In preparing a metal fabrication quote there are mistakes that repeat with surprising regularity, whatever the size of the business. They are not slips of attention: they come from settled habits nobody has ever questioned.
1. Forgetting the waste
The material you buy is never the material that ends up in the product: cuts, shaping and offcuts reduce the yield. If the quote works out the cost on the net quantity rather than the gross one (net plus waste), the real material cost is systematically understated — often by 5-15% depending on the process.
2. Applying the margin to the cost instead of the price
Adding 20% to the cost is not the same as having a 20% margin on the selling price. A cost of €100 marked up by 20% gives a price of €120, but the real margin on the price is 16.7%, not 20%. It looks like a small difference and is an enormous one at volume: the correct formula works out the price by dividing the cost by (1 − the margin you want), not by multiplying it.
3. Underestimating installation hours
Production hours in the shop are relatively easy to estimate from a drawing. Installation on site is more variable: access, working height, structural surprises. Treating installation as a fixed line, identical on every job, with no uplift for difficult conditions, is one of the commonest causes of margin eroded after delivery.
4. Not separating delivery from production
Delivery is a pass-through cost with a small mark-up, not a service of the business carrying a full production margin. Blurring the two when working out the overall margin distorts your sense of how profitable the job really was.
5. No buffer for the unexpected
Every job carries some risk: a material that arrives late, a process that takes longer than planned, a change requested mid-build. A percentage buffer on the total cost — typically between 5% and 15% depending on complexity — protects the margin against the commonest surprises, rather than discovering them at the final costing when it is too late.
The common thread
These five mistakes share one cause: quotes built by hand, under time pressure, without a calculation engine that always applies the same correct formulas. The answer is not to work more slowly, but to automate the steps that today get skipped in a hurry.