A day rate is the easiest thing to compare between two quotes and one of the least useful. The model you agree decides who pays for the days nobody counted.
Published 13 August 2026
Both models buy the same work from the same person. The only thing they settle is who pays for the days nobody counted: on a day rate that is you, on a fixed price it is the trade, which is why a trade only quotes one where the scope is clear.
Neither model is generous or mean. They are two answers to one question, which is who pays if this takes four days longer than anyone thought, and a trade who will only work on a day rate for a job with drawings and a specification is telling you something.
Here is the arithmetic that gets skipped. Take the published city averages for a general builder. Ten days in London costs £2,330, against £1,960 in Manchester: a gap of £370 across the whole job. Now let the same job run two days long at the cheaper Manchester rate. That costs £392, more than the entire London premium over ten days.
Negotiating the rate is arguing about the smaller number. A day rate is not a unit of work: two trades on the same rate can take a very different number of days over the same room, and nothing in the rate tells you which one you have hired. Ask how many days they are pricing for, and what happens on the day after that.
Each of the six trade pages on this site ends with a verdict. Side by side the pattern is hard to miss: the more measurable the work, the weaker the case for buying it by the day.
General builder, £150 to £400 a day
Builders carry the largest single labour line on most projects, so the difference between a day rate and a fixed price is measured in thousands rather than hundreds.
Electrician, £220 to £500 a day
Anything with a defined end point prices better as a fixed job: a consumer unit swap, a rewire, the electrics for an extension.
Plumber, £200 to £480 a day
A bathroom or kitchen fit-out has a scope you can write down, so it prices as a fixed job and should.
Tiler, £170 to £350 a day
Ask for a square metre price, not a day rate.
Plasterer, £160 to £350 a day
Get a price per room or per square metre for anything you can measure, and keep a day rate for making good, where the work is scattered and nobody can count it in advance.
Painter and decorator, £127 to £350 a day
Ask for a price per room, with the preparation written out: how many coats, what gets filled and sanded, whether woodwork is included, who moves the furniture.
The dividing line is not the size of the job, it is whether the scope can be written down before anyone starts.
Anything in between belongs in writing before the first morning. The day rates guide linked below lists what the published guides put on each side, with their rule of thumb for work under a day.
None of this needs an argument. It needs one conversation before anyone starts and a note of what you both said. The trades who work this way already prefer it: a written scope protects the person doing the work as much as the person paying for it.
The published bands for six trades, with the source behind every figure, and the full day rate against fixed price section.
What to write down before the first morning, including how changes get priced.
Keep a record of every change agreed on site, so the final invoice holds no surprises.