1% Better Every Day Calculator
See the compounding power of small daily habits: how much better (or worse) you get by improving 1% a day for a year — 37.78× — or any rate and number of days.
How it works
Better: level = (1 + r)^days · worse: level = (1 − r)^days · days to double = ln 2 ÷ ln(1 + r)
The “1% better every day” idea, popularized by James Clear’s Atomic Habits, uses compound growth: 1.01³⁶⁵ ≈ 37.78, while 0.99³⁶⁵ ≈ 0.03. It is a metaphor for how small, consistent habits add up, not a literal law: real skills improve fast at first and then plateau, and you cannot measure most habits to the percent. The arithmetic is the same as compound interest, which is why the doubling time follows the rule of 70 (about 70 ÷ the daily percentage).
Worked example
Improving 1% a day for 365 days: 1.01³⁶⁵ = 37.78× where you started. Getting 1% worse each day: 0.99³⁶⁵ = 0.0255×. Without compounding, 365 × 1% would only add up to 4.65×. At 1% a day you double in 69.7 days.
Frequently asked questions
What is 1% better every day for a year?
1.01 raised to the 365th power, about 37.78 — almost 38 times better than where you started.
What is 1% worse every day for a year?
0.99 to the 365th power, about 0.03 — you would drop to about 3% of where you started.
Is the 1% rule realistic?
Not literally. Progress is uneven and slows as you improve. The math shows why consistent small actions matter, as in James Clear’s Atomic Habits.
How long does it take to double at 1% a day?
ln 2 ÷ ln 1.01 ≈ 69.7 days, close to the rule of 70.
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This calculator is for educational purposes. Double-check important results before acting on them.