Free Tool No Signup Required Instant Results Built for Businesses
Inventory Stock Calculator
Calculate optimal stock levels, reorder points, safety stock, EOQ, carrying costs, and turnover ratio — in seconds. Built for inventory managers, warehouse teams, and small business owners.
6
Calculators
Free
Always
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Results
0
Signup Needed
6 Built-in Calculators
Reorder Point
When to reorder stock
Safety Stock
Buffer inventory level
EOQ
Optimal order quantity
Carrying Cost
Annual holding expenses
Stock Turnover
Inventory efficiency ratio
Days on Hand
Stock runway estimate
Instant Calculations
Free, No Signup
Smart Insights on Every Result
Built for Businesses of All Sizes
How It Works
Get your inventory numbers in 3 simple steps
Step 1
Select Your Calculator
Choose from 6 inventory calculators using the tabs below. Each one solves a specific inventory challenge.
Step 2
Enter Your Numbers
Fill in your daily sales, lead times, or cost figures. Every field has a tooltip explaining what it means.
Step 3
Get Instant Results
See your results instantly with a plain-English explanation of what the numbers mean and what action to take.
Reorder Point Calculator
Find the exact stock level at which you should place a new order — so you never run out.
Currency:
Enter Your Values
units
days
units
Your Results
Reorder Point
—
units
Demand During Lead Time
—
units needed
Maximum Stock Needed
—
units peak
Formula Used
Reorder Point = (Average Daily Sales × Lead Time) + Safety Stock
Safety Stock Calculator
Calculate the buffer inventory needed to protect against unexpected demand spikes or supply delays.
Enter Your Values
units
units
days
days
Your Results
Safety Stock
—
units buffer
Demand Variability
—
units/day swing
Lead Time Variability
—
days swing
Formula Used
Safety Stock = (Max Daily Sales − Avg Daily Sales) × Max Lead Time + Avg Daily Sales × (Max Lead Time − Avg Lead Time)
Economic Order Quantity (EOQ) Calculator
Find the optimal order quantity that minimises total ordering and holding costs.
Enter Your Values
units
$
$
Your Results
Optimal Order Qty
—
units per order
Orders Per Year
—
times/year
Total Annual Cost
—
ordering + holding
Order Cycle
—
days between orders
Formula Used
EOQ = √ ( 2 × Annual Demand × Ordering Cost ÷ Holding Cost Per Unit )
Inventory Carrying Cost Calculator
Understand the true annual cost of holding your inventory, including storage, insurance, and depreciation.
Enter Your Values
$
$
$
%
%
$
Your Results
Total Annual Carrying Cost
—
per year
Carrying Cost Rate
—
of inventory value
Monthly Cost
—
per month
Daily Cost
—
per day
Inventory Turnover Ratio Calculator
Measure how many times your inventory is sold and replaced in a year — a key indicator of business efficiency.
Enter Your Values
$
$
$
Your Results
Turnover Ratio
—
times per year
Average Inventory
—
average value
Days to Sell Stock
—
days average
Formula Used
Turnover Ratio = COGS ÷ Average Inventory | Average Inventory = (Opening + Closing) ÷ 2
Days Inventory On Hand (DOH) Calculator
Find out how many days your current stock will last at your current sales rate.
Enter Your Values
units
units
$
Your Results
Days on Hand
—
days of stock
Weeks on Hand
—
weeks of stock
Stock Value
—
total at cost
Stockout Date
—
if no restock
Formula Used
Days on Hand = Current Stock ÷ Average Daily Sales
Inventory Planning Flow
How inventory decisions connect
Every number you calculate feeds into the next decision. This is how professional inventory management works.
Demand
Forecast
Average daily sales rate
Buffer
Safety Stock
Protect against demand spikes
Trigger
Reorder Point
Level that triggers ordering
Quantity
EOQ
Optimal units per order
Replenish
Purchase Order
Order placed & delivered
Learn the Formulas
Why Inventory Calculations Matter
Poor inventory management costs businesses an estimated $1.1 trillion globally in overstocking and stockouts every year. Understanding these formulas prevents that.
What is a Reorder Point?
A reorder point (ROP) is the inventory level at which you should place a new purchase order. It accounts for average daily demand multiplied by lead time, plus a safety buffer — ensuring you never run out of stock while waiting for a delivery.
What is Safety Stock?
Safety stock is extra inventory kept as a buffer against unexpected spikes in demand or supplier delays. It's calculated using the difference between maximum and average demand, multiplied by maximum lead time. Too little causes stockouts; too much wastes capital.
What is EOQ?
Economic Order Quantity (EOQ) is the ideal number of units to order each time you replenish stock. It balances two competing costs: the cost of ordering too frequently vs. the cost of holding too much inventory. The formula minimises the total of both.
What is Inventory Turnover?
Inventory turnover ratio measures how many times your stock is sold and replaced in a year. A high ratio (e.g. 8–12×) indicates efficient operations. A low ratio means capital is tied up in slow-moving stock. Most healthy retail businesses target 6–10×.
What are Carrying Costs?
Inventory carrying costs are the total expenses of holding stock — including warehousing, insurance, depreciation, and opportunity cost. Industry average is 20–30% of inventory value per year. Knowing this helps justify investments in faster-moving stock.
What is Days on Hand (DOH)?
Days Inventory on Hand (DOH) tells you how many days your current stock will last before running out. It's calculated by dividing current units by average daily sales. This helps plan reorder timing and spot slow-moving inventory before it becomes a problem.
Related Tools & Software
Ready to automate these calculations?
These calculators give you the numbers. InventorysHub tracks them automatically — in real time, for your entire business.
How do I calculate the reorder point for my business?
Multiply your average daily sales by your supplier's lead time in days, then add your safety stock. For example: if you sell 50 units/day, lead time is 7 days, and safety stock is 100 units — your reorder point is (50 × 7) + 100 = 450 units. Use the Reorder Point calculator above to get your result instantly.
What is a good inventory turnover ratio?
It varies by industry. Grocery and FMCG businesses typically see 12–30×, while electronics or furniture might be 4–8×. Generally, a ratio above 6× indicates healthy stock movement. Below 3× often signals overstocking or slow-moving products that may need discounting or discontinuation.
How much safety stock should I keep?
Safety stock depends on demand variability and supplier reliability. The standard formula is: (Maximum Daily Sales − Average Daily Sales) × Maximum Lead Time. If your sales and supplier are very consistent, you need less safety stock. If demand is unpredictable or your supplier often delays, keep more. Use the Safety Stock calculator above for your specific numbers.
Is this inventory calculator free to use?
Yes. All six calculators on this page — Reorder Point, Safety Stock, EOQ, Carrying Cost, Stock Turnover, and Days on Hand — are completely free with no signup, no registration, and no limits. This tool is provided by InventorysHub as a free resource for inventory managers and small business owners.
What is EOQ and when should I use it?
EOQ (Economic Order Quantity) is most useful when your demand is relatively stable and you have measurable ordering and holding costs. It helps you avoid both over-ordering (which increases storage costs) and under-ordering (which increases ordering frequency and shipping costs). It's ideal for businesses ordering the same products repeatedly from the same suppliers.
What is the average inventory carrying cost rate?
The industry average inventory carrying cost is typically 20–30% of the total inventory value per year. This includes warehousing (3–5%), insurance (1–2%), depreciation/obsolescence (5–15%), and capital/opportunity cost (8–12%). If your carrying cost rate is above 35%, it's a signal to reduce stock levels or improve turnover.