Depends on the phone and the battery. During normal operation, the Candle Charger delivers a stead 500 mA at 5V. If your battery capacity is 1500 mAh, your phone will be fully charged in 1500 mAh/500 mA = 3 hours. Some common phones:
• iPhone 4: 1420 mAh, or 2.8 hr charge
• iPhone 5: ~1500 mAh (depends on version), or 3 hr charge
• iPhone 6: 1810 mAh, or 3.6 hr charge
• Samsung 6: 2550 mAh, or 5.1 hr charge
In some phones, internal circuitry limits the rate of charge. For example, in some iPhones tested the accepted current is limited to 450 mA. This will have a small impact on the charge time.