Practical guide for UK trades

How to calculate business overhead per working day

A job can cover its materials and labour yet still fail to contribute enough towards the business that made the work possible.

What belongs in overhead

Typical items include vehicle finance and insurance, public liability and tool cover, phone, software, storage, workshop, accountant, advertising, website, office costs, training, memberships and tool replacement.

Use billable days, not every weekday

A sole trader does not usually sell all 260 weekdays. Holidays, sickness, quoting, administration, training, weather, gaps between jobs and unpaid remedial work reduce the days that can carry overhead.

The daily overhead method

Add the normal monthly overhead and divide it by realistic billable working days in that month. Multiply the daily figure by the job duration.

Example: £2,700 monthly overhead ÷ 18 billable days = £150 overhead per billable day. An eight-day job needs to contribute about £1,200.

The percentage method

A simple percentage is faster, but it can distort very material-heavy or labour-heavy work. Review it against the detailed daily method periodically so the shortcut remains grounded in the business.

Overhead is not profit

Overhead pays the cost of operating. Profit is what remains after the job and business costs. Combining them hides whether the company is actually rewarding the owner for the risk and responsibility.

Use your own figures

The guide explains the decision. The calculator shows what that decision does to a real job.

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