Prophet 21’s Base Unit of Measure (UOM)

The topic we want to talk about today is setting up Unit of Measure for items in Prophet 21.

Prophet 21’s Base Unit of Measure

The first thing to understand is that the base unit of measure is how inventory will be stored in the database. It’s the lowest functional unit of inventory. My guidance in 99% of situations is that it should be the lowest conceivable unit that you will operate in. Notice I didn’t say sell by. I avoided those two words on purpose.

Here’s a great example: We buy this item by the palette and sell it by the box. However, we also do secondary processes to break it down. We put it into smaller packages for vending machines.

So the question is what is the smallest conceivable unit you will try to transact in?

In this example, most times we will sell a pack of twelve—that’s the base unit. But if we ever crack that package open, we are now working in units of EACH.

Your smallest one doesn’t have to be what you sell. If you always sell them in packs of twelve, you make that your default sales unit.

Unit of Measure Checkboxes

So the checkboxes that you’re faced with are the default sales and sales pricing unit.

Default Sales

By default, if I enter a sales order for this, it will be for one of that unit or x of that unit. This could be a case, a carton, a box, or an EACH. It doesn’t matter. Go with whatever you normally sell the product in.

Sales Pricing Unit

You may ask, why would default sales ever be different than the sales unit? Well, some industries do that. If you take the fastener industry, for example, you frequently get into situations where things are so small and inexpensive that even tenths of a penny count.

To combat that, they sell items by the hundred or by the thousand. So you’ll see a pricing unit of C or M (Roman numerals). For example, I sell you five hundred items priced at five dollars per hundred. Or fifty dollars per thousand. How do you want to set that up?

Purchase pricing and purchase units are the same thing. It’s just on the buying side. If they normally sell by the box, but we buy by the case or the palette or whatever, this allows you to do that.

Substituting Item Suppliers

Now, if you substitute a lot, and you’re substituting similar products from different suppliers you need to be extra careful with your base unit of measure.

For Example: Bic sells pens in packs of twelve. Paper Mate sells them in packs of ten. If you have those set up as substitutes, you need to remember that if a pack is your base unit for those two things, it doesn’t represent the same number of pens. You subbed ten pens for something you would normally sell twelve.

That’s a bad example, but if you’re trying to know how many pens you sold, your substitution will be messed up because it will try to default back to the base unit. But if the two base units are not common to each other the data is worthless.

So, these are considerations if you manufacture, or if you do a lot of production.

Here’s another good real-life example. Let’s say that you’re making bolts out of bars of steel. You’re making a four-inch bolt out of a forty-foot bar of steel. So you can only make a certain number of bolts from one bar. If the base unit of measure for the steel is one bar, you would have to divide it to 1/480th of a bar to get to an inch. And doing that will get you into decimal precision issues that will haunt you for the rest of your days. And decimals are so much fun in P21 (sarcasm).

So in manufacturing, we may always buy by the bar, the pound, the hundredweight, or whatever it is. But if we’re cutting it down to an inch or smaller, we need to set that base unit to measure at the smallest unit that we could conceivably work in.

Unit of Measure Rule of Thumb

Remember, it’s easier to go up than to come down.

So if you’re struggling to decide on your organization’s base unit of measure, err on the side of using a smaller unit of measure. It’s much easier to convert up than it is to convert down.

If you need to convert up, you simply set a different unit of measure as your default and be done with it.

If you need to convert down, you have to do a base unit of measure change. And I will tell you straight out. I have never been that successful in doing those unless I canceled the sales orders, canceled the POs, and adjusted all the amounts, essentially canceling four transactions.

Changing Units of Measure in Prophet 21

As a team, we have tried to do it the other way. We tried to do it midstream.

We basically would cancel all open transactions. First, we would adjust out and go create the new unit of measure. Next, we would soft delete the old unit of measure, then go back and adjust with the correct end value. It’s the only way to do it a hundred percent right.

But, honestly, your best bet is to burn it down and then rebuild it back up. Again, seriously, err on the side of setting your base smaller because it’s way easier to recover from a smaller base unit of measure.

This is why unit of measure should not be a default in item maintenance. Because it gets nasty real quick. We have seen systems set up where each case in a pack all have a unit size of one. That doesn’t work. That’s not how math works.

In a pre-implementation consulting scenario, we will spend more time talking about how you will set up the intricacies of items than anything else because Prophet 21 is a distribution system. Of course items underpin everything. That’s what distribution is. And trying to unravel fundamental mistakes in that process is incredibly difficult.

As a consulting team, we have done it. We’ve gone in and repaired 75,000 items, but it is complicated, time-consuming, and definitely not something we recommend.

Conclusion

Prophet 21’s Unit of Measure is one of those things that touches everything you do in your business, but sometimes people just pencil-whip it through. It’s so important why would you not take the time to make sure it’s right?

Continue Learning: How to set Units of Measure in Prophet 21.