How do I check a BOM before ordering PCB assembly?

Last checked 2026-11-11 against the live tool page.

Short answer

Upload your BOM (Excel, CSV, TSV or delimited text) to the free BOM checker. It looks for missing manufacturer part numbers, quantity and reference-designator mismatches, and DNP conflicts. If you also upload a placement file, it compares the two.

What you need

A BOM with a header row. Up to 5 MB or 10,000 rows.
Optional: a placement file (KiCad .pos, Altium or JLC pick-and-place, or JLC CPL). It needs one reference, X, Y, rotation in degrees and side per row.
Quantities are per board. DNP accepts yes/no, true/false, 1/0 or DNP markers. A blank cell means fitted.

What the check finds

Missing manufacturer part numbers.
Quantity and reference-designator mismatches.
DNP conflicts.
With a placement file: placements missing from the BOM, placements marked DNP, fitted BOM references with no placement data, and package-name differences.

Each finding points to the row it came from. Work through file errors first; the placement comparison only runs after those are fixed.

What the check does not do

It does not check stock or availability.
It does not verify pin 1, polarity, footprints or solderability.
A clean result means the data passed format and consistency checks. It does not mean the board will assemble correctly.
Some missing placements are expected for hand-assembled parts. THT and "Other" rows are excluded from that comparison.

Before you upload

Save formula cells as values, or make sure Excel has calculated them. Cells showing Excel errors are rejected.
Use UTF-8 or GBK/GB18030 encoding. Common delimiters (comma, semicolon, tab, pipe) work.

Nothing is saved in browser storage, and your source files are not changed.

Circuit Lab for simulation before layout.