Knowing your monthly income gives you important information you need to work up a personal budget. It will allow you to calculate how much you can spend on rent or a mortgage, utilities, a car payment, insurance and other daily living expenses. From your hourly wage or yearly salary, you can figure out your monthly income and predict the amount of future pay-cheques, which is also essential information in planning when to pay upcoming bills.

Multiply your hourly wage by the number of hours you work in a week to get your weekly pay. Then, multiply this number by 52 -- the number of weeks in a year. Divide the result by 12 -- the number of months in a year. For example, if you make £8 an hour and work 30 hours week, you earn £1,040 a month (£8 x 30 = £240, £240 x 52 = £12,480, £12,480/12 = £1,040).

Multiply your weekly earnings by four -- the average number of weeks in a month -- to get a rough estimate of your monthly earnings. This method will help you budget conservatively. For example, if you earn £240 a week, then your ballpark monthly earnings are £960.

Divide your yearly salary by 12. This gives you your monthly total gross salary -- your total income before taxes and other deductions are taken out. For example, if you make £19,500 a year, your gross monthly salary is £1,625 (£19,500 / 12 = £1,625).