How do you calculate days of inventory coverage?

Divide usable inventory (including the safety-factor adjustment) by daily usage. With 1,200 pieces on hand, 85 pieces/day usage and a 1.1 safety factor, this returns about 12.8 protected days of supply versus 14.1 unprotected days.

What is the difference between protected and unprotected days?

Unprotected days (14.1 here) is raw inventory divided by usage. Protected days (12.8) applies the 1.1 safety factor so you hold a buffer; the gap between them is the cushion you have reserved against demand or supply variability.

What is a good number of days of coverage for nonwoven raw materials?

It should comfortably exceed your replenishment lead time plus a buffer. If polymer lead time is 10 days, 12.8 protected days is adequate but thin; for volatile specialty fibers many plants target lead time plus 30-50%.

How does the safety factor change coverage?

A factor above 1.0 reserves part of your stock as buffer, lowering reported protected days below the unprotected figure. The 1.1 factor here pulls 14.1 unprotected days down to 12.8 protected days, reflecting roughly a 10% reserve.

When should I trigger a replenishment order?

When protected days of supply approach your supplier lead time. If lead time is 12 days and you are at 12.8 protected days, you are essentially at the reorder point and should place or expedite the PO now.

Does this account for in-transit or on-order stock?

No. It looks only at on-hand inventory. If you have material already in transit, add it conceptually or run a separate coverage for net available stock to avoid over-ordering.

Nonwoven Materials & Technical Textiles calculator

Inventory Coverage Calculator

Inventory Coverage tells a nonwoven or technical-textile operation how many days of demand its current roll or fiber stock will cover before a replenishment must land. It compares those protected days against the lead time to bring in more polymer, staple fiber, or finished rolls, so planners can see at a glance whether a line is at risk of starving. Supply planners and warehouse leads use it to time purchase orders, size safety stock, and decide when an expedite is justified. In a business where lead times on polypropylene resin or specialty fiber can stretch for weeks, knowing your true days of cover is the difference between a smooth run and an unplanned line stop.

What this calculator does

Estimate inventory coverage for nonwoven materials and technical textiles using production-ready inputs so teams can plan replenishment and safety stock using actual usage and lead time.
Use it when inventory coverage in nonwoven materials and technical textiles is being sized for a buffer or safety stock review.
It converts on-hand inventory and daily usage into protected days of supply and compares that against the replenishment lead time.

Formula used

Inventory coverage cycle stock = inventory coverage daily usage × inventory coverage lead time
Required inventory coverage inventory = cycle stock + inventory coverage safety stock

Inputs explained

Roll stock on hand at the slitter:
Replenishment lead time for fiber/polymer:
Safety-stock multiplier:

How to use the result

Use it when scheduling raw-material POs, reviewing safety stock, or judging whether current stock can ride out a supplier delay.
It assumes steady daily usage; a demand spike or a quality hold on incoming material can erode the protected days faster than the figure implies.

Current U.S. benchmarks

Industrial electricity averages 8.66 cents per kWh across the U.S. (EIA, Apr 2026), up 5.5% from a year earlier. Energy-intensive steps carry this directly into unit cost.

Common questions

How do you calculate days of inventory coverage? Divide usable inventory (including the safety-factor adjustment) by daily usage. With 1,200 pieces on hand, 85 pieces/day usage and a 1.1 safety factor, this returns about 12.8 protected days of supply versus 14.1 unprotected days.
What is the difference between protected and unprotected days? Unprotected days (14.1 here) is raw inventory divided by usage. Protected days (12.8) applies the 1.1 safety factor so you hold a buffer; the gap between them is the cushion you have reserved against demand or supply variability.
What is a good number of days of coverage for nonwoven raw materials? It should comfortably exceed your replenishment lead time plus a buffer. If polymer lead time is 10 days, 12.8 protected days is adequate but thin; for volatile specialty fibers many plants target lead time plus 30-50%.
How does the safety factor change coverage? A factor above 1.0 reserves part of your stock as buffer, lowering reported protected days below the unprotected figure. The 1.1 factor here pulls 14.1 unprotected days down to 12.8 protected days, reflecting roughly a 10% reserve.
When should I trigger a replenishment order? When protected days of supply approach your supplier lead time. If lead time is 12 days and you are at 12.8 protected days, you are essentially at the reorder point and should place or expedite the PO now.

Last reviewed 2026-05-12.