Free tool · For Amazon FBA sellers

Amazon Economic Order Quantity Calculator.

Find the order size that minimizes your total Amazon inventory cost — the sweet spot where fixed cost-per-PO stops shrinking and FBA holding cost starts hurting. Stop ordering six months at a time just because your freight quote looked good.

What question does this answer

“How many units should I order per PO so I'm not paying for the same supplier setup every month, and not paying FBA to babysit a year of stock either?”

Your economic order quantity

1,195

units

per purchase order

POs per year

10.0 / yr

At Q* cadence

Days between POs

36.4 days

Average cycle

Annual cost at Q* — ordering vs holding

Ordering$2,510

Holding$2,510

Total relevant cost$5,020

Next · keep going

Visualize where you sit on the cost curve

Visualize where you are on the curve

Drag your current order quantity. Watch the dot ride up the right side of the U as Q grows past the bottom.

Your current order quantity

What you're placing today, per PO

2,500u

Cost of being off the curve

Ordering 2,500 u/PO instead of 1,195 u costs you

+$1,430/ yr

That's 28.5% over the minimum cost.

Today's cost

$6,450

EOQ minimum

$5,020

Try a preset SKU profile

Your EOQ plan, in your inbox

Send the 1,195-unit plan + the multi-SKU toolkit

One email. Everything you need to turn this from a one-SKU sanity check into a system you can actually run against your whole catalog.

PDF of this calc — 1,195 units · 10.0 POs/yr · $5,020 annual costInstant
Multi-SKU template — Google Sheet, EOQ formulas baked in by A/B/C tierSheet
Extended calculator — quantity discounts · container / pallet rounding · safety stockTool
5-day FBA inventory playbook — one short email a day: EOQ, ROP, AWD, peak seasonCourse

How it works

One equation. Three honest inputs.

EOQ is older than e-commerce, but it still maps cleanly to an Amazon FBA seller's reality — IF you fill in the inputs without flinching.

Q* =√( 2 · D · S / H )

Annual demand. Forward-looking units sold per year — a weighted velocity that accounts for trend and seasonality, not last week's pace.

Ordering cost per PO. Fixed cost per order regardless of size: supplier setup, freight booking, customs broker, FBA inbound creation, your team's hours per PO at a real loaded cost.

Holding cost per unit per year. FBA storage + cost of capital + shrinkage / obsolescence, annualized per unit. For most FBA SKUs, 15–35% of landed unit cost.

The order size that minimizes total cost. At Q*, annual ordering cost equals annual holding cost. That's the bottom of the U-shaped total cost curve.

Worked example

A typical FBA hero SKU: 12,000 units / yr, $250 per PO, $4.20 per unit / yr to hold.

Annual demand (D)12,000 units / yr

Ordering cost (S)$250 per PO

Holding cost (H)$4.20 per unit / yr

2 · D · S6,000,000

2 · D · S / H1,428,571

√( 2 · D · S / H )≈ 1,195

Economic order quantity

≈ one PO every 36 days · 10.0 / yr

1,195 units

Watch out for

Common EOQ mistakes.

EOQ is one of the oldest equations in inventory management. It's also the one sellers most often apply lazily. These are the failure modes we see most.

Treating EOQ as a set-and-forget number

Demand, supplier cost, and FBA storage fees all move. Recompute when any input changes by more than ~15% — most sellers should re-tune at least quarterly, and again before Q4 peak.

Fix: Schedule a re-run when Q1, Q3, and pre-peak storage rate changes land.

Understating ordering cost (S)

“$50 to place a PO” is fantasy. Count freight booking, customs broker, supplier setup fees, FBA inbound creation, AND the hours your team spends per order at a real loaded cost.

Fix: A typical FBA seller's real S is $150–$400 per PO. Audit one real PO end-to-end before using a number.

Forgetting capital cost in H

Holding cost isn't just FBA storage. Capital cost (your hurdle rate, 12–25%) and shrinkage / obsolescence usually make up MORE of H than the storage line does — especially on $20+ landed SKUs.

Fix: Use H = (storage / unit / yr) + (capital cost % × landed unit cost) + (shrinkage % × landed unit cost).

Ignoring MOQs, case packs, and pallet quantities

EOQ tells you the textbook optimum. Supplier MOQ, case-pack size, and pallet rounding tell you the next legal Q above it. You always order the next valid step, not the raw EOQ.

Fix: Round UP to the next valid step. The cost curve near Q* is flat — small overshoots are nearly free.

Using EOQ on lumpy or new-launch SKUs

EOQ assumes steady, predictable demand. For SKUs with launch curves, single-buyer concentration, or violent seasonality, hold smaller and reorder more often than EOQ says.

Fix: Skip EOQ if your weekly demand CV (σ / μ) is above ~1.0 — switch to short-cycle replenishment.

