Battery Atlas

Vehicles, trucks & marine

Cold Cranking Amps (CCA) Calculator

Estimate an orientative minimum CCA from engine displacement and compare it with your battery. The vehicle manufacturer's specification always takes priority.

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Formula

ci = L × 61.024
CCA(min, orientative) ≈ ci × k   (k = 1 gasoline, k = 2 diesel)
margin = CCA(battery) − CCA(required)

Worked example

2.0 L gasoline = 122 ci → ≈122 CCA orientative minimum. Most modern vehicles specify considerably more; use the OEM figure when available.

Limitations and warnings

  • The 1 CCA/ci (gasoline) and 2 CCA/ci (diesel) rule is an industry rule of thumb, not a standard. It ignores compression ratio, oil viscosity, starter design and electrical loads.
  • CCA cannot be converted to Ah (or vice versa) with a universal formula: they measure different things (cranking current vs stored charge).
  • SAE, EN, DIN and JIS ratings use different test conditions, so their numbers are not directly interchangeable.

Four values that are often confused

Nominal capacity (Ah)
Charge a battery delivers under rated conditions, usually over 20 hours (C20) at 25 °C.
Usable capacity
The part of the nominal capacity you can use without damaging the battery — about 50% for lead-acid, 80–90% for LiFePO4.
Cranking current (CCA)
Current deliverable for a short time in the cold to start an engine. It measures power, not stored charge, and cannot be converted to Ah.
Stored energy (Wh)
Ah × voltage. The right unit to compare batteries of different voltages.