Filter Subscriptions vs Buying Bulk — 12-Month Cost Math

The spreadsheet (pet household, MERV 11 16×25×1)

Assumptions: 5 changes/year (72-day interval), Amazon list prices May 2026.

Purchase style	Annual filters	Approx. annual cost
30-day auto-ship (12 boxes)	12	$216–264
60-day auto-ship (6 boxes)	6	$108–132 (often still early)
6-pack bulk, buy twice	10–12 on hand, 5 used	$95–125
Big-box 2-pack × 3 trips	6	$78–102 (if you actually need 5)

When subscriptions are fine

• Vacation home you visit quarterly — set-and-forget
• Landlord supplies filters to tenants on a fixed schedule
• You truly change exactly on the ship date (rare with pets)

When bulk wins

• You already log pressure or visual loading
• Pets or pollen shorten cycles unpredictably
• You have closet space for a six-pack

Fridge filters — different trap

Fridge cartridges often push 6-month subs while light-use homes run 9 months. Buying a two-pack when taste changes beats annual subs that ship winter filters you stack in a drawer.

Action step

1. Count changes you made last year (honest count).
2. Compare to ship frequency on your sub account.
3. Switch to bulk for HVAC; keep one spare fridge cartridge on shelf.

Calendar: Replacement calendar.