Tools
Every calculator here exists because an article needed one. You can read the piece that explains the model, then run your own numbers through it. Everything computes in your browser. Nothing is stored, nothing is sent anywhere, and there is no signup.
Investing
Investing articles401(k) Employer Match Calculator
Model a tiered employer match, find the exact contribution rate that captures all of it, and see in dollars what you give up by contributing less.
Open toolCompound Interest Calculator
Project what a starting balance plus monthly contributions becomes, in both nominal dollars and what it will actually buy.
Open toolDCF Valuation Calculator
Discount ten years of free cash flow to a per-share fair value, then flip the model around and read the growth rate the current price is already asking for.
Open toolPortfolio Rebalancing Calculator
Enter what you hold and what you want to hold. Get the exact dollar trades, plus a no-sell version that rebalances with new cash alone.
Open toolPosition Size and Risk Calculator
Work backwards from what you are willing to lose. Enter your account, your risk tolerance and your stop, and get the share count that makes the maths work.
Open toolEngineering
Tech articlesBig-O Complexity Calculator
Put a wall-clock number on a complexity class. Enter your input size and see which algorithms finish instantly, which finish overnight, and which never finish at all.
Open toolLLM API Cost Calculator
Price a feature before you ship it. Token counts and request volume in, monthly bill out, with prompt caching and batch discounts modelled properly.
Open toolUptime and SLA Calculator
Turn a number of nines into minutes of allowed downtime, then check whether your dependencies can actually support the promise you are making.
Open tool