Computing EOQ but still ordering by gut

The number does nothing in a Google Sheet. EOQ has to flow into your actual purchase orders — and the cadence has to lock into a reorder calendar that surfaces the trigger date.

Fix: Pair EOQ with the Reorder Point Calculator so Q sizes the buy and ROP triggers the PO date.

When this calculator isn't enough

Great for one SKU.
Brutal for a whole catalog.

The standard EOQ formula assumes one SKU, one supplier, steady demand, and known costs. Real Amazon catalogs break every one of those.

Quantity discountsTiered pricing from suppliers (e.g. 10% off at 5,000 units) bends the cost curve. The real optimum is often at the discount break, not the textbook Q*.
Stochastic demandEOQ assumes you know D. If demand has real variance, you also need a safety-stock buffer and a (Q, R) policy — EOQ for size, ROP for timing.
Joint replenishmentOrder multiple SKUs from one supplier on one container? Ordering cost is shared. Per-SKU EOQ overstates S and gives undersized POs.
FBA size-tier cliffsMonthly FBA storage isn't continuous — it jumps by size tier and date. H is a step function around Q4 inventory-placement deadlines.
Cash constraintsIf working capital is the binding constraint, the optimum is the largest Q you can fund — capped by EOQ — not EOQ itself.
Multi-node (FBA + AWD + 3PL)When inventory lives across multiple warehouses, holding cost varies by node and so does ordering cost. Per-node EOQ ≠ network EOQ.

▲ Profit Hawk

Compute EOQ automatically across every SKU.

Profit Hawk reads your real velocity, supplier prices, freight, and FBA storage fees and re-runs EOQ continuously — with quantity discounts, MOQ rounding, joint POs, and cash limits all baked in.

Per-SKU, per-supplier EOQ refreshed nightly
Container-fill and pallet-rounding aware
Cash-constrained reorder planning
Automated PO suggestions, not just numbers

Start free trial See Profit Hawk →

FAQ

EOQ, answered.

The questions sellers actually ask once they've punched the numbers in.

How is EOQ different from a reorder point?

EOQ answers HOW MUCH to order per PO. Reorder point answers WHEN to place the order. You need both — EOQ sizes the buy, ROP triggers the date. They work together as a complete (Q, R) inventory policy.

What if my supplier has a minimum order quantity (MOQ) above EOQ?

You order the MOQ. EOQ becomes a floor: don't go below the MOQ, but don't pad above it for round numbers either. If the MOQ is much larger than EOQ, that's a signal to renegotiate the MOQ or look for a more flexible supplier — you're paying real money for that gap in holding cost.

What if EOQ is below my MOQ or case pack?

Round up to the next valid step. The cost curve is shallow near Q* — being 10–20% above the textbook number costs you almost nothing. Most case packs and pallet quantities sit well inside that flat zone.

How often should I recompute EOQ?

When D, S, or H moves by more than ~15%. For most FBA sellers that means quarterly at minimum, plus before Q4 peak season when FBA storage fees roughly double and H jumps with them. Hero SKUs warrant monthly re-tunes if velocity is moving.

Should I include freight in S or in unit cost?

Variable freight (per unit) belongs in unit cost, which flows through holding cost (H). Fixed freight (per container, per booking, per LCL release) belongs in S. If you book a half-container, allocate proportionally based on the booking fee, not the cargo.

Does EOQ work with quantity discounts?

Not directly. Compute the textbook EOQ first, then check whether moving up to the next discount break beats it on TOTAL cost (discounted unit price × D + ordering cost at that Q + holding cost at that Q). It often does — the extra holding cost is usually smaller than the per-unit savings on a 5–10% break.

Why doesn't the total cost change much if I order a bit more or less than EOQ?

That's normal — and one of the most useful properties of the formula. EOQ is the minimum of a very forgiving U-shaped curve. Anywhere from roughly 0.7·Q* to 1.4·Q* is within a few percent of optimal. That's why rounding UP to MOQ, case pack, or pallet quantity rarely matters much.

How do I handle seasonality?

Use season-weighted demand for D, not a flat annual average. For pronounced peaks (Q4, Prime Day, Mother's Day), don't try to fit one EOQ across both modes — switch to a two-mode plan: pre-peak build, then EOQ-paced reorders through the off-peak months.

What goes into the holding cost (H)?

FBA base storage, the cost of capital (your hurdle rate, usually 12–25%), aged inventory surcharge exposure, and shrinkage / obsolescence — all annualized, per unit. For a typical FBA SKU at $15 landed, H is rarely below $3/yr; for oversize or slow-movers it can be $10–20+. Most sellers undercount H by 2–3× because they only count FBA storage.

Is EOQ still relevant for Amazon sellers in 2026?

Yes — arguably more than ever. FBA storage fees climbed again in 2026, and the 2026 aged inventory surcharge schedule punishes oversized POs harder than ever past day 270. EOQ is the cleanest answer to the question 'how much PO is too much before storage starts eating my margin?'

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