Methodology

The formulas, in full

There is nothing proprietary here and nothing withheld for the paid tier. These formulas are industry standard; the work is in applying them to costs people forget. The first one runs live in the break-even ROAS calculator; the rest power the other tools.

Break-even ROAS = price ÷ (price − landed − platform fee − payment fee − shipping − returns)

Break-even CPA = AOV × contribution margin

Target ROAS = 1 ÷ (contribution margin − target net margin)

MER = total revenue ÷ total ad spend

Landed cost = FOB + freight + duty + packing + clearance

Duty = customs value × combined rate

Two details that trip people up. Customs value is the goods plus buyer-paid packing invoiced separately — not landed cost, and not FOB alone. And returns are modelled as price × return rate × loss factor, where the loss factor is how much of the sale you fail to recover; set it to 1 for a full refund with no resale.

Where the tariff data comes from

Last verified 2026-10-02. MFN rates are pulled from the USITC Harmonized Tariff Schedule REST interface (2026 Revision 20), not transcribed from a secondary source.

We model duty as stacked layers rather than a single number, because that is what it is:

• MFN general rate — from the tariff schedule, per 8-digit HTS code when you pick one (the tariff calculator carries the consumer-goods chapters, with compound rates modelled and multi-part rates marked as unsupported), otherwise a representative rate per category. Source: USITC HTS
• Section 301, China lists — 7.5% (List 4A) or 25% (Lists 1–3), per HTS code, China only. Unaffected by the February 2026 Supreme Court ruling. Source: USTR
• Section 301, forced labor — effective 12:01am ET 24 July 2026. China, Vietnam, Thailand and Türkiye 12.5%; India, Mexico, Canada, Indonesia, Bangladesh, Cambodia and Pakistan 10%; the EU and Taiwan 10% net of MFN; Japan and Korea 12.5% net of MFN. USMCA-qualifying goods of Mexico and Canada are exempt. Source: USTR Docket 2026-0265/0266
• Section 338, Canada — an extra 50% on goods of Canada whose HTS code is on the lists in U.S. note 51 to Chapter 99, since 22 August 2026, widened on 15 September. It applies on top of MFN and the forced labor layer and to USMCA-qualifying goods as well. With a code we apply it per code; in category mode, when the category’s representative code is listed. Source: Proclamation 11065

The reason for the layered model is practical: when one layer changes — and several did during 2026 — you need to know which, and so do we, to tell you what moved.

What these estimates get wrong

This is the section most tools do not write. Ours has four entries and we would rather you read them before trusting a number.

1. Categories are not HTS codes. Duty applies per 10-digit code. Our ten categories are approximations built from a representative code, and the spread inside a category can be enormous — knit apparel ranges from 2.6% to 32%. Every result shows the representative code and the full range.
2. We model percentage duties only. Some headings carry a specific duty as well — cents per kilogram, cents per pair. Footwear, woven apparel and bags all contain such codes. Where they apply, our figure is too low, and the result says so.
3. Exemptions follow the HTS code. Annex I of the forced labor notice exempts civil aircraft parts, pharmaceutical-use articles, Section 232 goods (steel, aluminium, copper, vehicles, wood products such as upholstered wooden seating and kitchen cabinets) and charitable donations, and HTSUS note 52 lists further exempt codes. The calculator applies the note 52 exemptions when you pick an HTS code and flags codes on a Section 232 list; with only a category it applies none, so check the carve-outs for your own code.
4. Platform fees change without notice. TikTok Shop’s US referral fee moved during 2026 and public sources disagree about where it landed. Rather than pick one and present it as fact, we make it an input — your Seller Center is authoritative for your account.

Everything here is a planning estimate. Your customs broker’s classification determines what you actually pay, and no calculator changes that.

Category coverage

Ten categories, each with the HTS headings it covers, the representative rate we calculate with, and the real range across that heading.

Benchmark data

Last reviewed 2026-08-22. We show channel ROAS figures as a spread rather than a single median, because the published sources do not measure the same thing — some quote medians, some means, some loose ranges — and for the same channel they differ by more than 2×.

Presenting them as one authoritative number would be tidier and less true. The disagreement is itself the useful finding: no benchmark knows your cost structure, which is why the calculators derive your floor instead of comparing you to an average.

• TrueProfit — What's a Good ROAS in 2026
• EcomCalcTools — Ecommerce ROAS Benchmarks 2026 by Channel
• Hawky — What Is a Good ROAS for Ecommerce, 2026 Benchmarks

How often this is updated

When a rate changes, within 24 hours, and the verification date on every page moves with it. We do not refresh dates on a schedule to look active — a date here means someone checked the source that day.

Rate changes also get a changelog entry, so you can see what moved and when rather than finding your numbers quietly different.

Who makes this

RoasFloor is built and maintained by SuperLede, one person, who also writes the guides and keeps the duty tables current. It exists because the existing tools each solve half the problem. Tariff calculators tell you what you owe but nothing about whether the product still works. Profit trackers tell you what happened after you spent the money. Neither tells you what return you need before you commit.

No claim to being a customs authority — the sourcing discipline on this page is the substitute for credentials. Everything traces to a primary document, and where it cannot, that is stated rather than papered over. Corrections are welcome, particularly on classification.