Plan revenue, expenses, contingency buffer, net profit, and category allocation for your business budget
| Expense ratio | Category | What it means |
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| Category | Amount | % of expenses | % of revenue |
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| Metric | Amount | Notes |
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Founder & CEO, Toolraxy
Faiq Ur Rahman is a web designer, digital product developer, and founder of Toolraxy, a growing platform of web-based calculators and utility tools. He specializes in building structured, user-friendly tools focused on health, finance, productivity, and everyday problem-solving.
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This business budget calculator helps you plan revenue, category-level expenses, contingency, tax, and net profit in one view. Enter revenue and seven expense categories, set a contingency buffer, and see profit margin and expense ratio instantly. It’s built for founders, operators, and finance teams who need a fast budget draft. 45+ currencies supported. Nothing gets uploaded.
Most budgets fail at the category level. You can guess total expenses, but unless you break them into fixed costs, payroll, variable costs, marketing, operations, R&D, and other, you won’t know where the money actually goes. This business budget calculator does that breakdown for you. Enter expected revenue for a month, quarter, or year. Add each expense category. Set a contingency buffer as a percentage of planned expenses. Add a tax rate if you want after-tax profit. The tool returns total budgeted expenses, net profit, profit margin, expense ratio, and a category table showing each line as a percentage of expenses and revenue. It also labels your budget health from exceptional to loss-making. Use it to draft a budget, compare scenarios, or check whether a plan can survive a slow quarter.
Pick a currency. The symbol updates on all money inputs. The math stays the same across all 45+ currencies.
Set the budget period. Choose a number and a unit: month, quarter, or year.
Enter expected revenue for that period. This is your top-line target, not last period’s actual.
Fill in the seven expense categories. Fixed costs, payroll, variable costs, marketing, operations, R&D, and other.
Set the contingency buffer. Enter a percentage of planned expenses, typically 5% to 15%.
Optional: enter a tax rate. Leave it at zero for pre-tax profit.
Read the hero tile. It shows total budgeted expenses, with net profit and margin below.
Check the breakdown and summary tables. They show each category as a percentage of expenses and revenue.
The budget math starts with planned expenses, then adds contingency, then subtracts from revenue. Tax applies only when pre-tax profit is positive.
Formula: Planned Expenses = Fixed + Payroll + Variable + Marketing + Ops + R&D + Other
Formula: Contingency Amount = Planned Expenses × (Contingency % ÷ 100)
Formula: Total Budgeted Expenses = Planned Expenses + Contingency Amount
Formula: Pre-tax Profit = Revenue − Total Budgeted Expenses
Formula: Tax = Max(0, Pre-tax Profit) × (Tax Rate ÷ 100)
Formula: Net Profit = Pre-tax Profit − Tax
Formula: Profit Margin = Net Profit ÷ Revenue × 100
Formula: Expense Ratio = Total Budgeted Expenses ÷ Revenue × 100
A few edge cases matter. If revenue is zero, the tool returns zero margins and flags the budget as missing revenue. If pre-tax profit is negative, tax is set to zero, since you don’t pay tax on a loss. Contingency applies to planned expenses, not to revenue, so it scales with your cost base. And the expense ratio can go above 100%, which means you plan to spend more than you earn.
A digital agency planning a monthly budget. Numbers below.
Inputs: Expected revenue $54,800. Fixed costs $8,200. Payroll $22,500. Variable costs $6,400. Marketing $4,100. Operations $2,300. R&D $1,200. Other $900. Contingency 7%. Tax rate 21%.
Step 1 – Planned expenses. 8,200 + 22,500 + 6,400 + 4,100 + 2,300 + 1,200 + 900 = $45,600.
Step 2 – Contingency amount. 45,600 × 0.07 = $3,192.
Step 3 – Total budgeted expenses. 45,600 + 3,192 = $48,792.
Step 4 – Pre-tax profit. 54,800 − 48,792 = $6,008.
Step 5 – Tax. 6,008 × 0.21 = $1,261.68.
Step 6 – Net profit. 6,008 − 1,261.68 = $4,746.32.
Step 7 – Profit margin. 4,746.32 ÷ 54,800 × 100 = 8.66%.
Step 8 – Expense ratio. 48,792 ÷ 54,800 × 100 = 89.04%.
Step 9 – Category percentages. Payroll is 46.1% of expenses and 41.1% of revenue. Fixed costs are 16.8% of expenses and 15.0% of revenue.
Interpretation: The budget sits in the “Tight” tier at an 89% expense ratio. Net profit is $4,746 on $54,800 revenue. That’s a thin margin. Any cost overrun above about 11% of revenue would push the budget into a loss. The contingency buffer helps, but it’s already included in the expense ratio. Focus on either raising revenue or cutting discretionary spend before locking the plan.
Add all planned expense categories, then add a contingency buffer as a percentage of that subtotal. A $45,600 planned base with 7% contingency becomes $48,792. The calculator does this in one step.
Below 50% is exceptional, 50% to 70% is very healthy, and 70% to 85% is healthy. 85% to 95% is tight. Above 95% is break-even territory. Above 100% means your plan spends more than it earns.
Most businesses use 5% to 15% of planned expenses. Use 5% for stable operations and 15% for volatile or seasonal businesses. The calculator accepts any value up to 50%.
Either revenue is too low for the cost base, one category has grown faster than revenue, or contingency and tax are eating into profit. Check payroll as a percentage of revenue first, then variable costs and marketing.
Fixed costs stay the same when revenue changes, like rent and insurance. Variable costs move with sales, like materials and ad spend. Keeping them separate helps you find your break-even point.
Yes, if you draw a regular salary. If you take distributions, those come out of profit, not payroll. Either way, the cost of the owner’s time should appear somewhere in the budget.
Monthly for most small businesses. Compare actuals against the plan, then adjust the next period. Quarterly reviews work for stable operations. Annual budgets alone go stale too fast.
Tax applies only to positive pre-tax profit. A 21% tax rate on $6,008 pre-tax profit gives $1,261.68 in tax and $4,746.32 in net profit. If pre-tax profit is negative, tax is zero.
Run the budget with the lower revenue and the same expenses. Watch the expense ratio. If it crosses 100%, you’re planning a loss. Then cut discretionary spend, delay projects, or lower the contingency buffer.
Yes. Set the period length to 1 or more and pick month, quarter, or year. The math doesn’t change, and the period label flows through the summary table.
The categories are business-focused, but the math works for personal budgets too. Rename categories in your head, or use it as a template for household fixed costs, savings, and discretionary spend.
Any spending on developing new products, testing ideas, or improving existing offerings. Software tools, prototype materials, and contractor time for new features all count. If it’s tied to something you’ll sell later, it belongs in R&D.
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