To find your overhead rate, divide your total indirect costs by your chosen allocation base (such as direct labor hours, direct labor costs, or total direct costs). The result tells you how much overhead you’re spending for every dollar or hour of productive work. This single number helps you price jobs accurately, understand your true cost structure, and avoid undercharging for your products or services.
The Basic Overhead Rate Formula
The formula is straightforward:
Overhead Rate = Total Indirect Costs ÷ Allocation Base
The numerator is every cost your business incurs that isn’t directly tied to producing a specific product or delivering a specific service. The denominator is whatever measure of productive activity you choose to tie those costs to. The ratio between the two is your overhead rate, usually expressed as a percentage or a dollar amount per unit.
For example, if your business spent $150,000 on indirect costs last year and your team logged 10,000 direct labor hours, your overhead rate is $15 per direct labor hour. If you use direct labor cost as the base instead and your total direct labor cost was $400,000, your overhead rate is 37.5% ($150,000 ÷ $400,000). That means for every dollar you pay in direct labor, you spend about 38 cents on overhead.
What Counts as an Indirect Cost
Indirect costs are expenses you can’t easily assign to one specific project, product, or customer. They keep the business running but don’t belong to any single job. Common examples include:
- Rent and utilities for your office, warehouse, or shop
- Administrative salaries for staff like bookkeepers, HR personnel, and office managers
- Insurance premiums covering general liability, property, or workers’ compensation
- Office supplies and equipment shared across the business
- Depreciation on buildings, vehicles, or machinery not dedicated to one project
- Training costs that benefit the organization broadly
- Travel expenses not attributable to a single project
The key test is whether you can trace a cost directly to a specific job or product. If a cost clearly belongs to one project, like raw materials for a custom order, it’s a direct cost. If it supports the whole operation without belonging to any one job, it’s indirect, and it goes into the numerator of your overhead rate.
How to Choose an Allocation Base
The allocation base is the activity measure you divide your indirect costs by. Picking the right one matters because it determines how overhead gets spread across your jobs or products. The goal is to choose a base that reflects what actually drives your overhead spending. Common options include:
- Direct labor hours: Best when your overhead rises and falls with the number of hours your team works. Service businesses and labor-intensive manufacturers often use this.
- Direct labor costs: Similar logic, but accounts for differences in pay rates. If your senior employees drive more overhead than junior ones, labor dollars may be a better base than labor hours.
- Machine hours: Useful when equipment usage drives most of your overhead, such as in manufacturing facilities where depreciation, maintenance, and energy costs dominate.
- Total direct costs: A broader base that includes labor, materials, and subcontractor costs combined. This is the simplest approach and works when no single cost category dominates your overhead pattern.
There’s no universally correct base. A software consulting firm whose biggest overhead drivers are office rent and project management salaries would reasonably use direct labor hours or labor cost. A machine shop burning through electricity and tooling would lean toward machine hours. Look at your actual cost structure and pick the base that most closely correlates with how overhead accumulates.
Step-by-Step Calculation
Here’s how to work through the calculation from scratch:
Step 1: Gather your indirect costs. Pull together every expense that doesn’t tie directly to a specific job. Use your general ledger or accounting software to total these for the period you’re analyzing, typically a full fiscal year. Using a full year smooths out seasonal fluctuations.
Step 2: Pick your allocation base and total it for the same period. If you’re using direct labor hours, add up every hour your production or billable staff worked on jobs. If you’re using direct labor cost, total the wages and salaries paid for project work. Make sure the time period matches the one you used for indirect costs.
Step 3: Divide. Indirect costs divided by your allocation base gives you the overhead rate. If you divided by hours, you’ll get a dollar amount per hour. If you divided by a cost figure, you’ll get a percentage.
Step 4: Apply the rate to individual jobs. Multiply the overhead rate by each job’s share of the allocation base. If Job A used 200 direct labor hours and your rate is $15 per hour, you’d assign $3,000 in overhead to that job. Add that to the job’s direct costs to see the full cost of completing it.
A Worked Example
Suppose you run a small manufacturing business. Over the past year, you spent $90,000 on factory rent, $30,000 on administrative salaries, $12,000 on insurance, and $18,000 on utilities and maintenance. That totals $150,000 in indirect costs.
Your production team logged 7,500 direct labor hours during the same year. Your overhead rate is $150,000 ÷ 7,500 = $20 per direct labor hour.
Now you’re quoting a new job that will require an estimated 120 direct labor hours. You’d allocate $2,400 in overhead to that job (120 × $20). If the job also has $3,600 in direct labor costs and $1,500 in materials, the total estimated cost is $7,500. You can then set your price above that figure to ensure a profit.
Using Proportional Allocation for Greater Accuracy
The single-rate method works well for many businesses, but it assigns overhead using one flat rate across all jobs. If your jobs vary widely in how they consume resources, a proportional approach can be more accurate.
With proportional allocation, you look at each job’s share of total direct costs and assign that same percentage of overhead. If Job A represents 25% of your total direct costs for the period, it receives 25% of the overhead. This approach tracks each overhead expense in your general ledger and distributes the actual totals across jobs rather than relying on a single blended rate.
Some businesses go a step further with weighted proportional allocation. If you know that labor-intensive jobs consume more overhead than material-heavy ones, you can assign a higher weight to labor costs and a lower weight to materials or subcontractor expenses. For instance, you might apply a weight of 2.0 to field labor and 0.5 to subcontract costs, giving labor-intensive jobs a larger share of overhead. This requires more bookkeeping but produces numbers that better reflect reality.
Predetermined vs. Actual Overhead Rates
Most businesses calculate a predetermined overhead rate at the start of the year using estimated indirect costs and estimated activity levels. This lets you assign overhead to jobs in real time rather than waiting until the year ends to know your true costs. Pricing, quoting, and budgeting all depend on having this number available before the work is done.
At year’s end, you compare your predetermined rate to your actual overhead rate (calculated from real numbers). If the two diverge significantly, you’ve either over-applied or under-applied overhead. A small gap is normal. A large one means your estimates were off, and you should adjust next year’s rate. Reviewing this annually keeps your job costing and pricing accurate over time.
What a Good Overhead Rate Looks Like
There’s no single “good” overhead rate because it varies dramatically by industry. A professional services firm with low material costs and high administrative expenses might carry an overhead rate of 50% or more of direct labor costs. A construction company with large material and subcontractor expenses might target a much lower percentage of total direct costs.
What matters is consistency and context. Track your overhead rate over time to spot trends. A rate that’s climbing year over year without a corresponding increase in revenue signals that indirect costs are growing faster than productive output. That’s a prompt to review your lease terms, staffing levels, software subscriptions, and other overhead categories for expenses you can trim or renegotiate.