Blog
Guides to the math behind freelance rates, SaaS metrics, AI costs and everyday developer numbers. Every example is worked out step by step. For dated price changes, see News.
Freelancing3 min read
How to Calculate Your Freelance Hourly Rate (Without Guessing)
Start from the income you want to keep, add the costs an employer used to cover, and divide by the hours you can actually bill. Here is the full method with real numbers.
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SaaS metrics
LTV to CAC Ratio Explained, With the Math Behind It
LTV:CAC compares what a customer is worth with what it cost to win them. Here is how each side is calculated and why churn and margin move it so much.
2 min read
AI and APIs
How to Estimate LLM API Costs Before You Ship
API bills come from input and output tokens priced separately. With three numbers per request you can estimate a monthly bill and compare models before writing any code.
2 min read
Business math
Profit Margin vs Markup: The Difference That Changes Your Prices
Margin divides profit by the price. Markup divides it by the cost. Mix them up and a 50% target quietly becomes 33%.
2 min read
Developer basics
Mbps vs MB/s: Why Your Download Is Slower Than Your Plan
Internet plans are sold in megabits, downloads are measured in megabytes, and there are 8 bits in a byte. Here is how to estimate real download times.
1 min read
Business math
Percentage Change vs Percentage Points, and Why Losses Are Harder to Recover
A rate going from 4% to 5% rose by 1 percentage point, or by 25%. And a 50% drop needs a 100% rise to recover. Here is the math behind both.
1 min read
Business math
How to Remove VAT or Sales Tax From a Price (the Right Way)
Taking 20% off a price that includes 20% VAT removes too much. Here is why, and the one-line formula that gets it right every time.
1 min read
Developer basics
What 99.9% Uptime Really Means in Hours and Minutes
Each extra nine cuts allowed downtime by a factor of ten. Here is what three, four and five nines allow per year, month and day.
1 min read
SaaS metrics
Why Annualizing Monthly Churn Isn't Just Multiplying by 12
A 3% monthly churn rate doesn't compound to 36% a year. It compounds to about 30%. Here's the actual math, and why the difference matters.
2 min read