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Tools

Free tools. Zero sign-up.

Small calculators I built for my own work and left online. No sign-up, no email wall, nothing stored. Each one shows its formula so you can check the number yourself.

All tools

Business

Margin calculator

Profit margin, markup, and discount in one tool. Enter cost and price to get the margin, or work backwards.

margin = (price − cost) ÷ price × 100

Marketing

CPM calculator

Cost per thousand impressions, solved any direction. Plug in two of cost, impressions, or CPM.

CPM = spend ÷ impressions × 1,000

SaaS

LTV : CAC calculator

Customer lifetime value, CAC payback, and the 3:1 ratio benchmark for SaaS, worked out instantly.

ratio = LTV ÷ CAC (aim ≥ 3:1)

Most of these have a companion guide on the blog with 2026 benchmarks and the formula worked through end to end.

Contact

Get in touch.

If you're building something and want a hand, write to me. Same if you just want a second opinion on an architecture decision.

me@nayeemurrahman.com

Prefer to talk? Grab 15 minutes in my calendar.

© 2026 Nayeemur Rahman. All rights reserved.

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