01
Find your metrics in Seller Central
Go to Seller Central → Inventory Performance Dashboard. Your in-stock rate, sell-through rate, excess inventory %, and stranded inventory % are all shown on this page.
Amazon IPI Score Calculator
Estimate your IPI score and find which factor is pulling it below 400.
Updated Reviewed by Sajid Hussain· Editor
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June 7, 2026
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Amazon FBA inventory health
Amazon IPI score: what the four factors tell you and how to fix them
The Amazon Inventory Performance Index (IPI) is a 0–1,000 score that measures how efficiently FBA sellers manage their warehouse inventory — based on four factors Amazon discloses: in-stock rate, sell-through rate, excess inventory percentage, and stranded inventory percentage. Sellers below 400 at the quarterly assessment face storage limits and may be blocked from creating new inbound shipments. This tool estimates your IPI from those four metrics and identifies which factor is creating the most drag.
Important disclaimer: Amazon does not publish its exact IPI formula. This calculator is an estimator based on the four publicly disclosed factors and community reverse-engineering. Use it for directional guidance — not as a precise predictor of your actual Seller Central IPI score.
The Inventory Performance Index (IPI) measures how well you manage FBA inventory across four dimensions. In-stock rate is the most heavily weighted — it measures what percentage of time your products are available for sale. Sell-through rate measures how quickly inventory moves relative to what you hold. Excess inventory penalises overstocking (more than 90 days of supply). Stranded inventory penalises units sitting in Amazon warehouses without an active listing.
Amazon requires a minimum IPI of 400. Sellers below this threshold face storage limits per storage type and restrictions on new inbound shipments. IPI is evaluated quarterly — a drop below 400 at the assessment date triggers limits that take effect six weeks later.
The most common IPI problems are: out-of-stocks (low in-stock rate) caused by underordering, excess inventory from over-ordering or slow-moving SKUs, and stranded inventory from suppressed listings that have not been fixed. Each has a clear remedy — and this calculator shows which of the four factors to address first.
Quick facts
- Factors modeled
- 4 disclosed IPI factors
- Score range
- 0–1000 estimated IPI
- Risk detection
- Below-400 warning + storage limit flag
- Issue diagnosis
- Identifies primary factor dragging score
- Disclaimer shown
- Estimator — not Amazon's proprietary formula
- Time to result
- < 5 seconds
How it works
From 4 Seller Central metrics to an estimated IPI score
Pull four numbers from your Seller Central Inventory Performance Dashboard, enter them here, and see your estimated IPI score and the factor creating the most drag.
02
Enter the four values
In-stock rate and sell-through rate contribute to your score. Excess and stranded inventory rates are penalised. Enter each from your Seller Central dashboard.
03
See your estimated IPI and component breakdown
The estimated IPI shows your approximate score and whether you are above the 400 minimum. The component scores show exactly how much each factor contributes or deducts.
04
Identify the primary issue and act
The primary issue output identifies which of the four factors is creating the most drag on your score. Fix that one factor first for the fastest IPI improvement.
Steps to use the Amazon IPI Score Calculator: Find your metrics in Seller Central, Enter the four values, See your estimated IPI and component breakdown, Identify the primary issue and act.
Estimation model
How this IPI estimator works
This tool uses an approximation model based on Amazon's four disclosed factors and publicly available community analysis. Amazon's actual formula is proprietary — treat all outputs as directional estimates.
01
In-Stock Score (0–400)
In-Stock Score = In-Stock Rate % ÷ 100 × 400
In-stock rate is the most heavily weighted IPI factor according to Amazon. A 100% in-stock rate earns the full 400 points; 90% earns 360 points.
Example: 90% in-stock rate → 90 ÷ 100 × 400 = 360 points
02
Sell-Through Score (0–300)
Sell-Through Score = min(Sell-Through Rate ÷ 4.0, 1) × 300
Amazon targets a sell-through rate of 4.0+ (90-day units sold ÷ average units on hand). At 4.0 or above, you earn the full 300 points. Below 4.0, the score scales proportionally.
Example: Sell-through 3.0 → min(3.0 ÷ 4.0, 1) × 300 = 0.75 × 300 = 225 points
03
Excess Inventory Penalty (0–200)
Excess Penalty = Excess Inventory % ÷ 100 × 200
Inventory with more than 90 days of supply coverage is flagged as excess. Higher excess rates reduce your IPI score.
