Plantwide Predetermined Overhead Rate Calculator

Enter Plantwide Overhead Details

Job or Batch Name

Allocation Base Name

Estimated Manufacturing Overhead

Estimated Total Allocation Base

Actual Overhead Incurred

Actual Total Plant Activity

Job Activity Used

Direct Materials Cost

Direct Labor Cost

Units In Job

Target Markup Percent

Decimal Places

Example Data Table

Scenario	Estimated Overhead	Estimated Base	Job Base	Rate	Job Applied Overhead
Machine shop	125,000	25,000 machine hours	480 machine hours	5.00	2,400.00
Labor shop	96,000	12,000 labor hours	350 labor hours	8.00	2,800.00
Assembly batch	210,000	70,000 units	1,200 units	3.00	3,600.00

Formula Used

Plantwide predetermined overhead rate = Estimated total manufacturing overhead ÷ Estimated total allocation base.

Job applied overhead = Plantwide predetermined overhead rate × Job activity used.

Total plantwide applied overhead = Plantwide predetermined overhead rate × Actual total activity.

Overhead variance = Actual overhead incurred − Total plantwide applied overhead.

Total job manufacturing cost = Direct materials + Direct labor + Applied overhead.

Target price = Total job manufacturing cost + Markup amount.

How To Use This Calculator

Enter the estimated manufacturing overhead for the full plant.

Enter the expected total activity for the same period.

Select the allocation base that best matches overhead behavior.

Add actual overhead and actual activity for variance review.

Enter job activity, materials, labor, units, and markup.

Press the calculate button. The result appears above the form.

Use CSV or PDF buttons to save the completed report.

What This Calculator Does

A plantwide predetermined overhead rate gives one factory rate for assigning manufacturing overhead to products, jobs, batches, or services. It is useful when departments share similar cost behavior. It also helps small manufacturers avoid a complex departmental system. The calculator combines estimated overhead with an estimated allocation base. Then it applies that single rate to actual activity and job activity. The result shows rate, applied overhead, total job cost, overhead per unit, and overapplied or underapplied overhead.

Why The Rate Matters

Managers need fast cost estimates before production ends. Actual overhead is usually unknown until invoices, payroll adjustments, maintenance costs, and utility bills are closed. A predetermined rate solves that timing problem. It lets teams quote prices, plan margins, compare jobs, and review production efficiency during the period. The rate is still an estimate. So the calculator also compares applied overhead with actual overhead incurred.

Using Strong Inputs

Better inputs create better cost signals. Estimated overhead should include indirect labor, factory rent, depreciation, insurance, supervision, repairs, and factory utilities. The allocation base should match the main cost driver. Direct labor hours may fit labor focused work. Machine hours may fit automated production. Direct labor cost may work when wages drive support costs. Units can work only when products are similar.

Reading The Results

The plantwide rate is the estimated overhead divided by the estimated base. Applied overhead is the rate multiplied by activity used. If actual overhead is higher than applied overhead, overhead is underapplied. If applied overhead is higher than actual overhead, overhead is overapplied. A large gap may mean the estimate was weak, the base changed, or spending moved away from the plan.

Practical Review Tips

Use the result as a planning guide, not a perfect audit figure. Review the rate each period. Compare it with departmental rates when products use resources differently. Export the CSV for spreadsheet review. Download the PDF for job files, internal notes, or pricing support. Keep assumptions clear. That makes overhead decisions easier to defend. For advanced review, test several bases. Small changes can shift product margins. Save each scenario with a clear name. Then compare rates before choosing the most realistic costing approach for management review each month.

FAQs

What is a plantwide predetermined overhead rate?

It is one estimated factory overhead rate used for all jobs or products. It assigns overhead before actual costs are fully known.

Which allocation base should I use?

Use the base that best drives overhead. Machine hours fit automated work. Labor hours fit labor focused production.

Why use estimated overhead instead of actual overhead?

Actual overhead is often known after the period ends. Estimated overhead allows faster pricing, costing, planning, and job review.

What does underapplied overhead mean?

Underapplied overhead means actual overhead is higher than applied overhead. More cost occurred than the rate assigned.

What does overapplied overhead mean?

Overapplied overhead means applied overhead is higher than actual overhead. The rate assigned more overhead than actually occurred.

Can I use direct labor cost as the base?

Yes. It works when support costs move closely with wage spending. It may be weak for highly automated production.

Is a plantwide rate always accurate?

No. It is simple and useful, but it can distort costs when departments use resources very differently.

Can this calculator help with job pricing?

Yes. It estimates applied overhead, total job cost, cost per unit, markup, and target selling price.