Multi-Mode Percentage Calculator
Direct Percentage • Proportion • Percentage Increase & Decrease
📊 Percentage Calculator
What is X% of Y?
What is
% of
=30
X is what percentage of Y?
is what % of
=25%
Percentage Change (from X to Y)
From
to
=+50.00%
🛡️ 100% Client-Side Privacy Protection
All financial calculations and numerical conversions execute strictly within your local browser JavaScript engine. No figures or queries are ever transmitted over the network.
⚡ Instant Zero-Latency Execution
Direct IEEE-754 floating point arithmetic with zero server roundtrip latency for immediate reactive feedback.
Mathematical Specifications & Technical FAQ
How is percentage change calculated?
Percentage change is calculated using the formula: ((New - Old) / Old) * 100.
What happens if the starting value is zero?
Percentage change from zero is mathematically undefined, so the calculator reports a clear indicator.
Can I calculate negative percentage decreases?
Yes, negative percentage changes automatically display with a minus sign and appropriate styling.