Break-Even and Margin of Safety Calculator

On the figures this ships with, the business breaks even at 149 units a month. At 200 it needs a second van, and it goes straight back into loss until 215.

That is not an unusual case. It is what happens to nearly every small business that grows, and no break-even calculator shows it, because they all assume the fixed costs stay fixed. They do not — they step, at the volume where you need another person, another oven, another van, a bigger unit.

So this page has a box for the step, and it is the box that changes the answer. With one step there are two break-even points and a stretch of losses in between, which means a business can grow straight through profitability and out the other side while everybody is still quoting the figure from before.

If you are sitting inside that band right now, the page says so, tells you how many more sales a month it takes to get out, and points out the part that makes it so disorienting: the loss started on the day business got better.

The table shows profit at every volume with the step and both break-even points marked, so the dip is something you can look at rather than something you have to be told about.

It also leads on margin of safety rather than on the break-even point itself. The point tells you where the line is. The margin tells you how far above it you are — the share of your sales that could vanish before you stopped making money — which is the question that was actually being asked.

One product at a time, on purpose. A break-even across a mixed range depends on the mix of what you sell staying the same, and it does not.

Save as many versions as you like and put any two side by side, figure against figure, with the better one on each line marked and the difference in its own column. That screen is the one that decides things, and it is the part a free calculator cannot do at all. Two products, or the same product before and after a price change.

One HTML file. No account, no subscription, no internet needed. Opens on Windows, Mac and Android; the readme explains the extra step on iPhone and iPad, where Apple blocks JavaScript in downloaded files and every tool of this kind is affected.

Everything lives in your browser on your device. Nothing is uploaded, which is why it works offline and why nobody else can see your figures — and it also means clearing your browsing data deletes it. The tool does not pretend otherwise: the header shows how long since your last export at all times, turns amber after three days and red after seven, and export is one click that produces a plain file you keep.