For how these pieces fit together, read How serial tracking works.
Statuses
| Status | Meaning | How a serial gets here | Where it can go next |
|---|
| In Stock | On hand at a warehouse and free to ship. | Received on a purchase order, inbound shipment, inventory increase, stock take or production run; released from quarantine; restocked from a customer return; or put back when a document is voided or deleted. | Shipped, In Transit, Returned, Scrapped, Consumed, Quarantined |
| Shipped | Left the business on a shipment to a customer, or sent to a warehouse SKU.io doesn't receive into. | Shipped on a sales order, or on a transfer to an externally managed warehouse such as an Amazon fulfillment center. | In Stock (shipment voided or deleted, or customer return restocked), Quarantined or Scrapped (customer return) |
| In Transit | On a transfer between warehouses. It's still listed under the warehouse it left until the destination receives it. | Shipped on a warehouse transfer. | In Stock at the destination (transfer received), In Stock at the source (transfer shipment deleted), Scrapped (the transfer is closed with Close with Receiving Discrepancy) |
| Quarantined | Held back from sale, for example during a recall or inspection. | Quarantined from the Serial Numbers list, or quarantined on a customer return. | In Stock (released) |
| Returned | Sent back to the vendor. | Shipped on a vendor return. | In Stock (vendor return voided or deleted) |
| Scrapped | Gone and not coming back. | A stock take found fewer units than expected, an inventory adjustment decreased stock, units were scrapped during production, a transfer was closed with a receiving discrepancy (lost in transit), or a customer return was scrapped. | In Stock (the stock take, adjustment or production run is reversed or deleted, or the transfer shipment is deleted) |
| Consumed | Used up as a component of something you built. | Used on a manufacturing order or an assembly, or a kit was taken apart. | In Stock (production reversed or assembly deleted) |
| Allocated | Reserved for an order. | Not used by any screen today. | — |
| Committed | Locked to a shipment before it ships. | Not used by any screen today. | — |
Deleting a customer return's receipt puts each of its serials back the way it was before the return, usually Shipped on its original order. Serials the return added to SKU.io are removed.
Account settings
In Settings → Inventory → Serial & Lot Tracking:
| Setting | What it does | Options |
|---|
| Enable Serial Number Tracking | Master switch for your account. No product can track serials while it's off. | On, off (default off) |
| Default Serial Generation Mode | How a newly serial-tracked product creates serials. Each product can override it. | None, Manual entry (default), Auto-generate |
| Default Serial Format | The template used to generate serials for products that auto-generate. | Any text with a sequence token ({seq} or {seq:N}), checked when you save. Default {sku}-{seq:6} |
| Outbound Serial Match Mode | What happens when someone names a serial that can't be shipped or removed. | Require exact match (default) blocks it; Log and allow mismatch lets it go ahead |
Product settings
On the product's Serial & Lot Tracking section, in the Serial Number Tracking card:
| Setting | What it does |
|---|
| Track serial numbers for this product | Turns serial tracking on for this product. It can't be turned on while the account master switch is off. |
| Generation Mode | None (manual entry at movement time), Manual (user enters, system validates uniqueness) or Auto (system generates via format). |
| Format Override (optional) | A serial format for this product only. Leave it blank to use the account's Default Serial Format. Only used when the Generation Mode is Auto. Must include a sequence token, checked when you save. |
A format is plain text with tokens that SKU.io fills in when it generates each serial. Tokens aren't case-sensitive, so {SEQ:6} and {seq:6} are the same.
| Token | Becomes | Example |
|---|
{sku} | The product's SKU | DRILL-18V |
{seq} | The next number in the product's sequence | 42 |
{seq:N} | That number, padded with zeros to N digits | {seq:6} → 000042 |
{yyyy} | The four-digit year the serial was generated | 2026 |
{yy} | The two-digit year | 26 |
{mm} | The month, two digits | 09 |
{dd} | The day, two digits | 27 |
Every format needs a sequence token ({seq} or {seq:N}). Without one, each generated serial would be the same. SKU.io checks this when you save the account's Default Serial Format or a product's Format Override, and won't save a format that has no sequence token.
The sequence continues from the number of serials the product has ever had. SKU.io skips any value that already exists, including serials whose receipt was deleted.
Messages you might see
The messages name the serial and the product SKU, shown here as SERIAL and SKU.
