Car Fuse Size Guide

Find the right fuse for any circuit by wire gauge or component name. Includes fuse color codes and blown-fuse diagnosis steps.

Section 1 — Fuse Size by Wire Gauge (AWG)

Select Wire Gauge (AWG)

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Wire Gauge	Max Fuse Size	Typical Use
20 AWG	5A	Dome lights, small sensors
18 AWG	7.5A	Turn signals, gauges
16 AWG	10A	Radio, taillights
14 AWG	15A	Cigarette lighter, brake lights
12 AWG	20A	Accessory circuits, power windows
10 AWG	30A	Heated rear window, heavy accessories
8 AWG	40–50A	High-current accessories, amp power
6 AWG	60–80A	Main distribution, subpanel

Section 2 — Common Circuit Reference

Circuit	Typical Fuse	Notes
Cigarette lighter / 12V accessory	15–20A	Shared with accessory socket
Radio / head unit	10–15A	Plus separate memory fuse (5A)
Power windows	20–30A	Often one per door or one per side
Headlights	10–15A per circuit	Low and high beam often separate
Taillights / running lights	10A	May be combined with parking lights
Brake lights	10–15A	Check brake switch if fuse keeps blowing
Horn	10–15A	Short circuit often caused by worn horn button
Wipers	15–20A	Higher if rear wiper on same circuit
HVAC blower	20–30A	Blower motor can spike on high speed
Fuel pump	10–15A	Separate relay usually in underhood box
ECU / PCM	10–15A	Never substitute — use exact OEM spec
Interior lights	5–10A	Includes dome, map, and courtesy lights
Power seats	20–30A	Motors can draw heavily during adjustment
Heated seats	15–20A	Per seat or per side depending on design

Section 3 — How to Diagnose a Blown Fuse

Identify the fuse box location. Most vehicles have two: one under the dashboard (interior circuits) and one under the hood (high-current circuits). Your owner's manual has the fuse map.

Visual inspection. Pull the suspect fuse using the plastic fuse puller (usually stored in the fuse box lid). Hold it up to light — a blown fuse has a visible break or blackening in the metal strip inside.

Multimeter test. Set to continuity or resistance. Touch probes to the two metal prongs on top of the fuse. A good fuse beeps or reads near 0Ω. A blown fuse reads infinite resistance (open circuit).

Replace with the same amperage. Install an identical replacement — same amp rating and same fuse type. Turn on the circuit and watch for immediate re-blow.

Repeated blowing means a short circuit. If the replacement fuse blows immediately or within a short time, there is a wiring fault — a wire has chafed through its insulation and is shorting to ground. Diagnose with a wiring diagram before replacing any more fuses.

Never install a higher-amperage fuse as a "fix." Fuses protect the wiring, not the device. Using a 20A fuse in a 10A circuit means the wiring can overheat and catch fire before the fuse blows. Always use the correct amperage. If you cannot find the correct size, find and fix the root cause instead.

Blade Fuse Color Code (Standard ATC/ATO)

Color	Amperage	Type
Tan / Beige	5A	Mini, Standard, Maxi
Brown	7.5A	Mini, Standard
Red	10A	Mini, Standard, Maxi
Blue	15A	Mini, Standard, Maxi
Yellow / Gold	20A	Mini, Standard, Maxi
White / Clear	25A	Standard, Maxi
Green	30A	Standard, Maxi
Orange	40A	Maxi
Red (dark)	50A	Maxi
Blue (light)	60A	Maxi
Violet / Purple	80A	Maxi

Colors apply to standard blade (ATC/ATO), mini blade (ATM), and maxi blade (APX) fuses. Glass tube and bolt-down fuses use different identification systems.

Fuse Types Explained

Mini blade (ATM): Smaller version of the standard blade fuse. Common in late-model Japanese and European vehicles. Identified by the same color coding as standard blade fuses.

Standard blade (ATC/ATO): The most common type in North American vehicles since the 1980s. ATC is a closed-body version; ATO has an open body. Both are interchangeable.

Maxi blade (APX): Large blade fuse rated 20–100A. Found in underhood fuse boxes protecting high-current circuits like the alternator output, main relay, and ABS pump.

Glass tube (AGC/AGU): Older cylindrical glass fuses. Still found in some older vehicles and aftermarket audio amplifiers. Less common in new OEM applications.

Bolt-down (ANL / MIDI): High-current fuses (60–500A) secured with a bolt. Used in main battery cables, amplifier power runs, and auxiliary battery installations. ANL fuses are physically large and mounted in a separate holder near the battery.