Editorial methodology
Every calculator on eComCalculators.io is built and maintained by performance marketers and DTC operators who use these tools in their own work. This page documents how we ensure accuracy, when we update calculations, and how to flag errors.
Where the formulas come from
Foundational calculations (ROAS, contribution margin, LTV:CAC, payback period) come from established unit economics literature — most notably Bain & Company, McKinsey & Company, and the IPA's The Long and the Short of It for marketing efficiency frameworks. Where multiple definitions exist (CAC vs CPA, LTV with vs without margin), we explicitly note which version we're using and why.
Platform-specific calculations (Amazon FBA fees, Shopify Plus pricing, TikTok Shop commissions, Klaviyo tiers, AliExpress shipping) are sourced from current published rate cards as of the calculator's last-updated date. Where rates vary by category or region, we use the most common values for US-based DTC and note the variance.
Industry benchmarks cited in the explanations come from a combination of published reports (Shopify, Klaviyo, Triple Whale, NielsenIQ, IAB) and our team's direct observation across hundreds of DTC accounts. Where benchmarks vary widely by category, ranges are given rather than single numbers.
Review cycles
Quarterly review: calculators that touch fast-moving platforms (Amazon FBA fees, Meta CPM ranges, Shopify Plus pricing, Klaviyo and Mailchimp tiers, AliExpress shipping options, TikTok Shop commission rates) — anything where the underlying inputs change with platform pricing decisions.
Annual review: calculators on durable economics (ROAS, LTV:CAC, contribution margin, breakeven analysis). The math doesn't change but benchmarks and typical ranges shift slowly with the industry.
Last-updated date: the date shown under each calculator's title reflects the most recent review. If a calculator hasn't been reviewed in over a year, we flag it for the next quarterly batch.
Accuracy standards
Every calculator is hand-tested with sample inputs against an independent spreadsheet calculation before launch. Where formulas have multiple valid forms (e.g., LTV with or without refund adjustment), we document which version is in use and explain the trade-offs in the About copy.
For benchmarks and typical ranges given in the About copy, we cite ranges rather than single numbers when the underlying data varies by >15% across reputable sources. We avoid presenting one "right" answer when reasonable practitioners disagree.
We never publish a calculator that we wouldn't use ourselves on real accounts.
Corrections
If you spot a calculation error, an outdated benchmark, or believe a formula is misapplied, please contact us or use the "Report an issue on this page" link in the footer of any calculator. We aim to triage reports within 48 hours and ship corrections within a week.
When a calculator is materially corrected (formula change, not just a benchmark update), the calculator's last-updated date is bumped and a brief changelog is added in the next quarterly review.
No fabrication
We don't fabricate testimonials, fake "as featured in" logos, or invent customer counts. The site is what it is: a free collection of calculators built by people who use them. If something looks like a marketing claim, it's a quote from a published source or our own measured observation.
Independence
The site is funded by occasional affiliate links to tools we already recommend (Klaviyo, ShipBob, etc.) where it costs you nothing extra. We never recommend a tool we don't actually use. There are no sponsored category placements, no pay-for-position in search rankings, and no editorial decisions tied to commercial relationships. If we ever do paid sponsorships, they will be disclosed inline.
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