Jump starter size calculator
A 5.7L V8 gas engine needs roughly 350 cranking amps at freezing and about 490 at 0 F, so choose a jump starter its maker rates for at least 6.6L gas, typically a 1,500 to 2,000 peak amp class unit. A 6.7L diesel needs about double the cranking current.
A deeply flat battery absorbs some of the pack's current before the starter sees it, which is why the rating margin matters.
cranking amps = liters x 61 cubic inches x (2 for diesel) x temperature factor; buy a unit whose stated engine rating exceeds your engine by 15 percentPeak amp figures on jump starters are not a standardized measurement, so two 4,000A units can perform very differently. The engine size a maker states for its own unit (for example "up to 8.0L gas / 7.0L diesel") is a better comparison, and the tool ranks the products below by that.
Jump starters rated for this engine
Prices from Amazon at the time of writing; they change often.
TREKURE Portable Car Battery Jump Starter 4000A 16800mAh Jump Box, Car Battery Jumper...4,000A peak / 8L gas / 6.5L diesel / 16,800mAh$35.99Check price on Amazon
GOOLOO GP3000 Jump Starter, 3000A Peak Car Starter (9L Gas or 7L Diesel)3,000A peak / 9L gas / 7L diesel$59.96Check price on Amazon
Jump Starter with Air Compressor, BRPOM 8000A Portable Car Jump Starter (All Petrol/12L...8,000A peak / 12L diesel / 160 PSI / air compressor$62.99Check price on Amazon
GOOLOO A3 Pro 12V 3000A Portable Car Jump Starter with Air Compressor3,000A peak / air compressor$89.98Check price on Amazon
8000A 12V/24V Heavy Duty Jump Starter, Portable Battery Jump Box for Gas & Diesel...8,000A peak / 12V/24V$259.99Check price on Amazon
How many amps does my engine need to start?
Cranking amps at freezing and at 0 F, from roughly one amp per cubic inch of displacement for gas and about twice that for diesel. The last column is the rating class worth buying, with headroom for a deeply flat battery.
| Engine | Amps at 32 F | Amps at 0 F | Peak class |
|---|---|---|---|
| 1.0L motorcycle or small engine | 61 A | 85 A | 1,000A+ |
| 2.0L four-cylinder gas | 122 A | 171 A | 1,000A+ |
| 3.0L V6 gas | 183 A | 256 A | 1,000A+ |
| 3.6L V6 gas | 220 A | 308 A | 1,000A+ |
| 5.0L V8 gas | 305 A | 427 A | 1,500A+ |
| 5.7L V8 gas | 348 A | 487 A | 1,500A+ |
| 6.4L V8 gas | 391 A | 547 A | 2,000A+ |
| 7.3L V8 gas | 445 A | 624 A | 2,000A+ |
| 2.0L four-cylinder diesel | 244 A | 342 A | 1,500A+ |
| 3.0L V6 or inline-six diesel | 366 A | 513 A | 2,000A+ |
| 5.0L V8 diesel | 610 A | 854 A | 3,000A+ |
| 6.6L V8 diesel | 806 A | 1128 A | 4,000A+ |
| 6.7L diesel | 818 A | 1145 A | 4,000A+ |
| 7.3L V8 diesel | 891 A | 1247 A | 4,000A+ |
Why is peak amps a poor way to compare jump starters?
There is no single standard for how peak amps are measured on portable packs, so one maker's 4,000A can outperform another's 6,000A. What matters is the current a pack can hold for the several seconds a starter motor needs, and that figure is rarely printed.
The most useful number on the box is the engine size the maker rates the pack for, such as "up to 8.0L gas / 7.0L diesel". The products under the calculator are ranked against that stated rating, with a 15 percent margin for cold and for batteries that are completely flat.
Frequently asked questions
What size jump starter do I need for a V8?
A 5.7L V8 draws roughly 348 cranking amps at freezing and about 487 at 0 F. Choose a pack its maker rates for at least 6.6L gas, which in practice is a 1,500 to 3,000 peak amp class unit. Bigger V8s such as the 6.2L and 7.3L need a rating of 7.2L and 8.4L gas.
What size jump starter do I need for a diesel truck?
A 6.7L diesel needs roughly 818 cranking amps at freezing, about double a gas engine of the same size, and more in cold weather because the oil is thicker. Look for a pack rated by its maker for at least 7.7L diesel; units advertised for "all gas and up to 12L diesel" cover every pickup diesel.
Can a jump starter be too big for my car?
No. A jump starter supplies current on demand; the starter motor draws only what it needs. A larger pack is heavier and costs more, but it will not harm a small engine, and the extra capacity helps in cold weather or with a completely flat battery.
Does cold weather change what jump starter I need?
Yes, twice over. Cold thickens engine oil, raising the current needed to crank, and it cuts the output of both the car battery and a lithium jump pack. At 0 F cranking demand is roughly 40 percent higher than at freezing. Keep the pack indoors in winter and buy a rating with margin.