Reselling storage cost calculator.

Worked example

A $150-a-month unit holds 300 items, each earning a $12 margin and sitting about three months. Rent is $150 ÷ 300 = $0.50 per item per month, $1.50 over the three months, which leaves $10.50 of the $12. Break-even stock is $150 × 3 ÷ $12 = 37.5, so 38 items. With 300 items the unit uses a small share of its margin; with 20 items it would not cover itself. If your items instead sit nine months, break-even stock triples to about 113, because each item pays rent for longer.

How the model works

Methodology. Rent per item per month = rent ÷ items stored. Rent per item held = that × average months held. Margin per month held = margin ÷ months held, and break-even stock = rent ÷ margin per month held (rounded up). Steady-state monthly profit = (items ÷ months held) × margin − rent, which assumes the unit stays full and turns once per average hold time. FBA: units × cubic feet × the monthly rate per cubic foot you enter, plus aged units × cubic feet × the aged surcharge rate you enter.

The page deliberately stores no Amazon rate, because FBA storage fees change by month and size tier. Read them on Amazon’s page, or use the FBA monthly storage fee calculator and the aged inventory surcharge calculator, then enter the per-cubic-foot numbers here.

Home space versus a unit

Free space has a cost too: a room you could use otherwise, or inventory that stops you parking. A unit makes the cost visible, which is useful for deciding. Compare the rent per item against the margin and against the cost of holding a slow item, and check turnover with the days of inventory and carrying cost tools.

How to use it well

Use realistic hold times from your own sales history rather than the time you hope items will take; slow items dominate the rent. If the result says you are below break-even stock, there are three levers in the formula: a smaller or cheaper unit, a higher margin per item, or a shorter hold time. Try each separately. For Amazon inventory, copy the current per-cubic-foot fee and aged surcharge from Amazon’s own pages into the optional section, since both change through the year, and compare the per-unit cost with the profit per unit you expect.

What this tool does not cover

• Insurance, deposits, climate control, access hours, lock costs and time spent travelling to the unit; add them to rent.
• Whether storage rates in your area are high or low. You enter the rent.
• Any Amazon rate or surcharge threshold; enter your own from the Amazon page.
• Tax treatment of rent. General information only; see the IRS pages cited.
• Mixed margins. The page uses one average margin.

Sources (retrieved October 2026)

• Amazon Seller Central: monthly inventory storage fees: where the FBA storage rate per cubic foot is published. Retrieved October 2026. This page does not store any Amazon rate; you enter it.
• IRS About Schedule C (Form 1040): how self-employed sellers report profit or loss. Retrieved October 2026.

Every other number on this page is an input you type or an assumption labelled as an example. Results vary, and nothing here is an income claim.

FAQ

Is a storage unit worth it for reselling?

It is worth it when the stock inside earns more margin than the unit costs. The break-even stock level shows how many items that takes at your hold time and margin.

How many items do I need to cover a storage unit?

Rent × months held ÷ margin per item, rounded up, items in the unit at once, under the assumption that items sell after the average hold time you enter.

What is the cost of storage per item?

Rent divided by items stored gives the monthly cost per item; multiply by months held for the cost over an item’s life.

How do I include FBA storage?

Enter units, cubic feet per unit and the monthly fee per cubic foot from Amazon, plus the share of aged units and the aged surcharge rate.

Does faster turnover change the answer?

Yes. Shorter holds mean each item pays less rent, so break-even stock falls in proportion.