How do 3PLs bill for storage?

Every line of 3PL storage billing is a rate times a measure of space times a length of time. The four models differ in what they measure — and so in what the client sees as their 3PL storage fees.

Many warehouses mix them: pallet storage rates for reserve stock, bin rates for the forward pick area, and a minimum monthly charge underneath so a small account still covers its space.

A common contract reads "$X per pallet per month". The question that decides how much you collect is when you count. Count on the last day of the month and you bill for whatever happens to be on the shelf that day — a client who received forty pallets on the 2nd and shipped them out on the 28th pays for almost nothing.

The alternatives, from least to most accurate:

1. Month-end snapshot. One count, one bill. Simple, and it misses everything that came and went in between.
2. Peak or average of weekly counts. Better, still blind to mid-week movement.
3. Daily occupancy. Each location is recorded every day it holds a client's goods, and the bill is the sum of those location-days. Nothing that sat on your floor goes uncounted.

Cubic billing charges for the volume a client's inventory occupies rather than the locations it touches. It is the fairest model for mixed catalogs and the one clients most often ask for, because a pallet holding six cartons and a pallet stacked to the ceiling no longer cost the same.

It needs two things most warehouses do not have ready: the dimensions of every SKU, and the on-hand quantity each day. Volume is units times unit volume, added up across the catalog. If dimensions are missing for part of the catalog, that part bills at zero, so the first job in any cubic contract is filling in the dimensions.

Some contracts bill cubic storage weekly rather than daily — the volume on hand is measured once a week and charged at a weekly rate. That is a reasonable middle ground when daily counts are not available.

• Receiving grace period. Inventory is often free for its first few days so a client is not charged storage on goods that are still being put away. The number of days belongs in the contract and in the billing rule, not in someone's memory.
• Monthly minimum. A floor under the storage charge so a small or seasonal account still pays for the space reserved for it.
• Long-term storage. A higher rate once inventory has sat past a set age. It only works if you can tell how long each lot has been there.

Storage is rarely under-billed because the rate is wrong. It is under-billed because the count is.

• Locations that are in use but mapped to no billable storage type, so they are never counted.
• A client whose contract has storage in it but whose billing profile has no storage rate.
• Month-end snapshots that miss inventory that arrived and left inside the month.
• SKUs with no dimensions under a cubic contract.
• Grace days applied by hand, differently each month.

Each of these is invisible on the invoice — the line is simply smaller than it should be. Finding them means comparing what was stored against what was billed, location by location, which is what a margin leakage check does.

A storage clause that can be billed without argument — whatever the pallet storage rates or cubic rates are — states five things: the unit (pallet, bin, cubic foot), the rate, how often occupancy is measured, the grace period on new receipts, and the monthly minimum. To work out the rate itself from your building's cost, use the free 3PL storage cost calculator. If any one is left out, it will be decided later, on an invoice, by whoever is annoyed.

The same five things are what 3PL billing software needs to rate storage automatically: a rate per storage type, a daily record of what each client occupied, and the rules for grace and minimums applied the same way every period.