What sample size calculator should I use?
Muhammed Tüfekyapan
Founder & CEO
TL;DR - Quick Answer
Complete Expert Analysis
Comprehensive Sample Size Calculation Guide
Determining the right sample size is crucial for conducting statistically valid A/B tests and making data-driven decisions in e-commerce optimization.
Key Sample Size Calculation Components
| Variable | Description | Typical Range |
|---|---|---|
| Confidence Level | Statistical reliability of results | 90-99% (95% recommended) |
| Current Conversion Rate | Baseline performance metric | 1-10% for most e-commerce |
| Minimum Detectable Effect | Smallest meaningful change | 10-20% improvement |
| Statistical Power | Probability of detecting an effect | 80-90% |
Recommended Sample Size Calculators
Free Online Tools
- ✓Optimizely Sample Size Calculator
- ✓VWO Statistical Significance Calculator
- ✓AB Testguide Sample Size Calculator
- ✓Google Optimize Sample Size Calculator
Advanced Statistical Software
- ✓R Statistical Programming Language
- ✓SPSS Sample Size Calculator
- ✓G*Power Statistical Software
Step-by-Step Calculation Process
1. Determine Current Conversion Rate
Calculate your baseline conversion rate by dividing total conversions by total visitors.
Conversion Rate = (Total Conversions / Total Visitors) × 100%2. Set Minimum Detectable Effect
Choose the smallest improvement that would be meaningful for your business.
- Low Traffic Sites: 20-30% improvement
- High Traffic Sites: 10-15% improvement
- Conversion Optimization: 5-10% improvement
3. Select Confidence Level
Choose statistical significance level. 95% is standard for most e-commerce tests.
- 90%: Less strict, faster results
- 95%: Balanced approach (recommended)
- 99%: Most conservative, requires larger sample
Automate Testing with Growth Suite
Growth Suite simplifies A/B testing by automatically calculating optimal sample sizes based on your store's unique conversion dynamics. The platform tracks visitor behavior, predicts purchase intent, and provides real-time statistical significance calculations. By integrating behavioral tracking with testing methodologies, Growth Suite ensures you're making data-driven decisions without complex manual calculations.
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With over a decade of experience in e-commerce optimization, Muhammed founded Growth Suite to help Shopify merchants maximize their conversion rates through intelligent behavior tracking and personalized offers. His expertise in growth strategies and conversion optimization has helped thousands of online stores increase their revenue.
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