Plimsoll SCMcmksons-aicompany.com/tools/plimsoll/

Plimsoll SCM Supply Chain Management

Safety stock and service levels for supply chain and operations leaders. The Plimsoll line is the mark on a hull between carrying too little and carrying too much.

“Why are we out of stock and overstocked?” Your buffer split into its two causes. When lead times are the bigger one, no amount of demand forecasting will fix it.
“What does 99% availability cost us?” The price of every service level in working capital, and where the curve turns against you.
“Can we take cash out of inventory?” Each lever measured by re-running the whole calculation, with the service promise held fixed.

Free. No signup. Your figures never leave your browser: Copy link carries them inside the link itself, so they reach no server and go only where you send it. Two things do leave: what you type into the chat bubble, and a file you ask to be emailed after a download.

How you buy and hold

The rules that apply to every part

These settings are read by all four tabs, so no two pages can be solving against different assumptions.

The holding rate and the order cost are placeholders, not benchmarks. Both vary enormously by industry and nothing here can verify yours. Put your own numbers in before quoting any of this.

The parts

Showing a sample parts list so you can see how it works. Type over it, or paste your own.
UNIT COST What one unit costs you landed, not what you sell it for. It converts stock into cash and drives the ABC ranking.
DEMAND The average you use in one period. Take the mean of at least the last twelve periods, not the current forecast.
DEMAND ± The standard deviation of that same history. In a spreadsheet: =STDEV(range). It is how much a typical period differs from the average.
LEAD TIME Order placed to stock available, including goods-in and put-away, not the supplier’s quoted transit alone.
LEAD TIME ± The field most tools do not have, and the whole reason for this one. The standard deviation of your actual receipt dates. Pull the last ten or twenty receipts for the part and take =STDEV() of the days taken. Leave it blank only if the supplier is genuinely never early and never late.
DO NOT PAD Enter what actually happened, not a safe number. Padding the inputs hides where the risk is and double-counts the buffer, and computing that buffer is the entire product.
Partcode
Description
Unit costUSD
Demandper week
Demand ±std dev
Lead timeweeks
Lead time ±std dev

One part per line: code | description | unit cost | demand | demand ± | lead time | lead time ±. This box and the rows above are the same data. Editing either updates the other.

Your buffers

What service costs

The price of every service level, in working capital

Each level is solved by re-running the whole calculation, not by scaling one answer. The bend in this curve is the point of it.

Analysis & Recommendation

What to do about it, and what each move is measured to be worth

This updates on its own whenever you change anything on the other tabs. It is never showing you advice about a plan you have already changed.

Definitions

 

Ticked entries re-derive their own formula at page load, independently of the engine, and compare. A definition nobody verifies is only a comment.

Plimsoll SCM · a CMK Sons Labs operations tool · everything computed in your browser