Inventory planning
Safety Time (Safety Lead Time)
By the Supply Chain Manager team · Updated October 16, 2026
Safety time is a buffer expressed in days rather than units: you plan to receive stock a set number of days before it is actually needed.
Instead of holding a fixed quantity of safety stock, you add days of cover. The buffer then grows and shrinks with demand automatically: 4 days of safety time is 40 units for a SKU selling 10 a day and 400 for one selling 100.
It is a simpler alternative to the statistical safety stock formula and works well when you lack enough history to measure demand variability reliably.
How to calculate safety time
Safety Stock = Average Daily Demand × Safety Time (days)
Safety time example
Illustrative numbers: a supplier with an 8-day lead time and a policy of half the lead time as safety time gives 4 days. At 21 units a day, safety stock = 84 units.
Why safety time matters for distributors
Days are easier for a purchasing team to reason about than units, and the rule scales across thousands of SKUs without per-item tuning.
Common safety time mistakes
- Using the same number of safety days for steady and erratic SKUs.
- Never revisiting the rule when a supplier's reliability changes.
Safety time in Supply Chain Manager
Supply Chain Manager sets safety stock as average daily demand multiplied by half the supplier's lead time.
Open the live demoExamples on this page use made-up round numbers to show the calculation. They are not benchmarks or results from real businesses.