Ochrequiet invoicing

Free tool

Find the order size that costs you the least.

Enter your annual demand, the cost of placing one order, and what it costs to hold one unit for a year, and this finds the order quantity where ordering and holding costs balance out at their lowest combined total.

Nothing you type here ever leaves your browser. There's no server behind this page — every figure is calculated locally, on your device, the same local-first idea behind the Ochre app.

Reviewed 2026-08-11

What it costs you to place and receive one order — admin time, shipping, receiving.

Storage, insurance and the cost of the cash tied up in one unit for a year.

Results

Assumptions this model makes

EOQ's honesty is in what it doesn't pretend to know.

  • Constant, known demand — real demand fluctuates with seasons and promotions; EOQ assumes a steady annual rate.
  • Fixed order and holding costs — a supplier's rush fee or a warehouse's seasonal storage surcharge isn't modeled.
  • No quantity discounts — a supplier's price break at 500 units can make ordering above the "optimal" EOQ genuinely cheaper overall.
  • No stockouts — the model has no cost for running out; pair EOQ with a reorder point that includes a real safety buffer.

More inventory tools

EOQ answers how much to order. These answer when, and what to call it.

Reorder point calculator

Work out exactly when to reorder, from your usage rate, lead time and safety stock.

Inventory turnover calculator

Check how many times a year your stock turns over, and how long it sits.

SKU generator

Build clean, unambiguous SKU codes from category, size and color segments.

Questions

What is Economic Order Quantity (EOQ)?
The order size that minimizes your total inventory cost — ordering cost (placing and receiving an order) plus holding cost (storing, insuring and tying up cash in stock). Order too little and you pay ordering costs too often; order too much and holding costs pile up. EOQ is the balance point.
Why does EOQ need a square root?
The formula is EOQ = √(2 × Annual demand × Order cost ÷ Holding cost per unit) — it comes from finding where total ordering cost and total holding cost, plotted against order size, cross over. That crossing point is a genuine square root, almost always an irrational number, which is why the answer is rounded to a whole unit before you can actually place an order.
What does EOQ assume that might not be true for my business?
It assumes constant, known demand, fixed order and holding costs, and no quantity discounts or stockouts. Real suppliers often give a price break at higher quantities, and real demand fluctuates seasonally — either of those moves the true optimum away from this number, so treat EOQ as a starting point, not a rule.
How is holding cost as a percentage different from a fixed amount?
Many businesses think of holding cost as a percentage of what the unit is worth (storage, insurance, and the opportunity cost of the cash tied up) rather than a flat figure — this calculator lets you enter either, and converts the percentage to a per-unit amount for you.
More free inventory tools SKU generator, reorder point and turnover calculators, all free and private.
Browse inventory tools

What this page cannot do

The number is not the order.

This page works out an ideal batch size from demand, ordering cost and holding cost you type in — useful, and disconnected from what you actually hold or have already ordered. Ochre stores a stock quantity and a purchase price on every product, and a purchase order you send to a vendor is a real, dated document — so when you act on a number like this one, it leaves a record instead of a browser tab you are about to close.