Example: 20% excess → 20 ÷ 100 × 200 = 40 points deducted
04
Stranded Inventory Penalty (0–100)
Stranded Penalty = Stranded Inventory % ÷ 100 × 100
Units stored at Amazon with no active listing are stranded. Amazon penalises sellers for holding unsellable inventory.
Example: 5% stranded → 5 ÷ 100 × 100 = 5 points deducted
05
Estimated IPI
IPI = round(clamp(In-Stock Score + Sell-Through Score − Excess Penalty − Stranded Penalty, 0, 1000))
The combined score, clamped to the 0–1000 range. Amazon's exact formula differs — use this as a directional estimate.
Example: 360 + 225 − 40 − 5 = 540 estimated IPI
Worked example
Healthy baseline: 90% in-stock, 20% excess — what the score looks like
A typical mid-tier FBA seller scenario with realistic metrics from the Inventory Performance Dashboard.
Scenario
Your Inventory Performance Dashboard shows 90% in-stock rate, 20% excess inventory, 5% stranded inventory, and a 3.0 sell-through rate. Here is how the estimated IPI score is computed.
1
Step 1 · In-stock score
90% ÷ 100 × 400 = $360.00 points. This is the biggest contributor — a 100% in-stock rate would add another 40 points.
$360.00 points (of 400)
2
Step 2 · Sell-through score
3.0 ÷ 4.0 benchmark × 300 = $225.00 points. A sell-through rate of 4.0 or above earns the full 300.
$225.00 points (of 300)
3
Step 3 · Excess inventory penalty
20% excess inventory → 20% ÷ 100 × 200 = $40.00 points deducted. Reducing excess to under 10% would save 20 of these points.
−$40.00 points
4
Step 4 · Stranded inventory penalty
5% stranded → 5% ÷ 100 × 100 = $5.00 points deducted. Fixing stranded listings to 0% would recover all $5.00 points.
−$5.00 points
The takeaway
Estimated IPI: $360.00 + $225.00 − $40.00 − $5.00 = 540. Above the 400 minimum, but with clear room to improve by reducing excess and fixing stranded inventory.
IPI score benchmarks
What different IPI ranges mean for your Amazon FBA account
Amazon evaluates IPI quarterly. Sellers below 400 at the assessment date face storage limits and shipment restrictions. Higher scores may unlock storage benefits.
| Metric | Poor | Average | Good | Excellent |
|---|---|---|---|---|
IPI below 400 — storage limits + shipment restrictions Amazon Seller Central — Inventory Performance Index | Yes | Risk zone | No | No |
IPI 400–550 — above minimum, at risk if score falls Amazon Seller Central — Inventory Performance Index | Below this | 400–550 | Above this | Above this |
IPI 550–700 — healthy range, unrestricted storage Amazon Seller Central — Inventory Performance Index | Below 550 | 550–700 | 550–700 | Above 700 |
IPI 700+ — excellent, top-tier inventory health Amazon Seller Central — Inventory Performance Index | Below 400 | 550–700 | 700+ | 750+ |
Target in-stock rate (most important factor) Amazon Inventory Performance Dashboard guidance | < 75% | 75–85% | 85–95% | > 95% |
Tool comparison
Calcrux vs. other IPI tools
| Feature | Feature | Calcrux (free) | SellerApp IPI Dashboard | Seller Central (native) |
|---|---|---|---|---|
| IPI estimation from 4 factors | ||||
| Component score breakdown | ||||
| Primary issue diagnosis | ||||
| Below-400 warning with storage limit flag | ||||
| Works without Amazon account connection | ||||
| Shows actual IPI (not estimate) | ||||
| Historical IPI trend | ||||
| No subscription required |
Common mistakes
IPI mistakes that push sellers below 400 unnecessarily
Ignoring stranded inventory
Why it matters
Stranded inventory — units stored at Amazon without an active listing — accrues storage fees and deducts from IPI. Many sellers let stranded inventory build up for weeks without checking the report.
Fix
Check the "Fix Stranded Inventory" report in Seller Central weekly. Relist or remove all stranded units. Even 5% stranded inventory deducts meaningful IPI points.
Over-ordering to avoid stockouts without tracking the excess flag
Why it matters
Sending more inventory than 90 days of demand reduces the risk of stockouts but increases excess inventory percentage — which penalises IPI. The balance between stockout risk and excess inventory is the core IPI management challenge.
Fix
Use the FBA Restock Calculator to send 60–90 days of inventory rather than 120–180. Match replenishment frequency to supply chain lead time, not worst-case demand.
