Calculate your rota wage bill

Multiply each employee's contracted hours per week by their hourly rate to get their individual weekly cost. Sum all employees to get the total weekly wage bill. For example, five staff each working 37.5 hours at £13/hr gives a weekly wage bill of 5 × 37.5 × £13 = £2,437.50. Remember this is gross pay — you will also need to account for employer National Insurance contributions (13.8% on earnings above the Secondary Threshold) and pension contributions separately.

For shift workers, calculate the cost per shift first: multiply the shift length in hours by the hourly rate for each employee covering that shift. Then sum across all shifts in the period. If employees work different patterns each week (for example, compressed hours or rotating shifts), use the actual hours scheduled per week rather than a fixed contracted hours figure. Tools like TimeTally can track actual hours against the planned rota automatically.

The wage bill typically refers to gross pay — the total wages paid to employees before deductions. It does not include employer costs such as employer National Insurance contributions (currently 13.8% on earnings above the Secondary Threshold of £5,000/year), employer pension contributions (minimum 3% under auto-enrolment), or other on-costs such as training, uniforms, or recruitment. Total employment cost is typically 20–25% higher than the gross wage bill alone.

If employees work hours beyond their contracted threshold and are entitled to overtime pay, you must include the overtime premium in your rota cost calculation. For example, if an employee works 5 hours of time-and-a-half overtime at a base rate of £13/hr, the overtime cost is 5 × £13 × 1.5 = £97.50, not 5 × £13 = £65. UK law does not require employers to pay a premium for overtime, but if the employment contract specifies an overtime rate, it must be honoured. The average hourly rate across all hours worked must also never fall below the National Minimum Wage.

The National Minimum Wage (NMW) for workers aged 21 and over is £12.21 per hour from April 2025, which remains in effect in 2026. Separate rates apply to younger workers and apprentices: £10.00/hr for workers aged 18–20, £7.55/hr for workers aged 16–17, and £7.55/hr for apprentices in their first year or aged under 19. Employers must ensure that total pay divided by total hours worked — including any unpaid overtime — never falls below the applicable NMW rate. HMRC can impose back pay and financial penalties for non-compliance.

Under the Working Time Regulations 1998, all workers are entitled to a minimum of 5.6 weeks' paid holiday per year (equivalent to 28 days for someone working 5 days per week). For rota workers with variable hours, holiday pay is calculated as an average of earnings over the previous 52 weeks worked. This means your effective annual wage cost is higher than 52 weeks of contracted pay: multiply weekly wage cost by 52, then add the cost of holiday pay on top — approximately an additional 12.07% of pay for workers receiving the statutory minimum.

Gross pay is what an employee receives before income tax and National Insurance deductions. Total employment cost (sometimes called the 'on-cost') is what the employer actually pays and is significantly higher. It includes: gross pay, employer National Insurance contributions (13.8% on earnings above the Secondary Threshold of £5,000/year), employer auto-enrolment pension contributions (minimum 3% on qualifying earnings), and any other contractual costs such as enhanced sick pay or allowances. A quick estimate is to add approximately 20–25% to the gross wage bill to arrive at total employment cost.

A 4-on-4-off rota involves employees working four consecutive shifts followed by four days off, repeating continuously. Over a 52-week year, an employee on 4-on-4-off works approximately 182.5 days (365 ÷ 2). If each shift is 12 hours, the annual hours worked are approximately 182.5 × 12 = 2,190 hours. Weekly cost is harder to express as a simple number because hours vary week to week, so calculate annual cost directly: 2,190 hours × hourly rate. Divide by 12 for a monthly figure or by 52 for a weekly average.

The cost of staffing a shift depends on: the number of employees required to cover the shift, the length of the shift in hours, and each employee's hourly rate. Multiply hours × rate for each employee covering the shift, then sum across all of them. For example, a 10-hour shift covered by three employees at £13/hr costs 3 × 10 × £13 = £390 in gross wages. Remember to factor in employer NI and pension contributions for the true cost to the business.

Zero-hours contract workers are only paid for hours actually worked, so their cost varies week to week based on the hours allocated on the rota. This makes zero-hours workers more flexible in cost terms — you only incur wage costs for shifts that are rostered and worked. However, they are still entitled to National Minimum Wage for all hours worked, holiday pay accrued at 12.07% of pay (or the 52-week average pay method), and employer National Insurance and pension contributions apply in the same way as for contracted staff. Tracking actual hours for zero-hours workers is essential to ensure accurate pay calculations.