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Free tools to grow and optimize your email marketing
Simple, accurate calculators and builders for small businesses, freelancers and newsletter creators. Everything runs in your browser — we never see what you type.
Popular tools
Pick one and get an answer in under a minute.
- Email Marketing ROI Calculator
Estimate revenue, profit, ROI and the break-even point for any campaign.
- Email Subject Line Preview
See roughly where phones and desktop inboxes cut off your subject and preview text.
- Newsletter UTM Builder
Build clean, correctly encoded tracking links — one at a time or a whole newsletter at once.
- Email List Growth Calculator
Simulate subscriber growth from signups and unsubscribe rate.
- Email Open Rate Calculator
Calculate open rate and learn why opens are an imperfect signal.
- SPF Record Syntax Checker
Check the syntax of an SPF TXT record and count DNS-lookup mechanisms.
- W-2 Code TT Calculator
Employers: calculate qualified overtime for 2026 W-2s, one week or a full year from CSV.
Why use these tools
Your data stays with you
Calculations happen on your device. No accounts, no forms sent to a server.
Formulas you can check
Every tool explains its math and its assumptions, so you know what the numbers mean.
Built for real campaigns
Handles the edge cases — zero costs, existing URL parameters, emoji in subject lines.