Profit Hawk
Free tool · For Amazon FBA sellers

Amazon Aged Inventory Risk Calculator
for FBA sellers.

Project which FBA units are heading for the aged-inventory surcharge — and how much cash is on track to sit in slow movers at 90, 180, 270, and 365 days from today.

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What question does this answer
“Which units are at risk of becoming aged inventory, and how much cash could be stuck in slow-moving FBA stock?”
1

Your FBA stock, today

We'll project how much of it survives 90, 180, 270, and 365 days at your current sales pace.

units
units
$ / unit
Add real aged-cohort numbers (optional)

If you've pulled your aged-inventory report from Seller Central, plug the cohort numbers in here. We'll use them instead of the projection.

units
units
units
units
Estimate aged surcharge exposure (optional)

The exact aged-inventory surcharge changes — verify the current rate in Seller Central. Enter your own assumption to see a rough monthly exposure on the 180+ day cohort.

ft³
$ / ft³
Recommended action
Discount or rebalance

Run a velocity push (promo, price, ads) or rebalance to AWD/3PL before the aged surcharge bites.

Current days of cover
300days
Cash in current FBA stock
$14,400
How your stock depletes365-day projection · 90 · 180 · 270 · 365
Stock depletion curve90d180d270d365d
2
Next ↓ keep going
See units & cash at each cohort + a monthly recheck so this never sneaks up
2

Projected aged cohorts & cash exposure

How much of today's stock is on track to still be there at each Amazon aged-inventory threshold.

90+ daysProjected
840units
≈ $10,080 cash
Projected
180+ daysAction line
480units
≈ $5,760 cash
Projected
270+ daysAction line
120units
≈ $1,440 cash
Projected
365+ daysSurcharge tier
0units
≈ $0 cash
Projected

Projections assume your current sales pace holds steady and no additional inbound. Amazon's aged inventory surcharge (sometimes still called the long-term storage fee) changes — always confirm the live schedule in Seller Central before budgeting.

Aged-risk plan + monthly recheck

Don't let $5,760 sit through the surcharge

One email. Today's risk + a monthly recheck so this doesn't slip past you.

At risk by day 180
$5,760
Action line
480units
  • This risk report as a PDF — cohorts, cash, recommended action
  • Monthly recheck email — same projection with fresh velocity
  • Multi-SKU template — run this for every SKU at once
One monthly recheck. Unsubscribe with one click.
How it works

The method, in plain English.

Two simple ideas: project how many units will still be sitting at each aged-inventory threshold, then convert those units into cash and (optionally) surcharge exposure.

Units remaining at day d =FBA units −avg daily sales × d
FBA
Today's stock. All units sitting in Amazon's fulfillment centers, regardless of age. If you have the cohort report, use the real aged numbers in the optional inputs.
d̄
Average daily sales. Last 30–60 days, excluding stockout days, with one-off promo spikes stripped out. This is your sell-through clock.
d
The cohort threshold. 90, 180, 270, and 365 days from today — the milestones at which Amazon's aged inventory surcharge progressively tightens.
$
Cash exposure. Units remaining × landed cost. Optional surcharge estimate = aged units × cubic-feet × your surcharge assumption.

Worked example

A long-tail FBA SKU that quietly slowed down after a strong launch.

Current FBA units1,200 units
Average daily sales4 units
Landed cost$12 / unit
Cubic feet per unit0.3 ft³
Days of cover1,200 ÷ 4 = 300 days
Units at 90 days1,200 − (4 × 90) = 840
Units at 180 days1,200 − (4 × 180) = 480
Cash at 180 days480 × $12 = $5,760
Action
Discount or rebalance
Watch out for

Common aged-inventory mistakes.

Aged inventory rarely surprises sellers because the math is hard — it surprises them because the assumptions are wrong. Here are the patterns we see most.

01

Treating today's sales pace as forever

Velocity slows in Q1, after seasonal peaks, and as listings drift. A 'fine' days-of-cover number in October can be a disaster in February if you don't re-run the projection.

Fix: Recompute monthly using a rolling 30–60 day sales window, not all-time averages.
02

Counting only today's stock, ignoring inbound

Aged inventory is about what's sitting in FBA. But if you have a big PO already on the water, your real exposure 90 days from now is much higher than today's projection suggests.

Fix: Subtract the inbound landing window from your projection horizon, or factor inbound into avg daily sales.
03

Confusing slow-moving with aged

A SKU that sells once a day is slow, but it isn't necessarily aged — it depends on how long each unit has physically been in FBA. Acting on velocity alone misses long-tail SKUs that quietly cross the surcharge threshold.

Fix: Always pair days-of-cover with the actual aged-cohort numbers from your FBA inventory aging report.
04

Waiting for the surcharge invoice to act

By the time the aged-inventory surcharge shows up in your statement, you've already paid two months of it and dragged your IPI down with it. Reactive removals at 365 days cost dramatically more than discounts at 180.

Fix: Treat the 180-day cohort as your action line, not the 365-day one.
05

Removing instead of discounting reflexively

Removal fees, return-to-supplier shipping, and disposal write-downs add up fast. For most categories, a 15–25% price cut moves the unit before the next surcharge tier and recovers more cost.

