This online calculator allows you to determine the different parameters involved in a voltage divider, as shown in the following diagram: 
Input Data
| +Vcc | Volts | |
| -Vcc | Volts | |
| R1 | Ohms | |
| R2 | Ohms |
Results
| Req | Ohms | |
| i | Milliamps | |
| Vout | Volts | |
| V1 | Volts | |
| V2 | Volts | |
| P1 | Milliwatts | |
| P2 | Milliwatts | |
| P1+P2 | Milliwatts |