PC Water Cooling Flow Rate Estimator
Thermal Design Power of your processor.
TDP per Graphics Card.
1°C (Extreme Performance)
2°C (High Performance)
3°C (Balanced)
5°C (Silent / Low Flow)
Temp difference between loop inlet and outlet.
Distilled Water (Pure)
Premix / Coolant (Standard)
Heavy Glycol Mix
Please enter valid positive numbers for Wattage.
Calculation Results
Total Heat Load:
0 W
Target Coolant Temp Rise:
2 °C
Required Flow (LPH):
0 L/h
Required Flow (GPM):
0.00 GPM
Recommendation:
About Water Cooling Flow Rates
Understanding flow rate is critical for optimizing a custom PC water cooling loop. The primary goal of the coolant is to transport heat from your components (CPU, GPU) to the radiators. The speed at which the water moves (flow rate) determines how efficiently this heat is transported and how much the water temperature rises while passing through the blocks.
How This Calculator Works
This calculator uses the thermodynamic formula Q = m × Cp × ΔT to determine the necessary flow rate based on your hardware's heat output.
- Q (Heat Load): The total power (in Watts) generated by your CPU and GPUs.
- Cp (Specific Heat): The capacity of the fluid to hold heat. Pure water is approximately 4186 J/kg°C, while glycol mixtures are lower.
- ΔT (Delta T): The temperature difference of the water between entering and exiting the blocks.
Interpreting the Results
The calculation tells you the minimum flow rate required to ensure the water does not heat up by more than your target ΔT while passing through the components.
Common Flow Rate Targets:
- 0.5 GPM (~115 L/h): The generally accepted "safe minimum." Below this, air bubbles may get trapped in blocks, and heat transfer efficiency drops significantly.
- 1.0 GPM (~225 L/h): The "gold standard." At this rate, you achieve diminishing returns on thermal performance. Going higher yields very small temperature improvements.
- High Flow (>1.5 GPM): Useful for complex loops with high restriction or for extreme overclocking scenarios where every degree counts.
Why Delta T Matters
If your flow rate is too low, the water stays inside the CPU/GPU block longer, absorbing more heat. This causes the water exiting the block to be significantly hotter than the water entering it. A high water Delta T means your components at the end of the loop receive warmer water, reducing cooling efficiency. By increasing flow, you reduce this temperature gap, ensuring all components receive coolant at roughly the same temperature.