How we check our numbers

Every calculator on ToolsNode shows its work. That's the whole idea. You shouldn't have to trust a black box with your print quote or your ad budget, so here's exactly how we build and verify each tool.

Where the formulas come from. We start with the standard formula for the job — the kind you'd find in a print production handbook, a carrier's published rate guide, or a platform's own help docs. Then we write it out on the page, in plain words, right next to the calculator. If a tool uses dimensional weight, you'll see the divisor stated. If it estimates a fee, you'll see the percentage and the date we last confirmed it.

Assumptions are labeled, not buried. Most calculators need default values — a typical Shopify plan rate, a standard ink coverage figure, an average email open rate. We mark every default as a default and tell you what it's based on. Change any of them; the math updates instantly. A default is a starting point, not a fact about your business.

Sources carry dates. Any preset rate or benchmark on this site comes with a source and a review date, shown on the page. Rates change — platforms update fee structures, carriers revise divisors — so each dated figure has a shelf life. If a figure passes its review date without re-verification, we disable the preset rather than show you something stale. You can always type in your own number instead.

How review works. Each tool is re-checked on a schedule: fee and rate-based calculators monthly, formula-based calculators quarterly. A review means opening the source, re-running the calculation by hand against it, and updating the review date you see on the page. If the source changed, the formula changes with it, and the date tells you when.

What we don't do. We don't estimate what we can't source. If a marketplace doesn't publish its fee breakdown, we say so on the page instead of guessing. We don't present averages as guarantees — a "typical" influencer rate is a starting point for negotiation, not a quote.

Corrections. Found a formula that's wrong or a rate that's out of date? Email [email protected] with the tool name and what you spotted. We fix verified errors within 48 hours and update the review date so you can see it happened.

Last updated: October 4, 2026