Get the size right before you click "Buy."
Most one-star filter reviews trace back to fit, not MERV. Three minutes here saves a return — and a whistling blower.
Three minutes. Three steps.
This is the same flow our support team runs when you email us a photo — minus the wait.
Step 1 · Measure. Take your existing filter out (or peek into the slot). Use a tape measure. Write down width, length, depth — all in inches, to the nearest ¼″.
Step 2 · Match. Compare those three numbers to the actual dimensions printed on every ApexPuri product page. The closest match is your nominal size.
Step 3 · Verify (only if uncertain). If the match isn't clean — thick 4-inch media, odd dimensions, or a non-standard slot — email a photo of the frame edge to support@apexpuri.com and we'll confirm before you order.
Fit Check reference table
Match your measurement (in inches) to the closest nominal size in our catalog:
| If your filter measures (W × L × D) | Nominal size to order |
|---|---|
| 13.50 × 24.50 × 0.75 | 14×25×1 |
| 15.50 × 19.50 × 0.75 | 16×20×1 |
| 15.50 × 24.50 × 0.75 | 16×25×1 |
| 19.50 × 19.50 × 0.75 | 20×20×1 |
| 19.50 × 24.50 × 0.75 | 20×25×1 |
| 19.50 × 29.50 × 0.75 | 20×30×1 |
If your measurement is within ¼″ of one of these rows, that's your size. If not, send us a photo before ordering.
The Fit Guarantee
If you ordered the nominal size we recommended after running Fit Check and the filter doesn't seat securely in a standard residential return slot without modification, contact us within 30 days for a replacement or refund. No restocking fee. No return shipping. We don't make you pay to return a problem we caused.
→ Read full Fit Guarantee policy
Crushed in transit? One photo, one reply.
Filter packaging gets crushed in ~3–6% of industry shipments. We engineered ours down to under 0.4% with double-wall corrugate — but if yours arrives damaged, we don't ask you to send anything back.
What we need:
- One photo of the outer shipping box (showing the damage).
- One photo of the affected filter(s) so we can confirm.
- Your order number.
What you get:
- Free replacement of the affected pack(s), shipped same business day.
- No return label, no return shipping.
- Replies inside 1 business day.
FAQ
What is nominal vs actual size?
Nominal is a rounded label (16×25×1). Actual is the precise frame measurement (usually ~½″ smaller per dimension so the filter slides into the slot). Always buy to the actual dimensions of your slot, not the label.
How often should I replace?
Typical 1-inch pleated: every 90 days. Pets, pollen, or dusty environments: try 60 days. During indoor renovation: 30 days. Never wait until the filter visibly collapses or starts whistling.
Will MERV 13 hurt my HVAC?
It can increase static pressure versus MERV 8. If you notice longer run times or weak airflow at registers, step down one MERV level or confirm duct sizing with a licensed HVAC technician.
Which way does the arrow point?
Toward the blower. The arrow on the filter frame should point in the same direction as airflow through the return.
My slot measures between two nominal sizes — what now?
Always round DOWN to the smaller nominal. A slightly-loose filter can be foam-taped at one edge; an oversized filter can't be made to fit. Or send us a photo if you want a second opinion before ordering.
Can I run a 1-inch filter where a 4-inch was installed?
Sometimes — there's usually a "1-inch carrier" available for 4-inch cabinets, but it varies by brand. For 4-inch cabinets, send us two photos (front opening + side rail) before ordering. We'll confirm depth and rail clearance.
Do you ship to Canada?
Currently shipping to the contiguous U.S. only. Canada and Alaska/Hawaii are on the roadmap; add your zip to the email list to be notified when we open.
How do I cancel Subscribe & Save?
From any shipment email, click "Manage subscription". You can skip the next shipment, push it out 30 days, change cadence, or cancel entirely. No phone call required.