Low sell-through rate on new or seasonal products
Why it matters
A new product with slow initial velocity and high inventory levels will have a low sell-through rate — reducing IPI before the product has had time to establish demand.
Fix
For new launches, send smaller initial quantities (30–45 days of projected demand), use coupons and promotions to build velocity, and restock as sell-through improves.
Treating IPI as a one-time fix rather than an ongoing metric
Why it matters
IPI is assessed quarterly. Sellers who fix it right before the assessment date and then let it slip again face recurring storage limit cycles.
Fix
Check IPI monthly. Set up automated alerts for stranded inventory and excess flags. Make IPI management part of your weekly inventory review.
Using this estimator as a precise predictor
Why it matters
Amazon's IPI formula is proprietary. This calculator models the four disclosed factors but cannot replicate Amazon's exact weighting and interactions. Your actual IPI in Seller Central may differ.
Fix
Use this tool to identify which factor to fix and approximate the direction of change — not to predict the exact IPI number. Always check your actual score in Seller Central after making changes.
Pro tips
How to raise your Amazon IPI score systematically
Fix stranded inventory first
Stranded inventory can often be fixed in minutes (relisting a suppressed listing, correcting a price error, updating a compliance document). It penalises IPI immediately and fixing it gives you a measurable score improvement within 1–2 weeks.
Remove excess before assessment date
If excess inventory is above 30%, create removal orders for the slowest-moving SKUs. Amazon charges a removal fee (0.97–3.12 per unit in USD), but this is almost always cheaper than the combined storage fees and IPI penalty from holding excess stock.
Prioritise in-stock on top ASINs
In-stock rate is weighted most heavily in the IPI score. If you have to choose which ASINs to restock when budget is tight, prioritise the ones with highest sales velocity — they have the most impact on in-stock rate.
Clear near-excess with promotions
Units with 75–90 days of supply can cross into excess territory quickly if sales slow. A targeted coupon or lightning deal can clear the oldest inventory, reduce storage fees, and improve both sell-through rate and excess inventory rate simultaneously.
Check Seller Central IPI weekly
Amazon updates IPI weekly. After making inventory changes (fixing stranded, removing excess, sending a restock), check your actual IPI score the following week to validate the improvement. This feedback loop lets you course-correct quickly before the quarterly assessment date.
Who uses this
When sellers reach for the IPI Score Calculator
The Amazon IPI Score Calculator works across every stage of the workflow.
Seller approaching the quarterly IPI assessment date
Checks estimated IPI six weeks before the assessment, identifies which factor is dragging the score below 400, and has enough time to remove excess inventory and fix stranded listings before the assessment.
New FBA seller understanding IPI for the first time
Uses the estimator to understand how each of the four factors affects the score and which actions move the needle most before sending their first large shipment.
Seller who received a storage limit notification
Enters current metrics to see which factor caused the drop below 400, then creates an action plan focused on the primary issue (most commonly excess inventory or stranded listings).
Amazon PPC or inventory manager explaining IPI to a client
Uses the calculator to show clients the component breakdown — making it concrete that stranded listings and excess stock are costing them IPI points, not just abstract "inventory health" issues.
Multi-account seller managing IPI across several brands
Runs each account's metrics through the estimator during weekly review to identify which accounts are approaching the 400 threshold and need immediate action.
Glossary
Amazon IPI and inventory terms explained
Every important term you'll encounter in this calculator and the broader topic.
- IPI (Inventory Performance Index)
- A score (0–1000) Amazon assigns to FBA sellers measuring inventory management health across four factors: in-stock rate, sell-through rate, excess inventory, and stranded inventory. Sellers below 400 at the quarterly assessment face storage limits. Amazon does not publish the exact formula.
- In-Stock Rate
- The percentage of time your FBA listings were buyable over the trailing 30 days. The most heavily weighted IPI factor. Stockouts — when inventory runs out and the listing becomes unavailable — directly reduce in-stock rate and IPI.
- Sell-Through Rate
- Units sold in the trailing 90 days divided by average units on hand over the same period. Amazon targets 4.0+. A sell-through rate below 2.0 indicates slow-moving inventory and reduces IPI.
- Excess Inventory
- FBA units with more than 90 days of supply coverage (current units ÷ daily sell rate). Amazon flags these as excess because they occupy warehouse space beyond what near-term demand requires. High excess inventory penalises IPI.
- Stranded Inventory
- FBA units stored at Amazon warehouses that have no active listing — they cannot be purchased by customers. Common causes: suppressed listings (policy violations, price errors, compliance issues), or deleted ASINs. Stranded inventory is penalised in IPI because it generates storage costs without generating sales.
