Estimate postage costs based on mail class, weight, and zone.
Standard Letter (First-Class)
Large Envelope / Flat
Postcard
Package (USPS Ground Advantage™)
Package (Priority Mail®)
Priority Mail Flat Rate Envelope
Priority Mail Flat Rate Box (Medium)
Priority Mail Flat Rate Box (Large)
Pounds (lbs)
Ounces (oz)
Zone 1 & 2 (Local / Close radius)
Zone 3 (Approx. 151-300 miles)
Zone 4 (Approx. 301-600 miles)
Zone 5 (Approx. 601-1000 miles)
Zone 6 (Approx. 1001-1400 miles)
Zone 7 (Approx. 1401-1800 miles)
Zone 8 (1801+ miles / Cross Country)
Understanding US Postal Rates in 2024
Calculating postage for the United States Postal Service (USPS) involves several variables. Unlike simple flat fees, modern shipping costs are determined by the dimensions, weight, speed (mail class), and distance (zone) the package travels.
Note on 2024 Updates: As of July 2024, the price of a First-Class Mail Forever® stamp is $0.73. USPS Ground Advantage™ has replaced First-Class Package Service and Retail Ground as the standard economy shipping option.
Key Factors Influencing Your Rate
Mail Class: This determines the speed of delivery. First-Class Mail is for letters under 3.5 oz. Ground Advantage is the standard 2-5 day service for packages. Priority Mail offers 1-3 day delivery.
Weight: Rates are often calculated in ounces for light items and pounds for heavier packages. Always round up to the nearest ounce or pound depending on the service.
Zone: The USPS divides the US into "Zones" based on the distance from the origin zip code. Zone 1 is local, while Zone 8 is cross-country. The further the zone, the higher the cost.
How to Determine Your Zone
Zones are dynamic based on where you are shipping from. A package shipped from New York to California is likely Zone 8. A package shipped from New York to New Jersey is likely Zone 1 or 2. You can find your exact zone using the USPS Domestic Zone Chart, but our calculator provides estimates based on standard mileage bands.
Retail vs. Commercial Pricing
The rates calculated above represent Retail Rates (what you pay at the Post Office counter). Commercial shippers who print labels online (via platforms like eBay, Etsy, or shipping software) often receive "Commercial Base Pricing," which can be significantly cheaper than the retail rates shown here.
Package Dimensions Matter
While this calculator focuses on weight and distance, extremely large or lightweight-but-bulky packages may be subject to "Dimensional Weight" (DIM weight) pricing. If a box is very large but light, the USPS charges based on the volume of the box rather than the scale weight.
function toggleInputs() {
var type = document.getElementById('mailType').value;
var weightDiv = document.getElementById('weightContainer');
var zoneDiv = document.getElementById('zoneContainer');
// Logic to show/hide fields based on mail type
if (type === 'priority_flat_env' || type === 'priority_flat_med' || type === 'priority_flat_lrg' || type === 'postcard') {
weightDiv.style.opacity = '0.5';
weightDiv.style.pointerEvents = 'none';
// Flat rates don't depend on zone for price, except specifically Regional boxes (not covered) or very specific edge cases.
// Standard Flat Rate is nationwide price.
if(type !== 'postcard') {
zoneDiv.style.opacity = '0.5';
zoneDiv.style.pointerEvents = 'none';
} else {
// Postcards are fixed price regardless of zone
zoneDiv.style.opacity = '0.5';
zoneDiv.style.pointerEvents = 'none';
}
} else {
weightDiv.style.opacity = '1';
weightDiv.style.pointerEvents = 'auto';
if (type === 'letter' || type === 'large_envelope') {
// Letters generally don't use zones for retail pricing (just weight)
zoneDiv.style.opacity = '0.5';
zoneDiv.style.pointerEvents = 'none';
} else {
zoneDiv.style.opacity = '1';
zoneDiv.style.pointerEvents = 'auto';
}
}
}
function calculatePostage() {
var mailType = document.getElementById('mailType').value;
var lbs = parseFloat(document.getElementById('weightLbs').value) || 0;
var oz = parseFloat(document.getElementById('weightOz').value) || 0;
var zone = parseInt(document.getElementById('zone').value);
var totalOz = (lbs * 16) + oz;
var resultDiv = document.getElementById('postage-result');
var cost = 0;
var message = "";
var detail = "";
// Rate Constants (Estimates July 2024)
var stampPrice = 0.73;
var addOzPrice = 0.24;
var largeEnvBase = 1.50;
var postcardPrice = 0.56;
// Priority Flat Rates (Retail)
var pFlatEnv = 9.85;
var pFlatMed = 18.40;
var pFlatLrg = 24.75;
// Reset display
resultDiv.style.display = 'block';
resultDiv.innerHTML = "";
// Logic Engine
try {
if (mailType === 'postcard') {
if (totalOz > 1) { // Oversized for postcard logic usually, but keep it simple
throw "Postcards generally must be cardstock and standard size (max 6 inches long). If larger/heavier, select Letter.";
}
cost = postcardPrice;
message = "Standard Postcard Rate";
}
else if (mailType === 'letter') {
if (totalOz > 3.5) {
throw "Letters over 3.5 oz must be shipped as a Large Envelope (Flat).";
}
// Base + (Ceiling(TotalOz – 1) * 0.24)
var chargeableOz = Math.ceil(totalOz);
if (chargeableOz 13) {
throw "Large Envelopes over 13 oz must be shipped as a Package (Ground Advantage or Priority).";
}
var chargeableOz = Math.ceil(totalOz);
if (chargeableOz 1120) throw "Packages over 70 lbs cannot be mailed via USPS."; // 70lbs * 16oz
var weightLbsCeil = Math.ceil(totalOz / 16);
// If under 1 lb (15.999 oz), pricing is by ounce tier (4, 8, 12, 15.999)
// For simplicity in this static calculator, we will approximate logic:
var baseRate = 0;
if (totalOz <= 15.99) {
// Under 1 lb simplified tiers
// Zone 1/2 starts around $5.00 up to Zone 8 around $6.50
var ozTier = 0;
if (totalOz <= 4) ozTier = 5.00;
else if (totalOz <= 8) ozTier = 5.70;
else if (totalOz 1120) throw "Packages over 70 lbs cannot be mailed via USPS.";
var weightLbsCeil = Math.ceil(totalOz / 16);
// Base start for 1lb Zone 1 is approx $9.25. Zone 8 is approx $14.50
// This is a rough estimation formula for the 2024 curve
var basePriority = 9.25;
var perLbAdd = 2.10; // steep curve
var zoneMultiplier = 1.35; // steep curve for distance
var weightCost = (weightLbsCeil – 1) * perLbAdd;
var zoneAdder = ((zone – 1) * zoneMultiplier) * (1 + (weightLbsCeil * 0.15));
cost = basePriority + weightCost + zoneAdder;
message = "Priority Mail® (Weight/Zone Based)";
detail = "Zone " + zone + " | Weight: " + (totalOz/16).toFixed(2) + " lbs";
}
// Render Output
resultDiv.innerHTML = `
${message}
$${cost.toFixed(2)}
${detail}
*Estimates based on 2024 USPS Retail Rates. Final price may vary slightly at the counter due to dimensional weight or specific zip code routing.