Injection Molding Cycle Time Calculator: Calculate Cycle Time, Parts per Hour & Parts per Shift

Injection molding cycle time is one of the most critical parameters in plastic manufacturing. It directly influences production capacity, part cost, machine utilization, and delivery timelines. Even a few seconds of improvement in cycle time can lead to significant cost savings in high-volume production.

In practice, however, cycle time estimation is not always straightforward. During product design, RFQs, and early feasibility stages, exact values such as cooling time or mold movement time are rarely available.

This guide is designed to solve that problem.

In this blog, you can:

• Estimate injection molding cycle time even without exact process data

• Calculate parts per hour and parts per shift for production planning

• Understand which factors influence cycle time the most

• Use two calculators designed for different stages of the product lifecycle

  
  

The continuous injection molding cycle. Successful estimation requires understanding the timing of each individual stage.

Who This Guide Is For

This guide is intended for:

• Product designers and design engineers

• RFQ and sourcing teams

• Manufacturing and process engineers

• Startups and OEMs planning injection-molded components

Depending on how much information you already have, you can choose the calculator that best fits your situation.

The exponential relationship between wall thickness and cooling time. Note that doubling thickness results in much more than double the cooling time.

How to Estimate Injection Molding Cycle Time When Exact Data Is Not Available

In early-stage projects, engineers often do not have access to:

• Final cooling time

• Optimized holding time

• Mold open and close duration

• Confirmed ejection method

  
  

Despite this, production planning and cost estimation still need to happen.

Instead of relying on optimistic guesses, this guide allows you to work with industry-aligned estimation ranges that help you arrive at a realistic and decision-ready cycle time before tooling or mold trials.

If you already know individual cycle parameters, you can calculate precise production output.If you don’t, the estimation approach provided here still allows meaningful planning.

Typical Injection Molding Cycle Time Ranges Used in Early Design & RFQs

Cycle Stage	Common Industry Range
Injection (Fill) Time	1–4 seconds
Holding / Packing Time	2–6 seconds
Cooling Time	Varies significantly based on part and material
Mold Open & Close Time	3–10 seconds
Ejection Time	0.5–2 seconds

Cooling is typically the dominant contributor to injection molding cycle time and has the greatest impact on cost and output.

Injection Molding Cycle Time Calculator (When Cycle Parameters Are Known)

When Should You Use This Calculator?

Use this calculator when you:

• Have experience with similar molded parts

• Are referencing historical production data

• Have results from trials or previous molds

• Can reasonably estimate individual cycle stages

  
  

This calculator focuses on production output rather than estimation.

Integrating early-stage estimation with production planning tools ensures accurate RFQs and scheduling.

Early-Stage Injection Molding Cycle Time Estimator for Product Designers & RFQs

When Should You Use This Estimator?

Use this estimator when:

• You are in the design or quoting phase

• No mold or production trial exists yet

• You need a realistic cycle time assumption, not a precise value

  
  

This estimator uses empirical industry trends and conservative assumptions to provide practical cycle time estimates suitable for early decision-making.

Download the Injection Molding Cycle Time Estimation Guide (PDF)

A practical worksheet for designers, RFQs, and early production planning—use it to estimate cycle time before tooling or trials.

Injection Molding Cycle Time Estimation Guide.pdf

Download PDF • 56.04MB

Injection Molding Cycle Time Stages Explained

Understanding the stages of injection molding cycle time helps identify where improvements are most effective.

Injection Time in the Molding Cycle

Time required to fill the mold cavity with molten plastic.

Holding and Packing Time

Pressure is maintained to compensate for shrinkage and ensure dimensional stability.

Cooling Time in Injection Molding

The longest phase of the cycle. Cooling time is influenced by part geometry, wall thickness, material behavior, and mold cooling efficiency.

Distribution of cycle time stages. Cooling typically represents two-thirds of the entire production process.

Material selection plays a significant role here. Different injection moulding materials solidify at different rates, directly affecting total cycle time.

Mold Open, Close and Ejection Time

Mechanical movements of the mold and part removal. In large tonnage injection molding, heavier molds and longer stroke lengths naturally increase this portion of the cycle.

Average Injection Molding Cycle Time by Part Size and Application

Application Type	Typical Cycle Time
Small precision parts	10–20 seconds
General industrial components	25–45 seconds
Large or thick-walled parts	60–90 seconds

• Note: These values are indicative and depend heavily on design and process conditions.

Key Factors Affecting Injection

Molding Cycle Time

• Part wall thickness

• Material thermal behavior

• Cooling channel design

• Mold temperature control

• Part geometry and rib structure

• Machine size and tonnage

  
  

Cycle time estimation should always be considered alongside dimensional stability. Tools such as a plastic shrinkage calculator help ensure faster cycles do not compromise part quality.

Strategic mold design and optimized cooling channel placement are the most effective ways to reduce total cycle time.

How to Reduce Injection Molding Cycle Time Without Sacrificing Quality

• Improve cooling efficiency

• Optimize mold design

• Reduce unnecessary mass

• Balance mold temperatures

• Introduce automation where justified

For deeper theoretical understanding of cycle time optimization and scientific molding principles, a well-structured injection molding book can be a valuable reference.

Injection Molding Cycle Time vs Takt Time

Cycle time measures how fast a machine produces a part. Takt time defines the rate required to meet customer demand.

Both must align to achieve stable and profitable production.

FAQs

What is considered one cycle time in injection molding?

One complete sequence from mold close to the next mold close.

How long does an injection molding cycle typically take?

Anywhere from 10 to 90 seconds depending on the application.

When should injection molding cycle time be calculated?

During design, RFQs, tooling planning, and production optimization.

Can the calculator help me choose between different materials?

Absolutely. Compare cycle times for different materials with similar properties. Faster-cooling materials can significantly reduce production time and costs.

How do I determine my part's wall thickness for the calculator?

Use the thickest section of your part for conservative estimates. For parts with varying thickness, use the average wall thickness or run separate calculations for different sections.

How accurate are injection molding cycle time calculators?

Most calculators provide estimates with 85-95% accuracy when proper inputs are provided. Actual cycle times may vary based on machine conditions, material variations, and operator skill. Always validate calculator results with trial runs.