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About this tool
Set engine air filter and cabin AC filter change intervals from your dust exposure, driving pattern and kilometres run.
The Air Filter Change Planner works out separate replacement schedules for the engine air element and the cabin (AC) filter by taking each one's normal-service interval — typically 20,000 km or 24 months for the engine filter and 15,000 km or 12 months for the cabin filter — and shortening it for dust exposure and driving pattern. Both are volume filters, so what loads them is the quantity of dirty air passed rather than distance alone, which is why a car on unpaved roads can exhaust an element in a fifth of its rated distance. It also gives an inspection interval, since a paper element should be checked several times over its life.
Open Air Filter Change Planner on AltFTool — it loads instantly in your browser.
Add your input to the workspace.
Adjust the options until the result looks right.
Copy or download the output and put it to work.
The engine element and the cabin filter have different intervals and different triggers.
Severe dust exposure shortens the interval to 40% of the normal figure, matching severe-service guidance.
Gives the distance at which to check and blow out the element between replacements.
The common normal-service figure is around 20,000 km or 24 months for the engine air filter and 15,000 km or 12 months for the cabin filter, whichever comes first. On genuinely dusty roads both need changing far sooner — inspection every 5,000 to 7,000 km is more realistic.
On a modern fuel-injected engine, barely. The engine management compensates for the restriction, so what you actually lose is wide-open-throttle power and acceleration, not steady-state mileage. The old rule that a clogged filter costs about 10% in fuel applies to carburetted engines, which had no such compensation.
A paper element can be tapped out and blown through gently from the clean side with low-pressure air, and doing that two or three times over the element's life is normal practice. Never wash a paper element or use a high-pressure jet — the media tears microscopically and then passes the grit it was fitted to stop.
Airflow from the vents drops noticeably, the AC feels weaker even though the gas is fine, and the blocked filter traps damp debris that produces the musty smell people blame on the AC itself. A badly clogged cabin filter also makes the blower motor work harder, which shortens its life.