Contract / permanent salary calculator
Given a salary, find the day rate that matches it cost for cost, or work the other way round. Every assumption behind the arithmetic, billable days, employer NI, pension and IR35 status, is visible and yours to change.
Holiday and bank holidays are accounted for here, by reducing billable days, not as a separate cost line below.
Assumptions (2025/26 rates - all editable)
Result
£318 / day
Illustrative cost-equivalence arithmetic, not tax or IR35 advice. Outside IR35 assumes a genuine B2B engagement where employer NI and pension don't apply directly, so the day rate is loaded to match total employer cost; inside IR35 assumes those costs are deducted from the contract value before you're paid, rather than added on top by the client.
Want to see what your discipline actually pays before you run these numbers? Check the UK Engineering Salary Survey.
Want a second opinion on a specific offer or contract? Talk to us.