Your net worth is calculated by totaling up all of your assets and then subtracting all of your debts. Net worth = Assets - Debt.
Here is an example:
Let's say you have a checking account, savings account, and investment account. Truebill will add up the balance of these accounts to make up your total assets. You also have a balance on your credit card, an auto loan, and a few student loans. Truebill will add up the balance on your credit card with the balances left on your auto and student loans to make up your total debt. Then to calculate your net worth, Truebill will take the value of your assets (checking, savings, and investments) and subtract the balance of your debts (credit card, auto loan, and student loans). The final number, displayed on the Summary Tab within the Grow Tab, is your net worth.