Units Started and Completed Formula

This calculator works out the number of units a manufacturer started and fully completed during a period, a key figure in process costing. You enter the beginning work-in-process (WIP) units, the units started during the period, and the ending WIP units, and you get the units started and completed, along with the total units completed. The formula is simply: Units Started and Completed = Units Started – Ending WIP Units.

Formula

The formula for units started and completed is:

Units Started and Completed = Units Started – Ending WIP Units

Where:

• Units Started = number of units that began production during the period (units)
• Ending WIP Units = number of units still in process at the end of the period (units)

This formula assumes that all units in ending WIP were started during the current period, which is true when there is no beginning WIP or when the beginning WIP is tracked separately. In a process costing system, the units started and completed are the portion of finished goods that were both started and finished in the same accounting period.

Worked Example

Using the default values from the calculator:

• Beginning WIP units = 100
• Units started during period = 1000
• Ending WIP units = 200

Step 1: Apply the formula for units started and completed:

Units Started and Completed = 1000 – 200 = 800 units

Step 2: Calculate total units completed (including those from beginning WIP):

Total Units Completed = Beginning WIP + Units Started – Ending WIP = 100 + 1000 – 200 = 900 units

The calculator shows 800 for units started and completed and 900 for total units completed, matching the manual calculation.

Why This Number Matters in Cost Accounting

In process costing (used by manufacturers of homogeneous products like chemicals, food, or textiles), managers need to know how many units were fully processed during a period. The units started and completed figure is essential for calculating the cost per equivalent unit, because it separates units that were already partially done at the start from units that went through the entire process in the current period.

For example, if a paint manufacturer starts the month with 500 gallons half-finished, starts 10,000 gallons, and ends with 800 gallons in process, the units started and completed are 9,200 gallons. Those 9,200 gallons received all materials and conversion costs in the current month, while the beginning WIP only received the remaining conversion costs.

Knowing this number helps with:

• Calculating cost per equivalent unit accurately
• Valuing ending work-in-process inventory
• Preparing production cost reports
• Identifying bottlenecks or unusual production patterns

How to Use the Calculator

Enter the three required inputs:

1. Beginning WIP units – units in process at the start of the period (from the previous period’s ending WIP)
2. Units started – units that began production during the current period (from production reports)
3. Ending WIP units – units still in process at the end of the period (from physical count or estimates)

The calculator outputs:

• Units started and completed – the main answer, shown as the headline result
• Total units completed – includes units from beginning WIP that were finished, plus units started and completed

All results are in the same unit you enter (units, dozens, gallons, etc.). The calculator does not convert between units of measure.

Common Mistakes and Misconceptions

Confusing “units started� with “units started and completed.� Units started is the total that entered production; units started and completed is a subset of that – those that also finished in the same period. The difference is the ending WIP.

Forgetting beginning WIP when calculating total completed. Many people only subtract ending WIP from units started, which gives units started and completed, not total completed. To get total completed, you must add beginning WIP.

Using the formula when beginning WIP exists and you want only current-period work. The simple formula works for units started and completed, but for cost calculations you must also account for the degree of completion of beginning WIP. That requires equivalent units, not just physical units.

Rounding errors. If you round intermediate numbers (like equivalent units) too early, the final cost per unit can be off. Keep full precision until the final step.

Limitations of the Formula

The formula assumes that all ending WIP units were started during the current period. If there is beginning WIP and you want to know how many of the completed units came from beginning WIP, you need additional information about the stage of completion of the beginning WIP. The formula also does not account for spoiled or defective units – those are usually treated separately in cost accounting. For process costing with multiple departments, you would apply this calculation in each department separately, because each department has its own beginning and ending WIP.

Finally, the formula only gives physical unit counts, not costs. To assign costs, you must multiply the units by the cost per equivalent unit, which requires separate calculations for materials and conversion costs.

Frequently Asked Questions

What is the difference between units started and completed and total units completed?

Units started and completed are only those units that both began and finished production in the same period. Total units completed includes those plus any units that were in beginning WIP and were finished during the period. For example, with 100 beginning WIP, 1000 started, and 200 ending WIP, units started and completed = 800, but total completed = 900.

Can I use this formula if there is no beginning WIP?

Yes. If beginning WIP is zero, then units started and completed equals total units completed, and the formula becomes: Units Completed = Units Started – Ending WIP. This is a common situation in a new production line or a period that starts with no inventory in process.

How do I calculate equivalent units of production?

Equivalent units are calculated by multiplying the number of physical units by the percentage of completion for each cost component (materials, labor, overhead). For units started and completed, they are 100% complete, so equivalent units equal physical units. For ending WIP, you multiply the physical units by the percentage complete. This is separate from the units started and completed formula.

What if some ending WIP units were actually started in a previous period?

That cannot happen if you define the period correctly. Ending WIP is the inventory at the end of the period; those units were started at some point. If they were started in a previous period, they would have been part of beginning WIP of the current period. The formula assumes all ending WIP units were started during the current period, which is standard in process costing.

Why is the units started and completed number important for cost per unit?

Because these units received all costs (materials, labor, overhead) in the current period, they are the benchmark for a fully processed unit. To find the cost per equivalent unit, you divide total costs by the equivalent units, which includes units started and completed plus the equivalent work done on beginning and ending WIP. Without isolating units started and completed, you would over- or under-state the cost per unit.

Related

• Huawei Code Calculator: What It Really Does
• Huawei Unlock Code Calculator: How It Works
• Java Calculator Code: How to Build One

in b | Beginning WIP units | units | 100 | 0
in s | Units started during period | units | 1000 | 0
in e | Ending WIP units | units | 200 | 0
out u | Units started and completed | units | s - e | 0
out c | Total units completed | units | b + s - e | 0