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Free USPS shipping cost calculator for sellers and shippers. Compare volume-based billing, Priority Flat Rate packaging, Ground Advantage™, Express, and Media Mail® before you print a label.
Not affiliated with the United States Postal Service®.
Last updated: April 13, 2026
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Proof of delivery / signature
Remote or DDU-style delivery (illustrative)
Odd shape / rigid items (modeled)
Estimated total postage
$17.27
1–3 business days (USPS Priority Mail®)
Billed weight
10 lb
Dim weight
6 lb
Base (zone)
$17.27
Extras
$0.00
Custom boxes use dimensional weight with divisor 166. Flat Rate pricing follows Priority-style retail bands in this model. USPS updates retail prices periodically; this tool does not add a separate fuel line.
Common retail divisor
166 in³/lb
When DIM exceeds actual weight, postage tables typically use the higher value.
Planning
ZIP-to-ZIP lanes
Longer lanes increase base postage before optional extras.
If it fits, it ships
Up to 70 lb
Great for heavy small goods when retail Flat Rate beats weight-rated Priority.
Ecommerce staple
2–5 day style
Compare against Priority when delivery speed matters.
Fast lane
Overnight / 1-day
Higher base and per-pound slope in this simplified estimator.
Checkout reality
Add-ons stack
See why the final label price differs from "base postage."
12 × 10 × 8 in, 10 lb, zone 4, Priority Mail® — totals update live in the calculator.
Billed weight
10 lb
Dim weight
6 lb
Base (est.)
$17.27
Total (est.)
$17.27
We combine billable weight (actual vs dimensional for custom boxes), zone-based retail curves, optional Flat Rate packaging, and service-specific rules (Ground Advantage™, Priority Mail®, Express®, Media Mail®). The output is for planning and education—not a Click-N-Ship® total.
DIM lb = ceil(L × W × H ÷ 166)Flat Rate packaging in this tool uses modeled flat prices instead of DIM. Media Mail® omits DIM in the same way as a simplified teaching model—always validate with USPS for your exact SKU mix.
Fulfilling at scale? Pair this page with the supply chain efficiency calculator.
Build a custom calculatorIf the same item fits in a Priority Mail® Small Flat Rate Box and your zone band makes the flat price cheaper than weight-rated Priority, the flat option can reduce postage—test both paths in the calculator.
Illustrative total (defaults): $17.27
Adjust zones, Flat Rate packaging, and services—the card updates as you type.
Help your team quote postage before you pack the batch.
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