To calculate church giving, determine the percentage of income you wish to give according to what your denomination teaches. Add up your monthly income and determine what amount of that equals the percentage you wish to give for the month.
Many churches use the concept of tithes, or ten percent of income, and offerings, or any amount greater than 10 percent you wish to give. If you choose to give an offering, you can choose either a dollar amount or an additional percentage. Add the ten percent to the offering amount to determine the total amount given.
Add together the gross income from any recurring paychecks for the month, if you choose to give what you earn before taxes, or the amount you earn after taxes are subtracted. If you have any accounts that accrue interest each month or any monetary gifts or bonuses coming in, add it to the monthly income. Divide the total of the incoming money by the percentage you chose to give. That number is the amount to give to the church.
Give using a tithing envelope that allows you to write out your personal information, such as your name and address. This is necessary if you want to claim your giving as a tax deduction because the church gives an annual receipt of the amount given for anyone who fills out the envelopes. The receipt is recorded as a tax document by your tax professional when you file your taxes.