Fix: Model 'discount to clear' vs 'remove' for each SKU. Default to discount unless margin is already gone.
06

Using outdated Amazon fee language with finance

Calling it 'long-term storage fees' on a board deck makes the cost look like a known, capped problem. The modern aged-inventory surcharge is more aggressive and tiered, and finance partners need the current framing.

Fix: Speak in current Amazon language. Verify the live surcharge schedule in Seller Central before any budget exercise.
When this calculator isn't enough

Great for one SKU.
Painful for a whole catalog.

Modeling one SKU's aged-inventory exposure is straightforward. Doing it for every SKU, every week, with inbound and AWD and seasonality factored in — that's where a spreadsheet falls over.

  • Hundreds of SKUs, four cohorts eachManually tracking 90/180/270/365 buckets across a real catalog is a part-time job that nobody does consistently.
  • Inbound shipments in flightAged risk depends on what's landing next month, not just what's in FBA today — a number a spreadsheet can't keep up with.
  • AWD & 3PL units overlapReal cover depends on FBA + AWD + 3PL + inbound. A pure FBA aging report misses the bigger inventory picture.
  • Sell-through drifts every weekRun rate changes with seasonality, ads, and pricing — and so does your aged-inventory projection.
  • Surcharge tiers shiftAmazon's aged-inventory pricing has moved more than once. Your model has to follow it without you copying numbers from a memo.
  • Trade-off math: discount vs removePicking the cheaper action SKU-by-SKU at scale needs margin, surcharge, and removal costs lined up automatically.
▲ Profit Hawk

Track aged-inventory risk automatically.

Profit Hawk recomputes days of cover, aged cohorts, and projected surcharge exposure for every SKU using your real FBA, AWD, and 3PL data — and flags the ones that need a discount, rebalance, or removal before the surcharge hits.

  • 90 / 180 / 270 / 365 cohort tracking per SKU
  • Surcharge exposure auto-recomputed on rate changes
  • Discount vs remove vs rebalance recommendations
  • Replenishment alerts that respect aged risk
Start free trialSee Profit Hawk →
FAQ

Aged inventory, answered.

The questions Amazon sellers actually ask us about aged inventory, surcharge changes, and when to discount versus remove.

Is this the same as the old Amazon long-term storage fee (LTSF)?
It's the modern replacement. Amazon renamed and restructured what older sellers know as the long-term storage fee into the aged inventory surcharge, with thresholds that typically begin around 181 days and tighten further past 270 and 365 days. Rates change — always confirm the current schedule in Seller Central before you treat any surcharge number as final.
How is aged inventory different from slow-moving inventory?
Slow-moving means it's selling, just not fast enough — a velocity problem. Aged inventory is a clock: Amazon measures how long each unit has physically sat in an FBA warehouse since it was received. Slow movers turn into aged units if you don't intervene. This tool projects when that turnover is likely to happen so you can act early.
What's a reasonable days-of-cover threshold before I start worrying?
As a rule of thumb on Amazon: under 90 days of cover is healthy, 90–180 means you should slow your next PO, 180–270 calls for a velocity push or rebalance, and anything past 270 days needs a real plan — removal, discount, or AWD/3PL rebalance. The exact threshold depends on your category and margin, but FBA punishes sellers who sit on stock for almost any consumer category.
Should I always remove aged units?
No. Removal costs money and forfeits potential margin. Run the math: if a velocity push (price cut, ads, promo) can move the units before the next surcharge tier, that's often cheaper than removal. Only liquidate or remove when carrying cost + surcharge exposure clearly exceeds expected gross profit on the remaining sell-through.
Do I have to enter cubic feet and surcharge assumptions?
No — they're optional. The core projection (units remaining, cash tied up, days of cover) works without them. The surcharge exposure number is only useful if you want to translate aged units into a dollar-per-month estimate, and Amazon's rate schedule is exactly what you should plug in there. Leave it blank if you don't have a number handy.
What if I keep sending more inventory in?
The projection assumes no additional inbound. In reality, every new shipment refreshes the FIFO clock on incoming units but doesn't reset the clock on existing aged stock — those units keep aging. Until you sell or remove the older cohort, sending more in only deepens the problem.
Why does this matter for IPI and storage limits?
Aged inventory directly drags your Inventory Performance Index down, which can compress your storage capacity. So aged stock costs you twice: in surcharges on the slow units themselves, and in capacity you can't use for your fast movers. Clearing aged cohorts is one of the highest-leverage moves for opening up FBA headroom.
Can I use this for AWD or 3PL inventory?
AWD has its own aging logic and 3PLs typically charge by cubic foot regardless of age. Use this calculator specifically for FBA. For AWD and 3PL placement decisions, run the AWD vs FBA vs 3PL Storage Estimator instead.
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▲ Profit Hawk

Want this tracked automatically across all your Amazon SKUs?

Profit Hawk recalculates aged-inventory risk, days of cover, and surcharge exposure using your real Amazon FBA, AWD, and 3PL data — and recommends a specific action SKU by SKU.

Start free trialSee Profit Hawk