What an employee
actually costs you.
Salary is the number everyone quotes and roughly four fifths of the answer. Employer National Insurance, the pension and the on-costs of putting somebody on site make up the rest. Every rate is editable. Nothing is sent anywhere.
Why holiday is not a line in this calculator
Most tools of this kind add a figure for holiday, and it is double counting. Statutory holiday is paid time inside the salary you have already entered: the employee is paid for 52 weeks and works about 46 or 47 of them, so the salary already carries it.
What holiday genuinely costs is cover, and only where the work has to continue while the person is away. On a site role that might mean agency labour at a higher rate for five weeks. On an office role it often means nothing measurable. Since that number depends entirely on your business, adding an invented one would make the total look precise and be wrong. Put your own figure in the on-costs box if cover is real for the role you are pricing.
Employment Allowance is per business, not per person
The Employment Allowance reduces an eligible employer's National Insurance bill by up to a set amount each tax year. It is claimed once by the business, not once per employee, so it cannot sensibly be divided into a per-head figure.
The result below shows the gross employer NI and notes the allowance separately. If you employ one person it may cover most of their NI. If you employ twenty it is a fixed reduction against the total, and the marginal cost of the next hire is the full figure shown.
What the on-costs box is really for
This is the box that makes the difference between an office calculator and one written for a contractor, and it is worth populating properly rather than leaving at zero.
For a site-based employee it can include a van and its running costs, fuel, insurance, tools and their replacement, PPE, a phone, CSCS or scheme cards and the training behind them, and any competence renewals the role requires. None of it is optional and all of it recurs. For a firm pricing whether it can afford a hire, this is frequently the number that changes the answer.
What this does not do
It does not calculate what the employee takes home, which is a different question involving their income tax and their own NI. It does not handle salary sacrifice, apprenticeship levy, company car benefit, or NI reliefs for particular categories of employee. It is not tax advice, and the rates supplied are defaults checked on the date shown rather than a live feed.
What it is for is the question a director actually asks before a hire: if I pay somebody this, what does it cost the business. For that, the three lines below are most of the answer.