Free Amazon FBA
calculators & tools.
Practical calculators built for Amazon sellers, covering inventory planning, cash flow, and FBA fees. Each one answers a real question with a real number, in plain English.
Decide what to reorder, and when.
Safety Stock Calculator
Calculate the buffer inventory you need to avoid Amazon FBA stockouts during lead time variability. Free, no signup.
Reorder Point Calculator
Find the on-hand level that should trigger your next PO so Amazon FBA stock arrives before you run out. Free, no signup.
Amazon Reorder Lead Time Calculator
Add up every step from PO to FBA shelf — production, freight, customs, prep, ground, and Amazon receiving — to find your true reorder lead time. Free, no signup.
Amazon EOQ Calculator
Find the order size that minimizes your total Amazon inventory cost — the sweet spot where fixed per-PO cost stops shrinking and FBA holding cost starts hurting. Free, no signup.
Promotion Inventory Planner
Plan how much inventory you need before Prime Day, a coupon, a deal, or a seasonal promo — without running out mid-event. Free, no signup.
Inventory Days of Supply Calculator
See how many days of cover your Amazon FBA inventory provides — across on-hand, inbound, and AWD/3PL — at your real sales velocity. Free, no signup.
Spot slow movers and storage risk early.
Inventory Turnover & GMROI Calculator
Measure how fast your inventory turns and how much gross margin it generates per cash dollar tied up. Free, no signup.
Sell-Through Rate Calculator
Measure how quickly inventory turns over to spot slow movers before they tie up cash.
IPI Score Calculator
Estimate your Inventory Performance Index drivers and the storage limits Amazon may impose.
Amazon Aged Inventory Risk Calculator
Project how much of your FBA stock is at risk of becoming aged inventory — and how much cash could be stuck in slow movers before Amazon's aged inventory surcharge bites.
FBA Capacity Usage Calculator
See how much of your Amazon FBA storage capacity is in use, how much is left, and whether your next shipment will actually fit. Free, no signup.
AWD vs FBA vs 3PL Storage Estimator
Estimate where extra Amazon inventory should sit — FBA, AWD, or a 3PL — based on storage cost, sell-through speed, and transfer fees. Free, no signup.
Know your true margin and your true cash position.
Amazon Stockout Cost Calculator
Estimate the lost revenue and gross profit when an Amazon FBA SKU goes out of stock — direct impact plus optional post-stockout recovery drag. Free, no signup.
Cash Tied Up in Inventory Calculator
See how much cash is locked in this Amazon FBA SKU and how much of it is excess above your target days of cover. Free, no signup.
Amazon FBA Storage Fee Calculator
Estimate Amazon FBA base monthly storage fees and aged inventory surcharges for a single PO from arrival to sell-through — with Q4 peak rates and the 2026 aged surcharge schedule. Free, no signup.
FBA Fee Estimator
Estimate referral, fulfillment, and storage fees before you launch a new product.
How to use these calculators together.
Each tool answers one question. Run them in order and you'll have a defensible PO size, a clear reorder trigger, and a real read on what each SKU is costing you to hold.
- 01
Start with demand
Use the Days of Supply and Safety Stock calculators to translate raw sales velocity into a buffer that protects against lead-time variability.
- 02
Set the trigger
Drop your safety stock into the Reorder Point Calculator to find the on-hand level that should kick off your next PO, before stockouts rather than after.
- 03
Audit inventory health
Run Sell-Through Rate, IPI Score, and Aged Inventory Risk to find the SKUs hurting your storage limits and your warehouse efficiency.
- 04
Price the consequences
Use Stockout Cost, Cash Tied Up in Inventory, and the FBA Fee Estimator to translate inventory decisions into dollars so you can make the right trade-off, not just the safe one.
About these free FBA tools.
Common questions sellers ask before using the calculators. If you need something the tools don't cover, the longer guides on each page go deeper.
Are these calculators really free?
Which calculator should I start with?
Do these work for AWD and 3PL inventory too?
How accurate are the FBA fee estimates?
Can I use these for multiple marketplaces?
Do I need a math or stats background?
Like the calculators? Profit Hawk runs them across your whole Amazon catalog.
Built for sellers who've outgrown spreadsheets. Connect Seller Central and Profit Hawk recalculates inventory, cash, and fee math continuously, with no copying numbers between tabs.