Quality & Process Control

Yield Calculator

Calculate production yield, defect rates, and rolled throughput yield (RTY) for single or multi‑stage processes. Identify losses and improve overall equipment effectiveness (OEE).

Process Yield Overview

Input100%ProcessYield: 85%Good85%Scrap / Rework15%

Input Data

units

Total input quantity

units

Units meeting specifications

units

Units rejected or scrapped

* Enter either Good or Defective; the other will be calculated automatically.

Pro Tip

Rolled Throughput Yield (RTY) is more meaningful than average yield because it reveals the cumulative effect of defects. Always aim to improve the step with the lowest yield first.

Simple Yield Results

Yield

85.00%

Defect Rate

15.00%

Good Units

850

Defective

150

0%85.00% Yield100%

Governing Formula

Yield = (Good / Total) × 100
Yield

%

Engineering Code

Python
def yield_simple(total_units, good_units):
    if total_units <= 0:
        raise ValueError('Total must be positive')
    yield_pct = (good_units / total_units) * 100
    defect_pct = 100 - yield_pct
    return {'yield': yield_pct, 'defect': defect_pct, 'good': good_units, 'total': total_units}

res = yield_simple(1000, 850)
print(f"Yield: {res['yield']:.2f}%")
print(f"Defect Rate: {res['defect']:.2f}%")

Technical Explanation: Yield, Defect Rate, and Rolled Throughput Yield

Yield is a critical quality metric that measures the proportion of products that meet specifications out of total produced. It can be calculated at a single step or across multiple process steps.

Key Metrics

  • Yield (%) = (Good Units / Total Units) × 100
  • Defect Rate (%) = (Defective Units / Total Units) × 100
  • Rolled Throughput Yield (RTY) = Product of yields at each step (for multi‑stage processes). RTY represents the probability that a unit passes all steps without rework.
  • First Pass Yield (FPY) = Yield without rework – the proportion that passes on the first attempt.

How to Use the Calculator

  1. Select mode: Choose Simple (single process) or Multi‑Stage.
  2. For Simple mode: Enter total units and good units (or defect count). The calculator shows yield, defect rate, and a visual gauge.
  3. For Multi‑Stage mode: Add each process step with its good/total counts. The calculator computes individual yields and the overall RTY, plus identifies the bottleneck step (lowest yield).
  4. Results include a summary table, a bar chart (conceptual), and Python code.

Real-World Engineering Cases

Electronics Assembly: Improving RTY

A PCB assembly line had three steps: SMT placement (98% yield), reflow soldering (95%), and inspection (92%). The rolled throughput yield was 0.98×0.95×0.92 = 85.6%. By improving inspection with automated optical inspection (AOI), they raised the last step to 97%, increasing RTY to 90.3% and saving $200k annually in rework costs.

Engineering Lesson

RTY reveals the true cumulative effect of defects. Improving the worst‑performing step gives the biggest gain.

Food Processing: Reducing Scrap

A dairy plant had a 92% yield in pasteurization. By analyzing the 8% loss, they found 5% was due to temperature fluctuations. After installing better controls, yield rose to 96%, reducing raw material waste and increasing capacity.

Engineering Lesson

Even small yield improvements can have significant financial impact, especially in high‑volume production.

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Frequently Asked Questions

What is the difference between Yield and First Pass Yield (FPY)?

Yield typically includes units that were reworked and then passed. FPY counts only units that passed on the first attempt without any rework. FPY is a stricter measure of process quality.

Why is Rolled Throughput Yield (RTY) important?

RTY gives the overall probability that a product will pass all process steps without defect. It highlights the cumulative effect of defects and helps prioritise improvement efforts on the weakest step.

Can I use this for non‑manufacturing processes?

Absolutely. Yield can be adapted to any process where inputs are transformed into outputs with possible defects, such as software testing (pass/fail), customer support (resolved cases), or even document processing.