US USPS Postage
US USPS Postage — US reference tool.
About US USPS Postage
USPS retail pricing is a base rate for the first weight increment plus a per-increment surcharge, and the increment differs by service: First-Class letters and flats step up by the ounce, while Ground Advantage and Priority Mail packages step up by the pound. Each service also has a hard ceiling — 3.5 ounces for a letter, 13 ounces for a flat — beyond which you must move to a heavier service rather than simply pay more. Extra services such as Certified Mail and Return Receipt are flat fees added per piece, not per pound, so they dominate the cost of a light letter and barely register on a heavy parcel.
Formulas
Letters and flats
Postage = base rate + (ceiling(ounces) - 1) x per-ounce step
Packages
Postage = base rate + (ceiling(ounces / 16) - 1) x per-pound step
Mailing total
Total = (postage + add-on fees) x number of pieces
Worked example
With the default values below, US USPS Postage returns Postage per Piece of $1.01. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Mail serviceone of First-Class Letter (up to 3.5 oz), Large Envelope / Flat (up to 13 oz), USPS Ground Advantage package, Priority Mail package
- First-Class Letter (up to 3.5 oz)
- Weightaccepts 0.1–1,120 oz
- 2 oz
- Number of piecesaccepts 1–10,000
- 1
- Add-on servicesone of None, Certified Mail, Certified Mail + Return Receipt, Signature Confirmation
- None
Results
- Postage per Piece
- $1.01
- Total for This Mailing
- $1.01
- Add-on Services per Piece
- $0.00
- Weight Check
- Within the weight limit for the selected service
Step by step
- 1Values used
- 2Letters and flats
- 3Packages
- 4Mailing total
- 5Postage per Piece= 1.01
- 6Total for This Mailing= 1.01
- 7Add-on Services per Piece= 0.00
- 8Weight Check= Within the weight limit for the selected service
Assumptions and limits
- The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
- Approximate USPS retail reference rates for budgeting only. Actual postage depends on current published rates, zone, dimensions, shape surcharges and non-machinable status. Verify with the official USPS Postage Price Calculator before printing labels or committing to a mailing budget.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Approximate USPS retail reference rates for budgeting only. Actual postage depends on current published rates, zone, dimensions, shape surcharges and non-machinable status. Verify with the official USPS Postage Price Calculator before printing labels or committing to a mailing budget.
Frequently Asked Questions
Why did my letter jump a price tier at exactly 1 ounce?
USPS charges by whole ounces, rounding up. A letter weighing 1.1 ounces costs the same as one weighing 2.0 ounces. Weigh mail before adding an extra sheet — one page can cost you a full additional ounce increment.
When is Ground Advantage cheaper than Priority Mail?
Ground Advantage has a much lower base rate and a gentler per-pound step, so it wins on price for almost any weight. Priority Mail buys speed (1-3 days versus 2-5) and includes higher default insurance, not a better rate.
Are these the exact rates I will be charged?
No. They are approximate retail reference rates and USPS revises them at least annually, with different Commercial and Priority Mail Cubic pricing available to volume shippers. Confirm the current figure at a Post Office or with the official USPS Postage Price Calculator.
Related Calculators
United States specifics
- Currency
- $ USDUS Dollar
- Region
- North America
- Country code
- US
- Amounts look like
- $1,234,567.89
- Dates look like
- Mar 9, 2026
- Units
- imperialWeek starts Sunday
In United States, imperial units are in everyday use.
Results on this page are expressed in USD (US Dollar). Figures are estimates for general planning — confirm current rates and thresholds with the relevant United States authority before relying on them.