Help & answers
Frequently asked questions
Everything you need to know about how the Amazon IPI Score Calculator works.
01What is the Amazon IPI score?
The Inventory Performance Index (IPI) is a score Amazon assigns to FBA sellers, ranging from 0 to 1000. It reflects how well you manage your FBA inventory across four factors: in-stock rate, sell-through rate, excess inventory, and stranded inventory. Amazon requires a minimum IPI of 400 — sellers below this threshold face storage limits and restrictions on creating inbound shipments.
02What IPI score do I need to avoid Amazon storage limits?
Amazon requires an IPI score of at least 400 to maintain unrestricted FBA storage. Sellers who fall below 400 face storage limits per storage type (standard-size, oversize, etc.) and may be restricted from sending new inbound shipments until the score improves. Some sellers report informal thresholds for additional benefits above 600 and 750.
03What factors make up the Amazon IPI score?
Amazon discloses four factors that influence IPI: (1) In-stock rate — the percentage of time your products are buyable; (2) Sell-through rate — units sold per unit on hand over 90 days; (3) Excess inventory — the percentage of inventory with more than 90 days of supply; (4) Stranded inventory — inventory stored at Amazon without an active listing. Amazon weights in-stock rate most heavily.
04Is there a public Amazon IPI formula?
No — Amazon does not publish the exact mathematical formula for IPI. The four contributing factors are publicly disclosed, but the precise weights and interactions are proprietary. This calculator uses an estimation model based on the four disclosed factors and community reverse-engineering. It is designed for directional guidance — your actual IPI in Seller Central may differ.
05How is the Amazon IPI score calculated in this tool?
This estimator uses an approximation model: IPI ≈ (In-Stock Rate × 4) + (min(Sell-Through ÷ 4.0, 1) × 300) − (Excess % × 2) − (Stranded % × 1). In-stock rate contributes up to 400 points, sell-through up to 300 points, and excess and stranded inventory each deduct up to 200 and 100 points respectively. This is an estimate — the actual Amazon formula is proprietary.
06Where do I find my IPI inputs in Seller Central?
In-stock rate and sell-through rate: Seller Central → Inventory Performance Dashboard. Excess inventory rate: Seller Central → Manage Excess Inventory report. Stranded inventory rate: Seller Central → Fix Stranded Inventory. All four metrics appear on the Inventory Performance Dashboard page.
07How can I improve my Amazon IPI score?
The highest-impact improvements by factor: (1) In-stock rate — use a restock calculator to prevent stockouts; (2) Sell-through rate — use promotions, coupons, or price reductions to accelerate sales velocity; (3) Excess inventory — create removal orders for slow-moving stock over 90 days of supply; (4) Stranded inventory — use "Fix Stranded Inventory" in Seller Central to relist or remove all stranded units.
08How often does Amazon update the IPI score?
Amazon updates the IPI score weekly. Changes you make to your inventory this week — fixing stranded listings, removing excess inventory, improving in-stock rate — will be reflected in your IPI score within 1–2 weeks. Amazon evaluates IPI quarterly to determine whether storage limits apply.
09What happens if my IPI drops below 400?
If your IPI falls below 400 at the quarterly assessment date, Amazon will set storage limits on your account. These limits cap the maximum cubic feet you can store in each storage type (standard, oversize, etc.). Creating new inbound shipments may be restricted until your IPI improves. Storage limits typically take effect about six weeks after the assessment date.
10What is a good IPI score on Amazon?
Score ranges as a general guide: below 400 = at risk of storage limits and restrictions; 400–550 = above minimum but at risk if score falls; 550–700 = healthy range with unrestricted storage; 700+ = excellent, associated with the highest-performing FBA sellers. Amazon periodically awards storage rewards for high-IPI sellers.
11Does IPI affect my FBA fees?
IPI does not directly affect individual FBA fees. However, a low IPI that results in storage limits can indirectly increase costs by forcing you to store excess inventory outside of FBA (adding third-party storage and shipping costs) or by restricting your ability to replenish inventory efficiently.
12Can I use this IPI calculator for non-US Amazon marketplaces?
Amazon has introduced IPI-equivalent inventory performance metrics in most major marketplaces (UK, DE, JP, etc.), but the specific thresholds and scoring may vary. This calculator models the US Amazon IPI system. Use it as a directional tool for any marketplace — the four factors are consistent across markets even if the exact formula differs.
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Topics
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