All tools & calculators

These are simple one‑page tools. No login. No sign‑up. If you find something confusing, use the feedback button on any page.

Generate a professional sick day email you can copy‑paste.
Quick checks + red flags to look for before you click.
Convert salary to hourly (and back) with realistic hours.
Rough after‑tax take‑home estimate.
Estimate payoff time and interest.
Back‑of‑napkin affordability estimate.
Estimate monthly car payments.
Split a bill and tip quickly.
BMI in metric or US units.
Age in years, months and days.
Compute your current grade and what you need to pass.
Slope from two points.
Compress images for web & social. Crop + zoom included.
Printable monthly and yearly calendar (2025+).

How to pick the right tool

Most tools here are intentionally simple. If you need a quick estimate, start with the calculator and then read the “how it works” section to understand the assumptions.

Categories

  • Work & money: salary/hourly, take‑home pay, loan payoff, car loan payment, home affordability
  • Health: BMI
  • School & math: grade calculator, slope calculator
  • Everyday: age calculator, tip split
  • Email & safety: sick day email generator, “is this email sketchy?”

If you’re unsure which one to use, start with the tool that matches the question you’re trying to answer, then follow the related guide links on the page.

Quality checks

Tools are tested with a few known examples and edge cases (like zero rates, vertical slopes, and empty inputs). If something behaves unexpectedly, let us know and include the exact numbers you used.

Need context?

If a result surprises you, check the related guide or the “how it works” section on the tool page. That’s where assumptions and limitations are listed.

How tools are updated

We periodically revise calculators for clarity and edge cases (like zero rates, rounding, and unusual inputs). If something is confusing, it’s a signal the page needs better explanations.

FAQ

  • Why do some tools show “estimates”? Real‑world rules vary (fees, taxes, rounding, lender rules). Tools show the basic math and the assumptions.
  • Can I use these on mobile? Yes — pages are designed to work on phones and desktops.
  • Where’s the formula? Most calculators include it in the “how it works” section.

About estimates

Many tools show estimates because the “real” answer depends on details outside the calculator (local tax rules, fees, rounding policies, lender rules, and more). Use the tool to understand the math, then confirm with the official source.