Inventory Calculator
Work out what your stock is worth, how fast it turns over, and when to make or order more.
Finished stock is money that has already been spent and has not come back yet, so how much of it you hold and how fast it moves decides whether the business has cash. This calculator values the stock, works out the turnover ratio and the days of stock, and sets a reorder point from the lead time. It is the tool to reach for when a workshop is full of products and the bank account is empty.
At a glance
- What you enter
- Stock at the start of the period, Stock on hand now, Units sold in the period, Days in the period, Cost to make one unit, Selling price per unit, Lead time to restock, Safety stock
- What you get
- Stock value at cost, Stock value at retail, Profit tied up in stock, Stock turnover, Days of stock on hand, Months of stock, Units sold per day, Revenue for the period, Gross profit for the period, Cost of goods sold for the period, Reorder point, Safety stock units, Stock against the reorder point, Time to make or order more, Stock value as a share of the period revenue, Suggested stock ceiling, Turnover band
- Formula shown
- Yes, every step, right below your results.
- Cost and privacy
- Free, no account needed, and nothing you type is stored.
See worked examples ↓ Read the FAQ ↓ Share this calculator ↓
Results are estimates for general information only, always verify with a professional or official source before acting on them.
How to use the Inventory Calculator
- 1 Enter Stock at the start of the period, Units on hand at the beginning. Leave at zero to use only the closing stock.
- 2 Enter Stock on hand now, Units of finished goods you are holding right now.
- 3 Enter Units sold in the period, Total sold over the period you are measuring, usually a year or a quarter.
- 4 Enter Days in the period, Three hundred and sixty five for a year, ninety for a quarter.
- 5 Enter Cost to make one unit, Materials, labour and overhead. Not the selling price.
- 6 Enter Selling price per unit
- 7 Enter Lead time to restock, Days from deciding to make or order more to having it ready to sell. Zero when you make to order instantly.
- 8 Enter Safety stock, Extra days of cover for a busy spell or a slow delivery. Two weeks is a fair buffer for a small maker.
- 9 Press Calculate. You get Stock value at cost, Stock value at retail, Profit tied up in stock, Stock turnover, Days of stock on hand, Months of stock, Units sold per day, Revenue for the period, Gross profit for the period, Cost of goods sold for the period, Reorder point, Safety stock units, Stock against the reorder point, Time to make or order more, Stock value as a share of the period revenue, Suggested stock ceiling, Turnover band, and every intermediate step stays visible under "How is this calculated?"
- 10 Change one number at a time to see what moves the result, that is usually the most useful thing a calculator can tell you.
Worked examples
Real numbers run through this calculator. Open any example to load it into the form above and change it.
A year of sales with forty units in stock
A small range selling 120 units a year and holding 40.
You enter
- Stock at the start of the period
- 0
- Stock on hand now
- 40
- Units sold in the period
- 120
- Days in the period
- 365
- Cost to make one unit
- $18.00
- Selling price per unit
- $45.00
- Lead time to restock
- 7
- Safety stock
- 14
You get
- Stock value at cost
- $720.00
- Stock value at retail
- $1,800.00
- Profit tied up in stock
- $1,080.00
- Stock turnover
- 6.00
- Days of stock on hand
- 121.67 days
- Months of stock
- 4.00
- Units sold per day
- 0.33
- Revenue for the period
- $5,400.00
- Gross profit for the period
- $3,240.00
- Cost of goods sold for the period
- $2,160.00
- Reorder point
- 7
- Safety stock units
- 5
- Stock against the reorder point
- 5.79
- Time to make or order more
- 0
- Stock value as a share of the period revenue
- 13.3%
- Suggested stock ceiling
- 15
- Turnover band
- 1
A stock value of 720 dollars at cost, a turnover of 6 and 122 days of stock, which is slower than it looks from the turnover alone.
A quarterly check
Ninety days, thirty units sold, fifteen in stock.
You enter
- Stock at the start of the period
- 25
- Stock on hand now
- 15
- Units sold in the period
- 30
- Days in the period
- 90
- Cost to make one unit
- $22.00
- Selling price per unit
- $55.00
- Lead time to restock
- 14
- Safety stock
- 10
You get
- Stock value at cost
- $330.00
- Stock value at retail
- $825.00
- Profit tied up in stock
- $495.00
- Stock turnover
- 1.50
- Days of stock on hand
- 45.00 days
- Months of stock
- 1.48
- Units sold per day
- 0.33
- Revenue for the period
- $1,650.00
- Gross profit for the period
- $990.00
- Cost of goods sold for the period
- $660.00
- Reorder point
- 8
- Safety stock units
- 4
- Stock against the reorder point
- 1.88
- Time to make or order more
- 0
- Stock value as a share of the period revenue
- 20.0%
- Suggested stock ceiling
- 14
- Turnover band
- 3
A turnover of 1.5 for the quarter, which annualises to about six, and a reorder point of eight units.
A workshop full of unsold stock
Two hundred units held against 150 sold in the year.
You enter
- Stock at the start of the period
- 180
- Stock on hand now
- 200
- Units sold in the period
- 150
- Days in the period
- 365
- Cost to make one unit
- $16.00
- Selling price per unit
- $42.00
- Lead time to restock
- 21
- Safety stock
- 21
You get
- Stock value at cost
- $3,200.00
- Stock value at retail
- $8,400.00
- Profit tied up in stock
- $5,200.00
- Stock turnover
- 0.79
- Days of stock on hand
- 486.67 days
- Months of stock
- 15.99
- Units sold per day
- 0.41
- Revenue for the period
- $6,300.00
- Gross profit for the period
- $3,900.00
- Cost of goods sold for the period
- $2,400.00
- Reorder point
- 18
- Safety stock units
- 9
- Stock against the reorder point
- 11.59
- Time to make or order more
- 0
- Stock value as a share of the period revenue
- 50.8%
- Suggested stock ceiling
- 21
- Turnover band
- 3
A stock value of 3,200 dollars, a turnover of 0.79 and two and a half years of stock. This is the profile of a range that needs cutting.
Guides that go with it
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Frequently asked questions
What is a good stock turnover for a small maker?
Between two and six times a year for most handmade ranges, which is a stock that lasts from two to six months. Below two, the stock is absorbing cash faster than it returns it and the range probably has items that should be discontinued. Above six, the maker is often making to order, which is the healthiest position for a small business because it holds the least cash in finished goods.
How much stock should I hold?
As little finished stock as the sales pattern allows. A reasonable ceiling is about thirty days of sales plus a safety buffer, which is enough to cover a busy spell without tying up a season of cash. Components are different: hold more of the materials that are slow to obtain or are bought in minimum quantities, because a shortage of one component stops the whole range rather than one item.
Should stock be valued at cost or at selling price?
At cost, for any decision about the business. Valuing stock at the selling price counts profit that has not happened and hides how much cash is tied up. The retail value is worth knowing as the potential, which is why this calculator shows both, but a bank, an accountant or a decision about whether to make more should be looking at the cost figure.
What is a reorder point and do I need one?
It is the stock level at which you start making or ordering more, set so the new stock is ready before the old runs out. It is the daily sales rate multiplied by the lead time, plus a safety buffer. A maker with no lead time needs only the buffer, because stock can be made the same day. A maker ordering components with a three week lead time needs three weeks of sales plus the buffer, or the range goes out of stock.
Why is my cash low when my stock is full?
Because the stock is the cash. Every finished item on the shelf is material and labour that has been paid for and not yet sold, so a workshop full of products is a business with its money in a cupboard. The way out is to sell down the stock before making more, to discontinue the items that are not moving, and to move towards making to order for anything with a long lead time on the components.