How to write a parts list that suppliers can actually quote (and deliver correctly)

Ask a distributor’s sales engineer what slows down a quote and you will not hear “price”. You will hear about the list. A photo of a handwritten sheet. A part number with a letter O where a zero should be. “Bearing for the big motor, the usual one.” Twelve lines where the manufacturer column says “Siemens or similar” and nobody knows what similar means.

Every one of those costs a day. The sales engineer emails back a question, the purchasing manager forwards it to maintenance, maintenance is on the floor, and the quote that should have taken an hour arrives on Thursday. Worse, the ones that do not trigger a question are the ones that go wrong. The supplier guesses, quotes something close, and the box that arrives is not the part that was needed.

This is a guide to writing a parts list that does not need a follow up question. It takes ten minutes more at the start and saves days at the end.

The five columns every line needs

A quotable parts list has five things per line: the manufacturer, the manufacturer part number, a short description, the quantity, and the unit. Everything else is optional.

The manufacturer is the company whose name is on the part, not the distributor you last bought it from. “Schneider Electric”, not “the electrical wholesaler on the ring road”.

The manufacturer part number, often called the MPN, is the code the manufacturer prints on the part and lists in its catalogue. It is the only field a supplier can search without guessing. A good part number search on the supplier side takes seconds. A description search takes a phone call.

The description is there for a human to sanity check the number. “Contactor 9A AC-3, 24V DC coil” next to LC1D09BD lets the sales engineer spot a mismatch. It should be short and it should never replace the number.

Quantity and unit sound obvious until someone orders 1 of a cable that comes in 100 metre drums, or 50 of a terminal sold in strips of 10. State the unit you mean.

Where the part number comes from

The number is on the part, on the nameplate, or in the machine documentation. In that order of convenience and reverse order of reliability.

Take bearings, which cause more wrong deliveries than almost anything else. If you are wondering how to find bearing number when the ring has worn smooth, start with a calliper. Measure the bore, the outer diameter and the width in millimetres, then run a bearing number lookup in any manufacturer’s catalogue. Three dimensions normally return one or two candidates. Then check the machine manual for the suffix, because 6205 and 6205 2RS C3 have the same dimensions and are not the same part. Put the full designation on the list, suffix included.

For electrical parts, the number on the front of the device is usually the complete order code. Copy it exactly as printed. Do not shorten LC1D09BD to LC1D09, because the last two letters are the coil voltage and without them the supplier has to ask.

For anything inside a machine, the OEM parts list in the manual is the best source. It will give the OEM’s own number and, very often, the original manufacturer’s number underneath. Put both numbers on the list.

Put the engineering decision on the list, not the engineering question

A parts list is not the place to work out what to buy. It is the place to record what was decided.

Suppliers regularly receive lines like “VFD for 7.5 kW pump” or “contactor suitable for 11 kW motor”. That is a design question dressed as an order. The engineer knows how to choose contactor for motor duty and how to choose vfd for motor loads. The vfd sizing has been done against the motor’s rated current, and the pump curve has been checked for vfd sizing for pumps. The list should carry the result of that work: a specific drive with a specific order code, and a specific contactor with its coil voltage and a matching motor protection relay range. If the decision has not been made, make it before sending the list, or mark the line clearly as “please propose” so it is not quoted as if it were final.

The same goes for equivalents. If ABB instead of Schneider is acceptable on a line, say so on that line. If it is not, say nothing and expect the exact part. A supplier who quotes an equivalent without being told either way has guessed, and you will not find out which lines were guessed until the delivery.

Common mistakes and what they cost

The transposed digit. 6205 becomes 6250. 3RT2016 becomes 3RT2061. The supplier either quotes the wrong part or, if the number does not exist, stops and asks. Both outcomes cost a day at minimum, and the first one costs a return.

The letter O and the zero. In most fonts they are hard to tell apart, and part numbers mix letters and digits freely. Type the list, do not photograph it, and if you must handwrite, put a slash through zeros.

The missing suffix. Coil voltage on contactors. Seal and clearance codes on bearings. Cable length on pre made cables. Enclosure rating on sensors. The base number gets you the family; the suffix gets you the part.

The distributor’s internal code. Every large distributor assigns its own stock number to every part. That number means nothing to any other supplier. If you copy it from an old invoice into a list that goes to three distributors, two of them cannot use it.

The “as before” line. “Same as last order” only works with the supplier who took the last order, and only if they still have it on file. Write the number.

Mixed units of quantity. Metres, pieces, packs, drums. Be explicit on every line, not just the first.

A layout that works in Excel

A simple bill of materials template excel users can build in two minutes has these columns, left to right: line number, manufacturer, manufacturer part number, description, quantity, unit, and a notes column for “equivalent acceptable” or “urgent”. Keep one part per row. Do not merge cells. Do not put two quantities in one cell because “we might want more”.

Freeze the header row, sort by manufacturer so the supplier can see at a glance which lines are theirs, and save it as a spreadsheet, not as a PDF. A PDF has to be retyped at the other end, and every retyping is another chance for a wrong digit.

If you have a longer list, add a column for the machine or location the part is for. It does not help the supplier, but it helps you when the boxes arrive and someone asks which line was for which conveyor.

Check the list before it leaves

A two minute check before sending catches most of the errors above. Read each part number against the catalogue or against the nameplate photo. Confirm that every line has a manufacturer. Confirm that every quantity has a unit. Look for any line that describes a requirement rather than a part, and either resolve it or mark it.

If you send lists regularly, keep a master sheet of the parts you buy repeatedly, with the full manufacturer numbers verified once. New lists are then copied from that sheet, and the checking happens once instead of every time.

Where PartM8 fits

PartM8 was built on the idea that the list is where orders go right or wrong. You fill in a parts list template with exactly the columns above, or type part numbers in directly with catalogue autocomplete, and every line is checked against a parts database before any supplier sees it. A malformed number is flagged with a suggested correction and you decide whether to accept it. Nothing is corrected without you seeing it. Then the list goes to suppliers whose catalogue actually matches the lines, and one offer comes back within 24 hours with each line priced with delivery included and the supplier named. The ten minutes you spend on the list still matter, but the transposed digit no longer gets as far as a delivery.

Frequently asked questions

What should a parts list include for a supplier quote? At minimum: manufacturer, manufacturer part number, a short description, quantity and unit for every line. Add a note where an equivalent brand is acceptable. Send it as a spreadsheet, not a PDF or photo.

How do I find a bearing number if it has worn off? Measure the bore, outer diameter and width in millimetres and search a bearing catalogue with the three dimensions. Check the machine manual for the suffix, such as 2RS or C3, and write the full designation on the list.

Should I put “Siemens or equivalent” on my parts list? Only if you actually accept an equivalent on that line, and only if you are prepared to check what the supplier proposes. Otherwise write the exact part and expect the exact part.

Can I send a distributor’s own stock number instead of the manufacturer number? Not if the list goes to more than one supplier. Distributor stock numbers are internal to that distributor. The manufacturer part number is the one every supplier can search.