$0.78 a cubic foot in March. $2.40 a cubic foot in November. Same box, three times the cost. Storage is the fee sellers notice last and regret hardest — it is invisible on a single unit, and brutal across 1,000 slow ones.
| Product size | Off-peak (Jan 15 – Oct 14) | Peak (Oct 15, 2026 – Jan 14, 2027) |
|---|---|---|
| Standard-size | $0.78 / ft³ | $2.40 / ft³ |
| Large / oversize | $0.56 / ft³ | $1.40 / ft³ |
Storage charges volume, not weight. First convert your box to cubic feet:
Cubic feet = (L in × W in × H in) ÷ 1,728
Take a 6 × 4 × 2 in product: 48 in³ ÷ 1,728 = 0.028 ft³. Stored roughly 60 days off-peak: 0.028 × $0.78 × (60 ÷ 30) ≈ $0.04 per unit — the line item hiding in the worked $30 example. Same unit across Oct–December bills at $2.40 instead, about three times the bite.
The pricing implication is direct: slow stock is a fee problem before it is a cash problem. A unit that sells in 40 days costs a fraction of one sitting 120 — same product, same sale, different overhead. Faster turnover is the cheapest margin insurance you can buy.
The calculator applies $0.78/ft³ or $2.40/ft³ depending on the peak toggle and your average days in FBA:
Monthly storage = your unit's cubic footage times the monthly rate. Cubic feet = length × width × height in inches divided by 1,728. In 2026 standard-size storage is $0.78 per cubic foot off-peak and $2.40 during the Oct 15, 2026 – Jan 14, 2027 peak; a 6 × 4 × 2 in product stored 60 days costs roughly $0.04 per unit off-peak.