Shipping markup calculator: check your 3PL postage charges
Free shipping markup calculator. Enter carrier cost and billed postage, or paste a month, to see the actual markup, the allowed amount and the overcharge.
This shipping markup calculator compares what your 3PL billed for postage with what the carrier charged, and tells you the actual markup, the most your contract allows, and the overcharge. Check one label, or paste a whole month of shipments as two columns. A few points above the contract looks small on one label and adds up quickly across hundreds of them.
How to use the calculator
For one shipment, enter:
- Carrier cost: what the carrier charged for the label.
- Amount billed: the postage on your 3PL invoice for that shipment.
- Markup allowed: the percentage in your contract, for example 8 for "carrier cost plus 8%".
For many shipments, paste two columns into the box, one shipment per line: carrier cost first, then billed. Commas, tabs, semicolons or spaces between the two numbers all work, so you can copy straight from a spreadsheet. When lines are pasted, the calculator uses them instead of the single-shipment fields.
Where to find the carrier cost. Some 3PL invoices include a carrier cost column next to each label. If yours does not, ask your 3PL for a shipment report with the carrier charge per tracking number. Your contract may also define "cost" in a specific way, for example the warehouse's own discounted rate or a published rate. Read that clause before you compare.
The formula
For each shipment:
- Allowed = carrier cost × (1 + allowed markup ÷ 100), rounded to the cent
- Overcharge = billed − allowed, if above zero
For the whole set:
- Actual markup % = (total billed ÷ total carrier cost − 1) × 100
- Allowed total = total carrier cost × (1 + allowed markup ÷ 100)
- Total overcharge = the sum of each shipment's overcharge
Shipments billed at or under the allowance count as zero. They do not offset overcharges on other lines, because each label is a separate charge.
Worked example
Ridgeline Fulfillment, a made-up warehouse, bills Juniper & Pine, a made-up brand, at carrier cost plus 8%. Here are five labels pasted from a made-up invoice:
| Carrier cost | Billed | Allowed (cost × 1.08) | Overcharge | Markup |
|---|---|---|---|---|
| $9.34 | $10.46 | $10.09 | $0.37 | 12.0% |
| $7.31 | $8.19 | $7.89 | $0.30 | 12.0% |
| $12.50 | $13.50 | $13.50 | $0.00 | 8.0% |
| $15.00 | $16.80 | $16.20 | $0.60 | 12.0% |
| $6.25 | $6.75 | $6.75 | $0.00 | 8.0% |
| $50.40 | $55.70 | $54.43 | $1.27 | 10.5% |
Checking the first line: $9.34 × 1.08 = $10.0872, which rounds to $10.09. Billed $10.46, so the overcharge is $10.46 − $10.09 = $0.37. The actual markup is $10.46 ÷ $9.34 − 1 = 12.0%.
For the set: $55.70 ÷ $50.40 − 1 = 10.5%. The allowed total is $50.40 × 1.08 = $54.432, or $54.43, and the overcharge is $1.27.
A dollar on five labels looks small. Across three months of orders it is not: in the made-up sample audit, postage billed at 12% instead of 8% came to $417.58, the largest finding.
What the result means
- A steady markup above the contract on most lines, like the 12% here, usually means the billing system has the wrong markup set up. It is a certain finding, and a setup error like this repeats every month, so check earlier invoices too.
- A blended markup between the allowed figure and something higher, like the 10.5% here, means some shipments are marked up correctly and others are not. Look for a pattern by carrier, service or date.
- Lines with a big markup and a surcharge need a second look. Whether the markup also applies to surcharges, such as residential delivery or fuel, depends on your contract. Our pages on the residential surcharge and fuel surcharge explain how those are billed.
- No overcharge but high postage points to the label itself: the service chosen or the billed weight. Check box sizes with the dimensional weight calculator.
For the full picture of how markups are written into 3PL contracts, read our guide to shipping markup. When you have the totals, the credit request email template turns them into a dispute.
Check every label on every invoice
3PL Checker's free audit compares the postage on every shipment with the carrier cost and the markup in your contract, along with every other charge on the bill. A person reviews each finding, and you get the evidence and a credit request ready to send.
Questions
What does shipping markup mean?
It is the amount a 3PL adds on top of what the carrier charges for a label. A contract might say postage is billed at carrier cost plus a set percentage.
What is the average shipping markup?
There is no reliable published average, and it varies by contract. The number that matters is the markup in your own agreement, which this calculator checks against what you were billed.
How do you calculate a markup on shipping cost?
Markup % = (billed ÷ carrier cost − 1) × 100. The most you should be billed is carrier cost × (1 + allowed markup %), and anything above that is an overcharge.