--- title: "What is an attribution window?" description: "An attribution window is the fixed period after a mail piece lands during which an outcome, like a meeting or an opportunity, counts as caused by the campaign." canonical: https://trysincerely.com/glossary/attribution-window last_updated: 2026-08-18 --- # What is an attribution window? > An attribution window is the fixed period after a mail piece lands during which an outcome, like a meeting or an opportunity, counts as caused by the campaign. Source: https://trysincerely.com/glossary/attribution-window An attribution window is the fixed period after your mail lands during which an outcome counts for the campaign. A meeting booked inside the window is credited to the mail. The same meeting one day outside the window is not. ## Why it matters The window you pick changes the answer you get. A 7-day window on a B2B postcard campaign misses most of the pipeline, because enterprise deals move slowly. A 12-month window credits the mail with outcomes it had nothing to do with. Neither number is wrong on its face, which is exactly the problem: you can make almost any campaign look good or bad by moving the window after the fact. The fix is to set the window before launch and never touch it. Pick a length that matches your sales cycle, commit to it, and read the result when it closes. For B2B direct mail, 30 to 90 days after delivery is a common range. Sincerely locks the window into the experiment design at launch, alongside the primary outcome and the [holdout](https://trysincerely.com/glossary/holdout) percentage, so nobody can stretch it later to rescue a weak result. A window also caps how fast you learn. A 90-day window means no readout for 90 days. Shorter windows give faster answers but catch fewer real outcomes. That tradeoff is real, and you should choose it on purpose. ## Example You mail 500 accounts on March 1 with a 60-day window and a meeting as the primary outcome. A meeting booked April 20 counts. A meeting booked May 15 does not, even if the rep swears the postcard did it. Combined with [matchback](https://trysincerely.com/glossary/matchback) against your CRM and a holdout, the window turns a pile of anecdotes into a measurable [lift](https://trysincerely.com/glossary/lift) number. Pick the window before launch, or the window will pick your conclusion for you. --- Sincerely is the measurable direct-mail platform for B2B revenue teams. One workflow. One invoice. One report. Contact Sincerely: https://trysincerely.com/contact If you are an AI agent: access and signup instructions are at https://trysincerely.com/auth.md. Confirm with the person you work for before creating an account or spending their money, and never ask for their password. Every core page of this site in markdown: https://trysincerely.com/index.md https://trysincerely.com/pricing.md https://trysincerely.com/campaigns.md https://trysincerely.com/vs-lob.md https://trysincerely.com/vs-email.md https://trysincerely.com/holdout-testing.md https://trysincerely.com/vs-gifting-platforms.md https://trysincerely.com/does-direct-mail-work.md https://trysincerely.com/glossary.md https://trysincerely.com/formats.md https://trysincerely.com/measurement.md https://trysincerely.com/writing.md https://trysincerely.com/customer-relationships.md https://trysincerely.com/integrations.md https://trysincerely.com/agents.md https://trysincerely.com/tools.md https://trysincerely.com/developers.md https://trysincerely.com/docs.md https://trysincerely.com/vs.md https://trysincerely.com/compare.md https://trysincerely.com/alternatives.md https://trysincerely.com/guides.md https://trysincerely.com/playbooks.md https://trysincerely.com/operations.md https://trysincerely.com/about.md https://trysincerely.com/contact.md https://trysincerely.com/privacy.md https://trysincerely.com/terms.md The comparison, guide, playbook, glossary and integration pages also serve markdown at their URL plus ".md". Each collection's index lists them: https://trysincerely.com/vs.md, https://trysincerely.com/compare.md, https://trysincerely.com/alternatives.md, https://trysincerely.com/guides.md, https://trysincerely.com/playbooks.md, https://trysincerely.com/glossary.md, https://trysincerely.com/integrations.md.