Receiving or adding stock
| Message | What to do |
|---|
| SKU is tracked by serial number, so its quantity must be a whole number. | Serial-tracked stock moves in whole units. Correct the quantity. |
| N serial numbers were entered for SKU, but the quantity is Q. Enter one serial per unit. | Enter exactly one serial per unit, or clear the list where blank is allowed. |
| N serial numbers were entered for SKU, but only Q units. Enter at most one serial per unit. | For an auto-generating product, remove the extra serials. SKU.io generates the rest. |
| Serial "SERIAL" for SKU is listed more than once. Enter each serial once. | Remove the repeat. |
| Serial "SERIAL" already exists for SKU. Each serial can only be received once. | Check the serial. Search for it on the Serial Numbers list to see where it is. |
Can't generate new serials for SKU from the format "FORMAT". Add a sequence token such as {SEQ:6} to the serial format. | Add {seq} or {seq:6} to the product's Format Override or the account's Default Serial Format. |
| Message | What to do |
|---|
The serial format must include {seq} or {seq:N} (for example {sku}-{seq:6}), so every generated serial is different. | Add a sequence token to the format, then save again. |
Receiving a customer return, with Require exact match
| Message | What to do |
|---|
| Serial "SERIAL" was never recorded for SKU, so it can't be received as a return. Check the serial, or switch Outbound Serial Match Mode to Log and allow mismatch. | Check for a typo. If the unit is genuinely yours but was never recorded, switch Outbound Serial Match Mode to Log and allow mismatch, and SKU.io adds the serial with the disposition you chose. |
Quarantine and release
| Message | What it means |
|---|
| N serial(s) quarantined. M skipped because they aren't in stock. | Only serials that are In Stock, Allocated or Committed can be quarantined. The rest were left as they are. |
| None of the selected serials were quarantined. Only serials that are In Stock, Allocated or Committed can be quarantined. | Nothing you selected is on hand. |
| N serial(s) released back to stock. M skipped because they aren't quarantined. | Only quarantined serials are released. |
| None of the selected serials were released. Only quarantined serials can be released. | Nothing you selected is quarantined. |
Assigning serials to a shipment
| Message | What it means |
|---|
| Serials assigned. | Every unit on the line now has a serial, and the Serials missing chip is gone. |
| Serials assigned. N units still have no serial in stock. | The warehouse ran out of serials. Record the missing serials, then click Assign serials again. |
Shipping, with Require exact match
| Message | What to do |
|---|
| Serial "SERIAL" was not found for SKU, so it can't be shipped. | Check for a typo, or receive the unit first. |
| Serial "SERIAL" for SKU can't be shipped because it is STATUS. | The unit isn't available. Pick another serial, or release it from quarantine first. |
| Serial "SERIAL" for SKU is in a different warehouse, so it can't be shipped from this one. | Ship from the warehouse that holds it, or pick a serial from this warehouse. |
| Serial "SERIAL" was not found in stock for SKU, so it can't be shipped. | Same as above. This version appears when the shipment is recorded. |
| Serial "SERIAL" for SKU is not in stock (status: STATUS), so it can't be shipped. | Same as above. |
Removing stock: vendor returns, stock takes, manufacturing, transfers
| Message | What to do |
|---|
| Serial "SERIAL" for SKU is not in stock at this warehouse (status: STATUS). | Pick a serial that's In Stock at this warehouse, or leave the list blank to use the oldest. |
| Serial "SERIAL" was not found in stock for SKU. | Check for a typo. |
| Serial "SERIAL" for SKU is not in transit on this shipment, so it can't be received here. | When receiving a transfer, name only serials that left on this shipment, or leave the list blank. |
Substituting a product
| Message | What it means |
|---|
| Heads up: SKU is serialised and SKU is not. Pick and pack steps will differ. | You paired a serial-tracked product with one that isn't. The substitution still works, but only the serial-tracked product asks for serials. |
| Tooltip | Where |
|---|
| Enter one serial number per received unit on every serialized line before receiving. | Purchase order and inbound shipment Receive |
| None of the selected serials are in stock. Only In Stock, Allocated or Committed serials can be quarantined. | Quarantine in the Serial Numbers list, with several serials selected |
| Only serials in stock can be quarantined — this one isn't on hand. | The Quarantine icon on a serial's row |
| None of the selected serials are quarantined. | Release in the Serial Numbers list, with several serials selected |
| Enter one serial for each unit on the line, or leave the serials blank to send the oldest in stock. | Transfer and vendor return Ship |
| Enter one serial for each unit on the line, or leave the serials blank to ship the oldest in stock. | Fulfillment order Submit |
| Enter one serial for each component unit used, or leave the serials blank to use the oldest in stock. | Manufacturing order Record Production (components) |
| Enter one serial for each unit produced (Auto-generation products may leave it blank). | Manufacturing order Record Production (outputs) |
| Enter one serial per unit of variance on serialized items (found units need their serials unless the product generates them; a shortfall may be left blank): SKUs. | Stock take Finalize |
Where serials print
| Document | What it shows |
|---|
| Pick list | For each serialized line, the oldest serials in stock at the warehouse, as a suggestion for the picker, each with a checkbox to tick as you pick. Printed only while Enable Serial Number Tracking is on. |
| Packing slip | The serials that shipped on each line, each with a checkbox. A serialized line with no serials yet prints — serials pending —. |
| Invoices and sales order PDFs | No serials. |
Who can see serials
Anyone who can view inventory can open Inventory → Serial Numbers, look up a serial's history, and quarantine or release serials. There's no separate serial permission.
What serial tracking doesn't do
- No serial import or export. Serials can't be loaded from or exported to a spreadsheet. Record them on each receipt.
- No adding serials to existing stock. Turning tracking on doesn't create serials for units you already hold, and no screen attaches serials to them without changing the quantity.
- No recall screen. There's no screen that lists every customer who received a serial or batch. Look serials up one at a time on the Serial Numbers list.
- No warranty tracking. Warranty start dates and registration numbers aren't recorded.
- Amazon-fulfilled orders don't record serials, because Amazon picks the units.
- No shipping ahead of stock. A serial-tracked product never ships into negative stock or inventory debt, whatever your negative-inventory settings say, because a serial can't ship before it exists. See When a shipment is refused.
- Editing a received quantity doesn't change serials. Changing the quantity on an inbound shipment's receipt line doesn't add or remove serials. To correct serials, delete the receipt and receive it again.
- Amazon removal-order receipts (stock coming back from Amazon to your warehouse) don't record serials.