3PL storage fees explained: how the cube is measured and billed.

3PL storage fees are the monthly charge for the space your inventory takes up in the warehouse, billed per pallet, per bin or shelf, or per cubic foot. The unit decides the bill more than the rate does: per pallet and per bin charge for a position whether it is full or nearly empty, while per cubic foot charges for the volume your stock actually occupies. To know what you will pay, measure your cube from your carton dimensions, then ask when and how the warehouse measures it.

Per pallet, per bin, per cubic foot: what each unit charges for

A pallet position is a footprint and a height. The common footprint is 48 by 40 inches, the size USPS specifies for palletized mail as of October 2026. Say your pallets are stacked 48 inches high on that footprint: 92,160 cubic inches, or about 53 cubic feet when the pallet is full. Per pallet billing charges for the position, not the contents. A pallet that is a quarter full after a good run of sales costs the same as the day it arrived.

Per bin or per shelf is the same structure at a smaller size. It suits small goods, jewelry for example, because a bin holds a lot of units. The trap is the same as the pallet. Say ten SKUs each have a few units left: that is ten bins on the bill.

Per cubic foot charges for the volume the stock occupies, measured from the SKUs on the shelf. When stock sells down, the cube falls and the bill follows it. It rewards fast turns, and it is where the measuring rules matter most, because the warehouse decides what counts as a cubic foot and when it is counted. The rest of this guide is about that measurement. For the other lines on a quote, handling, receiving, returns and postage, read 3PL pricing line by line.

How to measure your inventory cube from carton dimensions

You can measure your cube before you talk to any 3PL, from the SKU list, the master carton dimensions from your supplier or your last inbound, and the on-hand count. This is the sequence we run on the floor.

1. 01List every SKU with its units per master carton and the carton's length, width and height in inches. Measure the carton as packed, not the bare product, because the carton is what sits on the shelf until it is broken down.
2. 02Multiply length by width by height for each carton. That is the carton's volume in cubic inches.
3. 03Divide by 1,728, the number of cubic inches in a cubic foot per NIST Handbook 44, as of October 2026. Say a carton is 16 by 12 by 10 inches: 1,920 cubic inches, or about 1.11 cubic feet.
4. 04Divide the carton cube by the units per carton to get the cube per unit, and keep it in the SKU list next to the weight. You will need the same column when you send inventory to a 3PL and when you compare quotes.
5. 05Multiply the cube per unit by the on-hand count of each SKU, then add the SKUs up. Say that SKU has 90 unopened cartons on hand: 100 cubic feet. The total across SKUs is your cube today.
6. 06Run the total again for the day after your next inbound lands and the day before it. Both numbers are true. Which one you pay for depends on the measurement rule, covered next.
7. 07Add anything else the warehouse will hold for you: branded boxes, mailers and inserts, and returns waiting to be graded. They take space, and some quotes count them.

Put the cube per SKU in the same file as your weights and your last three months of orders, and ask every 3PL to price that file rather than a round number. To see how storage sits next to handling and returns, fulfillment cost per order works a month through at our estimated rates.

Why your cube falls as you sell through, and why the measurement date matters

Inventory does not sit at one level. A container lands and the cube jumps. It falls every day as orders ship. Then the next inbound lands. On a chart it is a sawtooth, and a storage bill has to pick a point on that sawtooth or average it. That choice changes the invoice more than a few cents on the rate does.

Say your stock stands at 400 cubic feet on the first day of the month and sells down evenly to 200 cubic feet by the last day. This is the same month at our estimated $0.65 per cubic foot, measured on different rules.

Same stock, same rate, and the first bill is twice the last one. A snapshot taken right after your inbound bills the peak for the whole month. A daily average bills what you occupied. Neither rule is wrong if it is written down, which is why the questions later in this guide start with the date. For a stated rule, Amazon charges FBA storage monthly on the daily average volume in cubic feet, as of October 2026.

Why slow SKUs cost more to store than fast ones

Storage is billed by the month but paid by the unit sold. The storage a unit carries is its cube, times the rate, times the months it waited on the shelf. Say two SKUs arrive at the same cube, and one sells out in a month while the other takes ten months: the slow one puts about ten times the storage cost into each unit it sells.

The second effect is quieter. Slow SKUs do not sell down, so their cube never falls. They hold the bottom of the sawtooth up, and the daily average that helps on fast SKUs does nothing for them. Amazon puts a fee on this: FBA charges an aged inventory fee monthly on items stored for more than 181 days, as of October 2026. A 3PL quote can carry a similar long-term storage line. Ask for it by name.

The fix is merchandising, not a different rate. Watch sell-through by SKU, size and color, and treat a SKU that has not moved in a season as a decision: mark it down, bundle it, move it to a channel that sells it, or dispose of it. Bring deep SKUs in on smaller, more frequent inbounds so each peak of the sawtooth is lower. When you compare quotes, price slow SKUs on their own: on a per-pallet quote, a slow SKU that fills a quarter of a pallet costs the whole position for as long as it sits. The hidden 3PL fees checklist covers the long-term storage line and where it hides.

What to ask about when and how the cube is measured

Every per cubic foot rate hides a measuring rule. Get these answers in writing before you compare the number to anyone else's.

• When is the cube measured: a snapshot on a set day, the peak during the month, or a daily average? If it is a snapshot, which day, and does it fall right after your usual inbound?
• What is measured: the units in the bin, the master carton as received, or the location the stock sits in? A location rule rounds a half-empty bin or pallet up to a full one.
• When are dimensions taken: at receiving from the carton, or again when cartons are broken down into bins? Can you see the dimensions on file for each SKU and correct them?
• Is storage prorated when stock lands or leaves mid-month, or does a pallet that arrives on the last day bill for the whole month?
• Does the storage rate change for the holiday season, and is there a long-term storage line after a set number of days?
• Do returns waiting to be graded, packaging materials, and quarantined or damaged stock count in the cube, and at what rate?
• Can you see the cube by SKU in the dashboard, so the invoice can be checked against it without a phone call?
• When the count on the invoice disagrees with the count on the shelf, who recounts, and when is the invoice corrected?

Storage on our floor at YNK

Storage at YNK is an estimated $0.65 per cubic foot per month, billed on the space you actually use. It is invoiced monthly, on the same invoice as handling. There are no seasonal or peak surcharges on handling or storage: your rate in December is your rate in June. There is no setup fee. Receiving is billed hourly and packaging and supplies are billed as used, each on its own line, so the storage line is storage and nothing else. Your exact rates are confirmed in your quote once we see your volume and profile.

The cube starts at receiving, which is scan-to-stock. Every unit is scanned against the SKU list, counted and shelved, so look-alike sizes and shades never share a bin, and cycle counts keep the count on your dashboard equal to the count on the shelf. The dashboard is the one we run our own brands on, with live inventory by SKU, sell-through, size and color velocity, and reorder triggers, so a SKU that has stopped moving shows up before it has sat for a season. Supplements, gummies, beverage and food-grade goods are received by lot with expiry dates and picked first-expired-first-out, so the oldest sellable stock ships first. Climate-controlled storage is available, with the specifics set case by case in your proposal. Branded boxes, mailers and inserts you send are stored and packed to your spec.

To get the storage line priced on your own cube, send the 3PL intake. It takes about ten minutes and asks for your SKU list with sizes and weights, the list you built in the steps above, plus your last three months of shipments. An operator replies within one business day, and the proposal follows within five with your exact rates. Inventory ships to 465 Mola Blvd, Dock 10, Elmwood Park, NJ 07407. To try the math first, put your own numbers into the cost calculator.

Questions founders ask about storage fees