How do you calculate staff turnover as a percentage?

Take the total number of people employed during the year divided by the current number of employees. Subtract 1. Multiply by 100. So if you issued 75 W-2's and had 50 employees: 75/50=1.5, 1.5-1=.5, .5*100=50% turnover. You might need to adjust this calculation for certain factors, such as seasonal employees. If you added 10 people each year for a short period of time, you would want to subtract the seasonal employees before doing the calculation. If you found that you had 12 seasonal people amongst the 75 W-2's, then you had a 20% turnover of seasonal staff.