If you’re shopping for a 1-inch furnace filter, you’ll see MERV 11 and MERV 13 on a lot of boxes. Here’s the practical difference — without the medical hype.
Size first. Always.
Wrong size is more expensive than the wrong MERV. Pull the old filter. Read the printed size on the frame, or measure shorter × longer × thickness. Then order the matching pack.
Step-by-step: How to measure your furnace filter.
What MERV means for a 1-inch pack
MERV is a rating for how fine the filter media is. On common 1-inch residential packs:
- MERV 11 — denser than basic fiberglass; a common everyday choice for many homes.
- MERV 13 — denser media than MERV 11 on the same footprint. More resistance to airflow is possible if your system wasn’t designed for it.
Rule of thumb: match what your furnace or air handler manual allows. Don’t jump denser “just because.” If the manual says MERV 11 (or lower), stay there.
When people pick MERV 13
Some homeowners choose MERV 13 when their equipment supports it and they want denser media on a standard 1-inch swap. That is a hardware preference — not a medical claim, not allergy treatment, and not a 99.9% promise.
Swap cadence
Many homes swap 1-inch filters on a printed interval around every 90 days (sooner if it’s visibly loaded or the manufacturer says otherwise). A 6-pack is there so you’re not hunting big-box leftovers at 9pm.
What we sell
Caliza Home is a small SoCal shop. Our HVAC 6-packs use Aerostar filters from the Aerostar line in Orlando, Florida when we name a factory city. That is not a blanket “Made in USA” claim on every SKU on the site.
More answers: Filter FAQ · Shop filters.
You dirty it. We filter it.