Close up of metal PO boxes

PO Box Cost: The Complete Guide

Determining PO box rental rates can be a bit confusing at first because the pricing varies depending on location, box size, and rental term. Luckily, once you know what to look for it’s easy to determine your PO box cost.

PO Box Cost Overview

The cost of a PO box can vary greatly depending on your location. For example, renting an extra small box for three months can be as little as $10 in some areas and as much as $67 in other areas.

You can get a rough idea of prices from the data below, which shows the average prices for PO boxes in all ZIP codes.

Average PO Box Prices

Size 1 • Extra Small

3 Months: $24 ($8/month)

Size 2 • Small

3 Months: $33 ($11/month)

Size 3 • Medium

3 Months: $57 ($19/month)

Size 4 • Large

3 Months: $96 ($32/month)

Size 5 • Extra Large

3 Months: $156 ($52/month)

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PO Box Billing & Discounts

PO boxes are billed in 3-month increments by default. Automatic billing is required for the 3-month payment option.

Paying for a 6-month period results in a 10% to 15% discount depending on the box size and your location.

The 12-month period does not receive an additional discount and is exactly twice the price of the 6-month period. However, the Post Office occasionally runs promotions offering a free month when sign up for a 12-month rental.

Finding the PO Box Cost for Your Location

The best way to calculate your actual PO box cost is to use the official USPS rate finder.

Visit the USPS.com PO Boxes Online page and click the blue “Reserve New PO Box” button:

PO box cost USPS.com rate finder screenshot

From here, you can enter your address or ZIP code to see PO box pricing and availability in your area.

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PO Box Sizes

PO boxes come in five standardized sizes. This is just a brief overview; we cover this topic in more detail in our article on PO box sizes.

Size 1: Extra Small

Dimensions: 3 x 5.5 x 14.75
Capacity: 10-15 standard envelopes or 2 magazines

Size 2: Small

Dimensions: 5 x 5.5 x 14.75
Capacity: 10-15 letters or 5 magazines

Size 3: Medium

Dimensions: 11 x 5.5 x 14.75
Capacity: Large envelopes and magazines stacked flat

Size 4: Large

Dimensions: 11 x 11 x 14.75
Capacity: 2 shoeboxes with room for 10-15 letters

Size 5: X-Large

Dimensions: 22.5 x 12 x 14.75
Capacity: Multiple packages, letters, and magazines

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Availability of Larger Sizes

Many post offices do not offer the large or extra large sizes (sizes 4 and 5).

When using the PO Boxes Online rate tool, you’ll can search search all post offices within 50 mile radius. Depending on your location, you may be able to find an alternate post office that offers the larger sizes.

If you can’t find a large PO box in your area, you may want to consider a UPS mailbox. Click here to read our article on UPS mailboxes.

Deposits & Fees

You are required to pay a $3.00 deposit for your first two keys. Additional keys require a $6.00 deposit per key.

The fee for having the lock replaced (lost key) or for a late payment is $22.00.