-in, first-out (FIFO) order during builds. The oldest lots are used first. This ensures traceability, supports regulatory compliance, and gives you accurate cost tracking at the lot level.
How FIFO Works
When a build executes and needs to consume a component, Partsemble:
- Finds all active lots for that component (lots with remaining quantity > 0)
- Sorts them by received date, oldest first
- Consumes from the oldest lot until that lot is exhausted or the build's need is satisfied
- Moves to the next oldest lot if more is needed
- Continues until the full quantity is consumed
Each lot consumption is recorded individually, so you always know exactly which lots went into each build.
Example
You have three lots of 14-Gauge Steel Sheet:
| Lot | Received | Qty Remaining | Unit Cost |
|---|---|---|---|
| MS-20260301-001 | Mar 1 | 20 sheets | $34.50 |
| MS-20260315-001 | Mar 15 | 50 sheets | $35.50 |
| MS-20260401-001 | Apr 1 | 100 sheets | $36.00 |
A build requires 60 sheets of 14-Gauge Steel. FIFO consumes:
- 20 sheets from MS-20260301-001 (exhausts this lot) at $34.50
- 40 sheets from MS-20260315-001 (10 sheets remain) at $35.50
Total component cost: (20 x $34.50) + (40 x $35.50) = $690 + $1,420 = $2,110
After the build, MS-20260301-001 is exhausted, MS-20260315-001 has 10 sheets remaining, and MS-20260401-001 is untouched.
FIFO and Build Cost
Because different lots may have different costs, the actual cost of a build depends on which lots are consumed. A build that draws from cheaper older lots costs less than one that draws from more expensive newer lots.
This is reflected in the build's total cost and the finished good's weighted average cost. It's also why Partsemble shows lot allocations in the build preview — so you can see exactly which lots will be used and what the cost will be.
FIFO in Planned Builds
When you create a planned build, Partsemble pre-assigns lots using FIFO based on current stock. These pre-assignments are visible on the planned build detail page.
If stock changes between planning and execution (another build consumes some of the assigned lots), Partsemble re-evaluates at execution time and adjusts the allocations. You'll see the updated assignments in the execution preview.
Split Consumption
A single build can consume from multiple lots of the same component. And a single lot can be consumed by multiple builds. Partsemble tracks each consumption individually, so the traceability chain is always accurate.
Legacy Lots and FIFO
Legacy lots (created when receiving was first enabled) are treated as the oldest lots since they represent pre-existing stock. They're consumed first in FIFO order. As you receive new shipments and build products, legacy lots are naturally exhausted.