# How to Ship with Poly Mailers on Palmstreet

### **What is a Poly Mailer?**

A poly mailer is a lightweight, waterproof plastic shipping bag made from polyethylene. It’s flexible, tear-resistant, and seals with a self-adhesive strip, making it a popular packaging choice for soft, non-fragile items like clothing and accessories.

Because poly mailers weigh almost nothing and take up very little space, they can significantly reduce your shipping costs compared to cardboard boxes.

### **When Should You Use One?**

<mark style="color:$success;">**✓**</mark>**&#x20;Good for**

* Clothing (T-shirts, dresses, leggings)
* Accessories (scarves, belts, hats)
* Cosmetics and small beauty items
* Books and magazines
* Plush toys and soft goods

<mark style="color:$danger;">**×**</mark>**&#x20;Not suitable for**

* Glassware or ceramics
* Electronics
* Anything fragile or rigid
* Items that need to hold their shape in transit

### **Common Poly Mailer sizes**

Choose a mailer that fits your item snugly when flat. Use the empty mailer’s dimensions, not the packed size, when filling in length and width.

| <h4><strong>Size</strong></h4> | <h4><strong>Length × Width</strong></h4> | <h4><strong>Best for</strong></h4>    |
| ------------------------------ | ---------------------------------------- | ------------------------------------- |
| **Small**                      | 6" × 9"                                  | Jewelry, socks, small accessories     |
| **Medium**                     | 10" × 13"                                | T-shirts, shorts, lightweight tops    |
| **Medium Large**               | 12" × 15.5"                              | Folded shirts, light pants            |
| **Large**                      | 14.5" × 19"                              | Sweatshirts, jeans, multi-item orders |
| **XL**                         | 19" × 24"                                | Jackets, bulky apparel                |

### **How to Get Poly Mailer Rates from USPS When Buying a Label**

Palmstreet currently supports poly mailer pricing through the **Custom Rate** flow. The key is to enter your mailer’s flat dimensions with a height of **0.25 inches:** this small height signals to carriers that the package is a flat soft-pack, which qualifies for lower **USPS rates**.

Note that **UPS and FedEx** do not offer special soft-pack pricing; for those carriers, standard dimensional weight pricing applies.

{% hint style="info" %}
💡 **Why 0.25"?**

USPS calculates rates for flat soft-pack mailers using only the length and width — thickness is effectively ignored. Setting height to 0.25" tells the system this is a flat mailer, not a box, so you get the correct lower rate automatically when you select a USPS service.
{% endhint %}

<figure><img src="/files/9WBJ9Wodkr7gT6mPfkUr" alt=""><figcaption></figcaption></figure>

1. **Open the shipment and click Buy Label**

From your order dashboard, open the order and click *Buy Label* to start the shipping flow.

1. **Select the "Custom Rate" tab**

At the top of the Package detail section, click *Custom Rate*. This lets you manually enter your package dimensions.

1. **Enter your mailer dimensions**

Fill in the length and width of your empty mailer (lying flat). Set**Height to 0.25"**. Then enter the total package weight (item + mailer bag).

1. **Select a USPS service and purchase**

Choose your preferred USPS service (e.g. USPS Ground Advantage or Priority Mail). Because of the flat dimensions you entered, the rate returned will already reflect poly mailer pricing — no extra steps needed.

{% hint style="info" %}
&#x20;📌 **Save time with Shipping Presets**

If you regularly ship with the same mailer size, save these settings as a *Shipping Preset* under Store Settings.

Read [**How to add shipping presets in the Seller Hub**](https://help.palmstreet.app/seller/palmstreet-shipping-guide/shipping-tools/seller-hub-tools/how-to-add-shipping-presets-in-the-seller-hub)
{% endhint %}

### **Tips to Avoid Extra Charges**

#### **Use flat, non-gusseted mailers**

A *gusseted* or *expandable* mailer has pleated sides that let it expand. Carriers can reclassify these as boxes and apply standard dimensional weight pricing. Always use flat poly mailers to keep costs low.

#### **Don’t overstuff the mailer**

If a mailer bulges significantly when packed, carrier scanners will measure the widest point rather than the flat dimensions. This can increase your DIM weight or trigger additional handling surcharges, even if your empty mailer was within limits.

#### **Watch size limits for UPS and FedEx**

UPS and FedEx do not have special soft-pack pricing. They bill based on actual vs. DIM weight (whichever is greater), and apply an **Additional Handling surcharge** to soft-sided packages that exceed these dimensions:

{% hint style="info" %}
📌 **Recommendation**

For poly mailer shipments, USPS Ground Advantage or USPS Priority Mail will give you the best rates. Use UPS or FedEx only if speed or coverage requires it.
{% endhint %}

### **FAQ**

**We answer common questions about poly mailers below:**

#### **Why do I need to set height to 0.25"?**

USPS uses a flat soft-pack formula that ignores height for poly mailer pricing. By setting height to 0.25", you signal to the system that this is a flat mailer rather than a box, which ensures you receive the correct lower rate. If you leave height at 0 or enter a larger number, you may be quoted standard box rates instead.

#### **What weight should I enter?**

Enter the total weight of the packed, sealed package: item plus the mailer bag itself. Poly mailer bags typically weigh 0.3–0.8 oz depending on size, so you can round up to the nearest ounce to be safe.

#### **Does this work for UPS and FedEx too?**

You can use the same dimension setup for UPS and FedEx, but there is no special soft-pack pricing for those carriers. The main benefit with UPS/FedEx is that a lightweight mailer reduces your actual weight charge.

#### **Can I save my poly mailer settings as a preset?**

Yes. Go to **Settings → Shipping Presets** and create a preset using the dimensions above (e.g. 10" × 13" × 0.25"). Once saved, apply it in one tap when buying any label.


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