12 free calculators
Free supply chain tools and calculators
Work out safety stock, reorder points, landed cost, tariff impact, GMROI, open-to-buy and forecast accuracy from your own numbers, in seconds. Built for manufacturers, distributors and retailers.
- No sign-up
- Runs in your browser
- Nothing you enter is stored or sent
Pick a calculator
Each calculator answers a different question. Find yours, then read the matching guide for the method and its limits.
Inventory and demand
Set stock levels, time your orders and check your forecast.
How much buffer do we need?
Safety stock calculator
Set buffer stock and a reorder point from demand and lead-time variability.
Open calculatorSafety stock formula
When should we reorder?
Reorder point calculator
Find when to reorder from daily demand, lead time and safety stock.
Open calculatorReorder point formula
How much should we order at once?
Economic order quantity calculator
Find the order quantity that balances ordering and holding costs.
Open calculatorEOQ vs MOQ
Is our inventory moving fast enough?
Inventory turnover calculator
Work out turns, days of inventory and annual carrying cost.
Open calculatorGood turnover ratio
How good is our forecast?
Forecast accuracy calculator
Paste forecast and actual columns to get WAPE, MAPE and bias.
Open calculatorForecast accuracy formula
Retail
See what earns its shelf space and how much you can still buy.
Which stock earns the most?
GMROI calculator
See the gross margin earned for every dollar held in stock.
Open calculatorGMROI formula
How much can we still buy?
Open-to-buy calculator
Work out how much new stock a retailer can still buy this month.
Open calculatorOpen-to-buy formula
Is this product selling on pace?
Sell-through rate calculator
See the share of stock sold and whether you are on pace.
Open calculatorSell-through formula
Cost and trade
Know what a part really costs once freight and duty are in.
What does this part really cost us?
Landed cost calculator
Add freight, duty and fees to the ex-works price to see your true cost per unit.
Open calculatorLanded cost guide
What will a tariff change cost?
Tariff cost calculator
See how a duty change affects your landed unit cost and margin.
Open calculatorCut tariff costs
How much fits in a container?
Container load calculator
Estimate cartons per 20ft, 40ft and 40ft HC container from carton size and weight.
Open calculator
About these tools
- Standard formulas. Each calculator uses a standard, simple formula and the numbers you type in.
- Private. Nothing you enter is sent anywhere or stored.
- For planning only. These tools give estimates for planning only. They are not a quote, a customs ruling or legal advice, and duty rates should always be confirmed with a customs broker.
If your results raise bigger questions, we can help through our supply chain and operations consulting.
Before you trust the numbers
- Formulas assume your inputs are right. Check lead times and usage history first.
- Not every item needs the same rule. ABC/XYZ classification shows where precise rules pay off.
- Some stock should not be reordered at all. Read how to find and clear dead stock.
These tools are not a substitute for reviewing results with the people who know your parts and suppliers.
When a spreadsheet stops being enough
A calculator handles one item at a time. Here is where to go when you have thousands.
Plan every item at once
The Optimization Lab works out reorder points, safety stock and forecasts for your whole item list, from your own data.
Try the live demo or read about supply chain software for small manufacturers.
Get hands-on help
We can set stock targets by item from your demand and lead times, and leave you with a routine to keep them current.
Formulas first, then AI
AI inventory tools run on the same formulas as these calculators. Read AI inventory management for small business and use our free AI data readiness checklist before you buy, or see our AI support services.
Supply chain news tracker
Headlines from three supply chain and logistics publishers, updated live from their feeds.
Supply Chain Dive
SupplyChainBrain
Headlines link to the original publishers.
Contact us to talk through your numbers
Bring your inputs and we will help you check the assumptions and think through the options. We agree the scope with you before any work starts.