Lead Time Calculator

Breaking down lead time

Lead time is the total elapsed time from when an order is placed to when inventory is ready for use. It is a critical input for reorder point calculations, safety stock planning, and service level commitments. A lead time estimate should include every step in the process: order processing, supplier production or pick/pack, transportation, customs or inspection, and receiving or put-away. Each step adds time that your business must cover with inventory or service buffers.

The calculator separates core steps from an optional buffer. Core steps represent the expected or average duration of each stage, while the buffer accounts for variability. Buffers can be set based on historical volatility, supplier performance, or risk tolerance. If your supply chain is highly variable, the buffer may need to be larger to protect service levels. If you have robust reliability data, you can set a smaller buffer and reduce total lead time in planning models.

Lead time is not always constant. It can change with seasonality, congestion, or supplier capacity. For that reason, many organizations track lead time as a distribution rather than a single number. This calculator provides a simple, transparent total that you can use for planning or scenario analysis. It can also help you compare different sourcing strategies, such as domestic vs overseas production, by mapping each step and the resulting total.

Because lead time is expressed in days and weeks, it is easy to compare with demand cycles and inventory turnover. If lead time approaches or exceeds your coverage days, you may need to adjust safety stock or order quantities. This calculator keeps the math local to your browser for privacy.

Many organizations track both planned lead time and actual lead time. The gap between them highlights process constraints and opportunities for improvement. By breaking the total into components, you can target the biggest drivers first, such as supplier changeovers, port congestion, or internal receiving bottlenecks. This granular view makes lead time reduction efforts more focused and measurable.

Formula

Total lead time: Order Processing + Production + Transit + Customs + Receiving + Buffer

Weeks: Total Lead Time / 7

Example calculation

If order processing is 2 days, production is 7 days, transit is 5 days, customs is 1 day, receiving is 1 day, and buffer is 1 day, total lead time is 2 + 7 + 5 + 1 + 1 + 1 = 17 days. That is 17 / 7 = 2.43 weeks.

FAQs

What is lead time?

Lead time is the total time from order placement to inventory being available for use or sale.

Which steps should be included?

Include order processing, supplier production, transit, customs or inspection, and receiving time.

Why add a buffer?

Buffers account for variability so plans stay reliable when conditions change.

Is this calculator private?

Yes. All calculations run locally in your browser.

How it works

This calculator sums each lead time component and converts total days to weeks. All computation is client-side for privacy.

Disclaimer

Lead time estimates depend on reliable process data. Review actual supplier and carrier performance for production planning.