📦 US Shipping Calculator

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Dimensional weight (DIM) calculator — formula shown on this page: (L × W × H) ÷ 139 (inches → pounds).

Length (inches)

Width (inches)

Height (inches)

Rebuilt 2026-10-09.

How the Zone System Works

USPS, UPS and FedEx divide the US into shipping zones (1 - 8) based on the distance between origin and destination ZIP codes. The further the package travels, the higher the zone number and the more expensive the shipping cost.

Zone	Distance (miles)	Example Route
1	0 - 50	Local / same city
2	51 - 150	Los Angeles → San Diego
3	151 - 300	Los Angeles → Phoenix
4	301 - 600	Los Angeles → Denver
5	601 - 1,000	Los Angeles → Chicago
6	1,001 - 1,400	Los Angeles → Dallas
7	1,401 - 1,800	Los Angeles → New York
8	1,801+	Los Angeles → Boston

USPS Flat Rate Box Prices (2025)

Flat Rate boxes ship any weight (up to 70 lbs) to any zone in the US at one fixed price. Best for heavy items going long distances.

Box Type	Dimensions	Ground / Retail	2-Day^®	Priority Mail Express
Small Flat Rate Box	8⅝" × 5⅜" × 1¾"	$10.40	$10.40	—
Medium Flat Rate Box (Top-Load)	11¼" × 8¾" × 6"	$17.60	$17.60	—
Medium Flat Rate Box (Side-Load)	13⅝" × 11⅞" × 3⅜"	$17.60	$17.60	—
Large Flat Rate Box	12¼" × 12¼" × 6"	$24.40	$24.40	—
Priority Mail Express Flat Rate Box	12½" × 9½" × 2"	—	—	$30.95
Priority Mail Express Flat Rate Box (Big)	15⅝" × 14⅛" × 3"	—	—	$46.95

Pro Tip

If your package weighs more than 10 lbs and is traveling Zone 5+, a Flat Rate box is almost always cheaper than regular Priority Mail by weight.

USPS Regional Rate Boxes

Regional Rate boxes are priced by zone:

Box Type	Max Weight	Zone 1 - 2	Zone 3	Zone 4
Regional Rate Box A	15 lbs	$9.75	$12.50	$15.25
Regional Rate Box B	20 lbs	$12.50	$16.50	$20.75

How to Save on Shipping

📏 Use Flat Rate Boxes for Heavy Items

If your package weighs over 10 lbs, check USPS Flat Rate pricing. A 50-lb package costs the same as a 1-lb package in a Flat Rate box. Especially valuable for Zone 7 - 8 shipments.

⚖ Keep It Under Key Weight Thresholds

Shipping costs jump at certain weights. Keep packages under 1 lb, 2 lbs, 5 lbs, 10 lbs, 20 lbs, and 50 lbs to avoid crossing into the next price tier. Use a lighter box or poly mailer.

📐 Dimension Weight (DIM) Matters

All three carriers use dimensional weight (DIM) pricing. If your box is large but light, you pay for the space it takes up. DIM divisor for USPS/UPS/FedEx is typically 139 (domestic). Formula: (L × W × H) ÷ 139. Round up to next pound. Keep boxes as small as possible.

🏷 Use Your Own Packaging

For lighter items, using your own packaging with USPS Priority Mail Cubic (for packages under 0.5 cu ft) can be cheaper than Flat Rate boxes. UPS and FedEx also offer discounts for online labels.

Compare Carriers Every Time

No single carrier is cheapest for every package. Use this calculator to compare all three before printing a label. Sign up for free business accounts to get up to 89% off retail rates.

🚚 Ship Ground When Possible

Ground shipping is significantly cheaper than 2-Day or Overnight. Unless the package is urgent, always pick Ground to save 40 - 70%.

⚠ Avoid Retail Counter Rates

🗓 Zone Skipping for Frequent Shippers

If you ship many packages to the same region, consolidate and use a zone-skipping service (UPS SurePost, FedEx SmartPost) to hand off to USPS for final delivery at a lower cost.

Carrier Comparison: USPS vs UPS vs FedEx

Feature	USPS	UPS	FedEx
Best For	Small & light packages, PO boxes, rural	Heavy packages, business B2B, guaranteed	Time-definite deliveries, weekend options
Ground Speed	2 - 5 business days	1 - 5 business days	1 - 5 business days
Saturday Delivery	Included (Priority Mail)	Extra charge	Extra charge
Free Packaging	Priority Mail boxes & envelopes	Must supply own	Must supply own
Max Weight	70 lbs (most services)	150 lbs	150 lbs
Tracking Included	All services	All services	All services
Insurance Included	$100 (Priority Mail)	$100 (Ground)	$100 (Ground)
PO Box Delivery	Yes	No	No
Residential Surcharge	None	~$4.95 per pkg	~$4.95 per pkg
Discounts via 3rd Party	Pirateship, Shippo	Shippo, Easyship	ShipStation, Shippo
DIM Divisor	166 (retail) / 139 (online)	139	139

USPS Pros

Free boxes & envelopes
Lowest cost for <2 lbs
Saturday delivery included
Delivers to PO boxes
Flat Rate pricing eliminates zones

⚠ USPS Cons

70 lb weight limit
Tracking can be less detailed
No guaranteed delivery times (Ground)
Slower on long haul routes

UPS Pros

Excellent tracking technology
Reliable for heavy packages
Time-definite delivery guarantees
150 lb max weight

⚠ UPS Cons

Residential surcharge (~$5)
No free packaging
More expensive for light packages
Saturday delivery costs extra

FedEx Pros

Strong weekend delivery options
Best for time-definite freight
150 lb max weight
Good international network

⚠ FedEx Cons

Residential surcharge (~$5)
No free packaging
More expensive for light packages
Claims process can be slow