To calculate your home's equity, look up the current market value of your house on a website like Zillow or Redfin. Remember these sites just provide an estimate. Getting your home appraised will give you a more accurate estimate but you will have to pay an appraisal fee.
Take the current market value of your house and subtract from it your current mortgage balance, which you will find on your monthly statement, plus any other loans you might have that use your home as collateral. The number you get is the estimated value of the equity you have in your home.