Postage Calculator
Estimate postage costs based on package weight, dimensions, and destination.
Supports both imperial and metric units.
Estimated Postage Cost
Postage cost depends on weight, size, and destination. Carriers use the greater of actual weight or dimensional weight.
Dimensional Weight (lbs) = (L × W × H) / 139
Billable Weight = max(Actual Weight, Dimensional Weight)
USPS First-Class Mail (2025):
- Letters (1 oz): $0.73
- Letters (each additional oz): $0.28
- Large envelopes (1 oz): $1.50
- Packages up to 13 oz: $4.00–$8.00
USPS Priority Mail (2025 approximate):
- Flat Rate Small Box: $10.40
- Flat Rate Medium Box: $17.10
- Flat Rate Large Box: $22.45
Domestic vs International:
- Domestic packages are generally 2–5× cheaper than international
- International First-Class starts around $15 for small packages
Tips to save on postage:
- Use flat-rate boxes for heavy, compact items
- Compare USPS, UPS, and FedEx rates online
- Print postage online for discounted rates
- Use the smallest appropriate packaging