Last updated: May 2026
Quick Answer
The Operating Expense Ratio (OER) measures what percentage of your total revenue is consumed by operating expenses. It is calculated by dividing your Operating Expenses by your Total Revenue, then multiplying by 100. A ratio of 60-80% is typical for most healthy businesses.
Key Takeaways
- ✓ OER Formula = (Operating Expenses ÷ Total Revenue) × 100
- ✓ Operating Expenses (OpEx) include rent, salaries, and marketing, but exclude COGS, interest, and taxes.
- ✓ A lower ratio indicates higher operational efficiency and more room for net profit.
- ✓ Investors look closely at OER to see if a business is scaling efficiently (revenue should grow faster than OpEx).
What Exactly Is the Operating Expense Ratio?
The Operating Expense Ratio (OER) is a fundamental financial metric that shows how much it costs to run your core business operations relative to the money you bring in. It acts as a direct measure of management efficiency.
If your OER is 70%, it means that for every $1.00 of revenue you generate, you spend 70 cents just keeping the lights on, paying non-production staff, and marketing your product. This leaves only 30 cents to cover the actual cost of the goods (COGS), pay taxes, service debt, and finally generate net profit.
What Counts as an Operating Expense?
To calculate OER accurately, you must know what to include and what to exclude. Operating Expenses (often called SG&A — Selling, General, and Administrative expenses) are the day-to-day costs of running a business not tied directly to producing a specific product.
Include in OpEx:
- • Rent and utilities
- • Marketing and advertising
- • Administrative/sales salaries
- • Software subscriptions
- • Office supplies and insurance
Do NOT Include:
- • Cost of Goods Sold (COGS)
- • Direct labor for manufacturing
- • Interest payments on debt
- • Income taxes
- • Capital expenditures (buying equipment)
How to Calculate OER (Example)
Imagine a digital marketing agency with the following annual numbers:
- Total Revenue: $1,200,000
- Rent & Utilities: $100,000
- Staff Salaries: $600,000
- Marketing: $140,000
Their total Operating Expenses equal $840,000. To find the ratio: ($840,000 ÷ $1,200,000) × 100 = 70%. This means 70% of their revenue goes toward operating the agency.
4 Ways to Improve Your OER
If your ratio is creeping too high, it means your costs are growing faster than your sales. Here is how to fix it:
- Renegotiate Fixed Costs: The fastest way to lower OpEx is to reduce fixed overhead. Renegotiate your lease, switch insurance providers, or audit your software subscriptions for unused licenses.
- Automate Administrative Tasks: Administrative salaries are often the largest component of OpEx. Implementing AI tools for customer service or automated accounting software can reduce the need to hire more admin staff as you scale.
- Increase Pricing: If you raise your prices by 10% without losing customers, your Total Revenue increases while your OpEx stays exactly the same. Your OER will immediately drop.
- Shift to Performance-Based Marketing: Instead of paying flat retainers for marketing, shift to affiliate marketing or commission-based sales structures.
Frequently Asked Questions
What is a good operating expense ratio?
It varies heavily by industry, but generally 60-80% is typical. A lower ratio is always better as it means more revenue converts to profit. For example, highly scalable software companies often target under 65%.
What counts as an operating expense?
Operating expenses (OpEx) include rent, utilities, administrative salaries, marketing, insurance, and office supplies. Essentially, it is the cost of running the business day-to-day.
What is NOT included in operating expenses?
Do not include the Cost of Goods Sold (COGS), direct manufacturing labor, interest payments on debt, income taxes, or large capital expenditures (like buying a building).
Is OER the same as Profit Margin?
No. The Operating Expense Ratio measures your overhead costs. Profit Margin measures what is left over after ALL costs (including COGS, taxes, and interest) are paid.
Why is my OER increasing?
An increasing OER means your expenses are growing faster than your sales. This usually happens during rapid expansion (hiring ahead of revenue) or when fixed costs (like rent) increase while sales stagnate.