Windshield Washer Fluid Mix Calculator
Calculate the right mix of windshield washer concentrate and water for your tank size and desired freeze protection level.
Washer Fluid Mix
Windshield washer fluid mixing determines the right ratio of concentrate to water based on the freeze protection you need.
Concentrate Amount = Tank Size × Concentration Ratio
Water Amount = Tank Size - Concentrate Amount
Typical mix ratios:
| Freeze Protection | Concentrate | Water |
|---|---|---|
| Above 32°F / 0°C (summer) | 25% | 75% |
| Down to 20°F / -7°C | 40% | 60% |
| Down to 0°F / -18°C | 50% | 50% |
| Down to -20°F / -29°C | 60% | 40% |
| Down to -40°F / -40°C | 70% | 30% |
Standard washer fluid tank sizes:
- Most cars: 0.75–1 gallon (2.8–3.8 liters)
- SUVs/Trucks: 1–1.5 gallons (3.8–5.7 liters)
- Vans: 1–1.25 gallons (3.8–4.7 liters)
Tips:
- Never use plain water — it freezes and grows bacteria
- Pre-mixed washer fluid is convenient but costs more per gallon
- In summer, you can use a weaker mix (more water)
- Do not mix different brands of concentrate — chemicals may react
- Rubbing alcohol + water + dish soap works in a pinch but can damage paint finish