The salary on a job offer is not what an employee costs. Employer NI, pension, benefits, and on-costs add 20-25% on top of every salary. Most SME owners do not include these in their pricing, budgeting, or hiring decisions. This tool does.
Real inputs. Real outputs. See exactly what you get before you commit to anything.
This is a live preview of the Headcount Cost Modeller — the same tool available to all subscribers.
Subscribe to access →Every tool generates a downloadable PDF report — structured like a professional consultant's analysis, built from your actual data. Below is an example using dummy data.
When a business owner hires someone at £35,000 per year, the actual cost to the business is not £35,000. It is closer to £42,000 once employer National Insurance, pension contributions, and other employment on-costs are included. That gap — roughly 20-25% depending on salary level and benefit structure — is one of the most consistently underestimated costs in small business.
→ Employer ni calculator uk 2025
This underestimation has practical consequences. If your pricing is based on salary costs rather than fully-loaded employment costs, you are systematically underpricing your services. If your budget uses salary figures rather than total employment costs, your overhead projections are understated. If your hiring decisions are made without calculating the revenue each role needs to generate to justify its cost, some of your hires will never pay for themselves.
The Headcount Cost Modeller fixes all three problems in one tool.
From April 2025, UK employer National Insurance increased from 13.8% to 15%, and the secondary threshold — the salary level above which NI applies — fell from £9,100 to £5,000 per year. This combination means that for a typical SME employee earning £30,000, employer NI costs increased from approximately £2,882 per year to £3,750 per year. For a business with 10 employees at this level, the total additional NI burden is approximately £8,680 per year — an increase that arrived with limited transition time.
The Headcount Cost Modeller applies the current NI rate (15%) and threshold (£5,000) automatically, so your calculations reflect the actual current cost rather than the pre-April 2025 figures that many tools and spreadsheets still use.
The most commercially useful output of the headcount tool is not the cost figure — it is the revenue required to justify the cost at your target gross margin. If a fully-loaded role costs £46,000 per year and your gross margin is 20%, that role needs to generate at least £230,000 in revenue before it contributes a single pound of net profit. At a 40% gross margin, the same role requires £115,000 of revenue to break even.
This calculation is essential for making good hiring decisions. A sales hire who costs £45,000 fully loaded but generates £400,000 of new revenue at a 40% gross margin adds £115,000 of net value — an excellent return. A back-office hire who costs the same but enables £100,000 of additional output capacity needs to be evaluated against whether that capacity will actually be used and whether it generates revenue proportionally.
For service businesses — consultants, agencies, contractors, professional services firms — labour cost is the primary input to pricing. If you price based on salary per hour rather than fully-loaded cost per hour, every project is systematically underpriced. The gap between the two can represent 20-25% of actual cost, and it comes directly out of your net margin.
The correct approach is to calculate fully-loaded cost per hour for each role type, add overhead allocation, and then price at a multiple of this figure that generates the required gross margin. The Headcount Cost Modeller gives you the first of these inputs accurately, so the rest of the calculation can be done correctly.
The National Living Wage increases each April. For businesses with employees at or near NLW levels — hospitality, retail, cleaning, care, logistics — this creates a predictable annual cost increase that must be modelled in advance and reflected in pricing before it arrives. A business that waits for the NLW increase to hit before adjusting prices is already behind — the cost has increased but the price has not, and margin has been permanently reduced until a price review occurs.
The tool allows you to model different salary levels and NI rates, so you can run the April impact before it arrives and make pricing or efficiency decisions in advance rather than in reaction.
The Headcount Cost Modeller is included in every LumixAI subscription. £19.99/month. 7-day free trial. Cancel any time.