# Hardware step 2: units, boxes and lengths

> Sell screws by the piece or box, nails by the pound or box, and rope by the foot or spool with base units, sub-units and decimal quantities.

Source: https://docs.smartposhub.com/business-types/hardware/step-2-units-boxes-and-lengths/  
Last updated: 2026-10-30  
Product: SmartPOS Hub (https://smartposhub.com)

Hardware is sold in many sizes: one screw or a box of 100, a pound of nails or a 5 lb box, a foot of rope or a 100 ft spool, a bag of concrete or a pallet. In SmartPOS Hub each product has one **base unit** that stock is counted in, plus optional **sub-units** that are multiples of it. This page shows how to set them up and how cashiers use them.

## Before you start

- **Enable Sub Units** is ticked in **Settings › Business Settings › Product** ([step 1](https://docs.smartposhub.com/business-types/hardware/step-1-stores-yard-and-settings/)).
- Decide the base unit for each product family: the smallest amount you ever sell (piece, pound, foot, board, bag).

## Typical hardware units

| Base unit | Sub-units | Allow decimal |
|---|---|---|
| Pieces | Box (10), Box (25), Box (50), Box (100), Case (12) | No |
| Lb | Box (5 lb) | Yes, if you weigh loose nails |
| Ft or Metre | Spool (100 ft), Coil (250 ft) | Yes, for cut lengths |
| Board | Bundle (10), Unit (208) | No |
| Bag | Pallet (42 bags), Pallet (56 bags) | No |
| Service | none | No |

## Create the base units and sub-units

1. Open **Products › Units**. Click **Import prebuilt** to add common units in one go, or click **Add**.
2. For a base unit, enter **Name** and **Short name** (for example Pieces / Pc(s)) and set **Allow decimal**.
3. For a sub-unit, enter the name (for example Box (100)), tick **Add as multiple of other unit**, type **100** in **times base unit** and pick the base unit (Pieces).
4. Save. The list shows the sub-unit with its size, such as Box (100) (100Pc(s)).

![Units list with Bag, Board, Box (10), Box (100), Box (25), Box (5 lb), Bundle (10), Coil (250 ft), Ft, Lb, pallet units, Pieces, Service and Spool (100 ft)](https://docs.smartposhub.com/_astro/units-list.DB8hFjAG.png) (web app page: `/units`)
*Products › Units in a hardware store: base units such as Ft, Lb, Board and Bag, and sub-units with their size in brackets.*

## Attach units to a product

1. Open **Products › Add Product** (or edit an existing one).
2. In **Unit**, choose the base unit, for example Pieces.
3. In **Related Sub Units**, pick the packs this product is sold or bought in, for example Box (100). Leave it empty to allow every sub-unit of that base unit.
4. Enter prices for **one base unit** on the **Pricing** tab. Save.

![Add new product form, Basic info tab, with Unit and Related Sub Units fields highlighted](https://docs.smartposhub.com/_astro/product-form-sub-units.lhomg0zf.png) (web app page: `/products/create`)
*Unit is the base unit stock is counted in. Related Sub Units are the packs offered at the till and on purchases.*

## Sell by the box, the piece or the foot

In the POS, each line with sub-units gets a unit dropdown under the quantity. The cashier picks **Box (100)** or **Pieces**; the price and the stock deduction follow the multiplier.

![POS cart with 1-1/4 in galvanized roofing nails as Box (5 lb) for 15.95 and #10 x 3 in exterior deck screws as Box (100) for 24.00](https://docs.smartposhub.com/_astro/pos-sell-by-box.BuLNRZpW.png) (web app page: `/pos/create`)
*One box of 5 lb of nails and one box of 100 screws. The stock goes down by 5 lb and 100 pieces.*

For cut lengths, type a decimal quantity such as **12.5** on a unit with **Allow decimal** on. The tiles show stock in the base unit, for example "145.00 ft in stock".

## Tips and mistakes to avoid

- **Price per base unit.** The box price is always base price × size. If boxes should be cheaper, add a [discount](https://docs.smartposhub.com/catalog/prices-and-discounts/) or sell the box as a variation with its own price ([variable products](https://docs.smartposhub.com/catalog/variable-products/)).
- **Box-only items.** For fasteners you never split, choose only the box in **Related Sub Units**. Staff then cannot sell a single screw by mistake.
- **Receive in packs too.** The purchase screen also has the unit dropdown, so a pallet of 56 bags adds 56 bags of stock.
- Print shelf labels per unit with **Products › Print Labels** ([barcodes and labels](https://docs.smartposhub.com/catalog/barcodes-and-labels/)).

Next: [step 3: load a large catalog](https://docs.smartposhub.com/business-types/hardware/step-3-load-a-large-catalog/).

  - [Categories, brands and units](https://docs.smartposhub.com/catalog/categories-brands-units/)
  - [Add products](https://docs.smartposhub.com/catalog/add-products/)
  - [Variable products](https://docs.smartposhub.com/catalog/variable-products/)

## Frequently asked questions

### What is a sub-unit?

A bigger pack of a base unit, such as Box (100) = 100 Pieces or Spool (100 ft) = 100 Ft. You create it in Products › Units with Add as multiple of other unit, and stock is always kept in the base unit.

### How is the box price worked out?

From the base price times the multiplier. If one screw sells for 0.24, Box (100) sells for 24.00. To give a cheaper box price, use a discount or sell the box as its own variation with its own price.

### Can I stop a product from being sold by the piece?

Yes. In Related Sub Units on the product, pick only the box. The POS then sells it only in boxes, and the stock still shows in pieces.

### How do I sell 2.5 metres of chain?

Give the length unit Allow decimal = Yes. The cashier can then type 2.5 as the quantity. Units with Allow decimal = No only accept whole numbers.

### Can I buy in pallets and sell in bags?

Yes. Create Pallet (56 bags) as a sub-unit of Bag. On the purchase line choose Pallet (56 bags); stock goes up by 56 bags for each pallet.

### Can I change a product's base unit later?

Avoid it once the product has stock or sales, because past quantities are stored in the old unit. Set the base unit right before you import opening stock.