Begin with income you can reasonably expect, fixed bills, flexible spending, and a line for irregular costs. Use recent statements to estimate actual spending instead of inventing ideal numbers. A budget calculator can organize the totals, but the useful part is revisiting them.
Check whether money remains after essential expenses and planned savings. If the plan does not balance, adjust a category based on reality rather than hiding the gap. Set a short weekly review and a broader monthly check. Keep a buffer for costs that do not arrive on the same day every month.
A budget is a working plan, not a score of personal discipline.
Akousa