The operating expense ratio is operating expenses over effective gross income. Three-quarters of the costs are fixed, so the ratio says as much about occupancy as about management.
There is no universally good operating expense ratio: a good one is lower than comparable buildings measured on the same convention and at the same occupancy. The ratio is operating expenses divided by effective gross income, and on an illustrative 200-unit apartment building it is 40.9 per cent. Because three-quarters of the costs are fixed, the same building, run the same way, shows 44.2 per cent at 85 per cent occupancy and 40.0 per cent at 97.
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Asset managers use the operating expense ratio (OER) to compare buildings in a portfolio, to test a seller's numbers and to set budgets. It is a useful screen and a poor verdict. A high ratio can mean costs are out of control, or that rents are low, or that occupancy has dipped while the tax bill and the payroll stayed where they were. Separating those is the job. The calculation below builds the ratio line by line, then shows how much of it moves with occupancy and how much with nothing more than the way the statement is laid out.
| Input | Value |
|---|---|
| Units and average market rent | 200 at 1,500 a month |
| Physical occupancy | 94% |
| Credit loss, on occupied rent | 1% |
| Other income (parking, fees, utility reimbursement) per occupied unit | 750 a year |
| Property taxes | 430,000 |
| Insurance | 150,000 |
| On-site payroll | 320,000 |
| Contract services (landscaping, security, lifts) | 110,000 |
| General and administrative | 70,000 |
| Management fee, % of EGI | 3.0% |
| Variable costs (repairs, turnover, common utilities) per occupied unit | 1,300 a year |
| Replacement reserves per unit, shown separately | 300 a year |
Gross potential rent = 200 × 1,500 × 12 = 3,600,000
Rent collected = 3,600,000 × 94% × (1 − 1%) = 3,350,160
Other income = 750 × 188 occupied units = 141,000
Effective gross income (EGI) = 3,350,160 + 141,000 = 3,491,160
Fixed costs = 430,000 + 150,000 + 320,000 + 110,000 + 70,000 = 1,080,000
Management fee = 3.0% × 3,491,160 = 104,735; variable costs = 1,300 × 188 = 244,400
Operating expenses = 1,080,000 + 104,735 + 244,400 = 1,429,135
OER = 1,429,135 ÷ 3,491,160 = 40.9%; NOI = 2,062,025, a margin of 59.1%
Excel: =TotalOpex/EGI, with EGI built from rent collected, not from gross potential rent
Expenses are 7,146 a unit against EGI of 17,456 a unit. Fixed costs are 75.6 per cent of the total, and property taxes alone take 12.3 per cent of EGI; strip them out and the ratio is 28.6 per cent, which is how some owners in high-tax jurisdictions present it. Computed on gross potential rent instead of EGI, the ratio is 39.7 per cent, flattering the building by more than a point.
| Occupancy | EGI | Operating expenses | OER | NOI |
|---|---|---|---|---|
| 85% | 3,156,900 | 1,395,707 | 44.2% | 1,761,193 |
| 90% | 3,342,600 | 1,414,278 | 42.3% | 1,928,322 |
| 94% | 3,491,160 | 1,429,135 | 40.9% | 2,062,025 |
| 97% | 3,602,580 | 1,440,277 | 40.0% | 2,162,303 |
From 97 to 85 per cent occupancy the ratio rises 4.2 points with no change in how the building is run. Expenses actually fall slightly, because the management fee and variable costs track occupancy; income falls faster. Comparing this building at 85 per cent with a peer at 97 per cent would mark it down for its leasing, not its cost control. The article on physical and economic occupancy shows how to measure the income side consistently.
Two buildings with identical economics can report very different ratios. Three conventions matter most.
| Presentation | Income | Expenses | OER | NOI |
|---|---|---|---|---|
| Recoveries as income, expenses gross | 1,270,000 | 325,400 | 25.6% | 944,600 |
| Recoveries netted against expenses | 1,000,000 | 55,400 | 5.5% | 944,600 |
Same building, same NOI, ratios of 25.6 and 5.5 per cent. That is why an apartment building's 40.9 per cent tells you nothing about an industrial asset's, and why even two industrial assets should be compared only after checking which presentation each uses.
The common mistake is to set a target ratio, or to accept a broker's benchmark, without fixing occupancy, the denominator and the treatment of reserves and recoveries. A seller's T-12 run at 97 per cent occupancy and without reserves will show a lower ratio than the same building under your ownership at a stabilised 94 per cent with reserves above the line, and that gap is not an operating problem you can fix.
Compute the ratio as operating expenses over EGI, state the treatment of reserves and recoveries, and compare buildings at the same occupancy. On the illustrative building that gives 40.9 per cent, and the useful questions are about the lines, not the ratio: taxes at 12.3 per cent of income, fixed costs at 75.6 per cent of expenses. The free workbook for this case builds the operating budget from the rent roll up, driven by units and rates rather than last year plus a percentage, and the NOI article shows the full statement the ratio comes from. Figures are illustrative, not market benchmarks.
Divide total operating expenses by effective gross income: rent collected after vacancy and credit loss, plus other income. Debt service, capital expenditure and depreciation stay out. On the illustrative 200-unit building, $1,429,135 of expenses over $3,491,160 of EGI gives 40.9 per cent, and the NOI margin is the remaining 59.1 per cent.
Either convention is used, so state which one. Lenders and many appraisers deduct reserves above the line; owners often show them below NOI. On the illustrative building, adding $300 a unit, $60,000 in total, moves the ratio from 40.9 to 42.7 per cent, enough to make a well-run building look worse than a peer reported the other way.
Because tenants reimburse most costs, and how the reimbursements are presented decides the ratio. On an illustrative industrial asset with $1,000,000 of base rent, $300,000 of expenses and $270,000 recovered, the ratio is 25.6 per cent with recoveries shown as income and expenses gross, but 5.5 per cent net. The NOI is $944,600 either way.
This article is one calculation from Real Estate Fund Management. The book takes the same case from first principles to the decision, chapter by chapter, and every figure it prints is a live formula in the free companion workbooks.
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