OEE Calculator

The OEE Calculator computes Overall Equipment Effectiveness from a week of production data. You enter one row per day, and it returns availability, performance and quality, their product as OEE, and the losses behind them expressed both in minutes and in units of lost output.

It also reports Total Effective Equipment Performance, which measures the same fully productive time against the whole calendar rather than against scheduled time.

Read the input grid carefully before entering anything. The last column is rejects, not good pieces. Good count is derived by subtracting rejects from the total count. Entering good pieces there will produce a quality figure that is wrong by a very large margin.

Purpose and model boundary

This model calculates overall equipment effectiveness (OEE) from up to seven production-day rows. It separates planned production time into availability, speed, quality, and fully productive time; reports the aggregate OEE and total effective equipment performance (TEEP); and charts daily availability, performance, quality, and OEE.

It is a descriptive loss model. It does not diagnose root cause, establish the correct ideal cycle time, collect machine data, or define whether a stop is planned or unplanned for a particular operation.

Inputs and units

Each row in Daily_Production_Data contains:

Blank rows are allowed. The grid has a fixed seven-row capacity, and calculations aggregate every populated or zero row.

Governing relationships

For each row, the workbook calculates:

Planned production time_i = max(0, S_i - PStop_i)

Run time_i = max(0, Planned production time_i - D_i)

Ideal production time_i = T_i × c_i / 60

Good count_i = max(0, T_i - R_i)

Aggregate values are the sums across all seven rows. Using aggregate planned production P, run time Run, ideal production time Ideal, total count Total, and good count Good:

Availability = Run / P

Performance_uncapped = Ideal / Run

Performance = min(1, Performance_uncapped)

Quality = Good / Total

OEE = Availability × Performance × Quality

The workbook expresses the aggregate losses as:

• downtime loss: P - Run;
• speed loss: max(0, Run - Ideal);
• quality loss: Ideal × (Total - Good) / Total;
• fully productive time: P - downtime loss - speed loss - quality loss.

TEEP uses the fixed full-week basis stored in the workbook:

TEEP = fully productive time / 10,080 minutes

Calendar utilisation = P / 10,080 minutes

The benchmark gap is 0.85 - OEE. Estimated units lost to downtime and speed use the aggregate actual production rate (Total / Run) multiplied by the corresponding loss minutes.

Calculation sequence

1. Validate each row's stop, downtime, and reject relationships.
2. Convert each row to planned time, run time, ideal production time, and good count.
3. Sum those quantities before calculating the aggregate factors. This produces weighted aggregate results rather than a simple average of daily percentages.
4. Cap performance at 100% for OEE while preserving the uncapped value as a diagnostic output.
5. Reconcile downtime, speed, quality, and fully productive minutes to planned production time.
6. Calculate OEE, TEEP, calendar utilisation, benchmark gap, and lost-unit estimates.
7. Evaluate Model_Status in the precedence below.

Outputs and interpretation

Overall_Equipment_Effectiveness is the primary product of availability, capped performance, and quality. A low factor pulls down the entire product. Performance_Uncapped is retained so data that imply performance above 100% are visible rather than silently hidden. TEEP has a different denominator from OEE and is meaningful only against the workbook's fixed seven-day, 168-hour calendar basis.

Validation and status logic

An impossible row takes precedence over aggregate zero checks. The performance warning takes precedence over the low-OEE warning.

Assumptions and limitations

• Planned and unplanned stop classifications, counts, rejects, and ideal cycle times must be supplied consistently; the workbook cannot verify their source.
• Performance above 100% usually indicates an incorrect ideal cycle or count basis. The cap prevents that value from inflating OEE but does not correct the input.
• Aggregation is weighted through summed time and count quantities, not an unweighted average of the daily chart values.
• TEEP and calendar utilisation always use 10,080 minutes. If the grid represents less than a full week, use OEE and the loss breakdown rather than interpreting TEEP as a period-normalized figure.
• Multiple products, changing ideal rates, planned shutdown policy, rework, micro-stops, and changeovers must be represented deliberately in the supplied rows; the model does not create a product-mix standard.
• The 85% world-class figure is a comparison constant, not a universal operational target.

Restrictions and non-computing states

The grid has seven fixed data rows and cannot be extended on this page. Its numeric columns reject negative entries; shift minutes are additionally constrained to 0 through 1,440. The workbook rejects a row when planned stops exceed shift minutes, unplanned downtime exceeds the remaining planned-production time, or rejects exceed total count. It also refuses an aggregate with zero planned-production time or zero total count. Blank and zero rows may remain in the grid and contribute zero to the sums.

Errors and warnings

Grid shape or cell-bound violations can be rejected by the page before the calculation runs. Workbook NOT VALID indicates internally impossible production data or an empty aggregate basis. Workbook CHECK preserves the calculated metrics while flagging a cycle-time inconsistency or very low OEE. A connection failure is not an equipment-performance finding.

The workbook states its own method rather than citing sources for it. Overall Equipment Effectiveness is a widely used industry measure, and the sources below describe the definition the workbook implements.

• Nakajima, Seiichi. Introduction to TPM: Total Productive Maintenance. Productivity Press, 1988. (the origin of Overall Equipment Effectiveness and the six big losses)
• Wikipedia. Overall equipment effectiveness. https://en.wikipedia.org/wiki/Overall_equipment_effectiveness
• Wikipedia. Total productive maintenance. https://en.wikipedia.org/wiki/Total_productive_maintenance

The 85 percent world class benchmark used on this page is a commonly quoted figure for discrete manufacturing rather than a published standard, and the workbook treats it as an editable constant.

Additional source notes migrated from Methodology

The model uses the standard OEE relationship Availability × Performance × Quality and the common TEEP calendar-time extension. The delivered reviewer packet cites OEE.com's calculation guide and its canonical single-shift example for independent arithmetic comparison.