Rework and Snagging Cost Calculator

Going back to put a job right cost a hundred and eighty in materials and eight hours. Four hundred and eighty-four pounds’ worth, on the invoice.

It really cost eight hundred and sixty.

The difference is the job you did not do. Those eight hours were not spare hours — they were hours another job would have used, and at forty-seven pounds of margin an hour that is three hundred and seventy-six pounds of work that never happened. It appears on no document anywhere, which is exactly why a snag that only cost a couple of hundred in materials routinely turns out to have cost three times that.

So the job made eighty instead of nine hundred and forty. One return trip took ninety-one per cent of the profit.

The displaced work is valued at margin rather than at your charge-out rate, which is the conservative choice: an hour you did not sell did not cost you the full rate, it cost you what an hour actually leaves behind once materials and wages are out. The honest figure is large enough without help.

And there is one limit that points the other way from everything else here, so the page states it plainly rather than burying it. The displaced job is only a cost if you had one. If the diary was empty that week, those hours were not displacing anything and the revisit really did only cost its materials and its wages. A busy trade should read the full figure; a quiet one should read the direct cost and stop there. Both numbers are on the page and it does not choose for you.

There is no multiplier here for what a fault costs at the next stage, or at the customer. That rule has no source anybody can point at and varies by orders of magnitude between industries, so a page built on it would be inventing most of its own answer.

The table spreads your rework rate across every job you price, which is where the number stops being about one bad afternoon and starts being about the business.

It does not tell you how to reduce the rate. Whether the answer is training, checking, better materials or turning down the jobs that always go wrong is not something arithmetic can see — but knowing what the rate costs is usually the missing half of that argument.

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. A snag on a small job and a snag on a big one are not the same, and it is not the size that decides.

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.