One-line verdict

Ideal for families in small kitchens needing to cook multiple dishes at once, but requires frequent shaking for even cooking unlike wider dual-basket models.

How it compares

vs Ninja Double Stack XL SL400UK ($250–$270): SL401 wins on US market availability and feature refinements, SL400UK wins on lower price for near-identical stacked dual-zone performance
vs Ninja Foodi DZ550 10 Qt ($200–$250): SL401 wins on compact vertical footprint for small kitchens, DZ550 wins on wider basket surface for more even crisping without frequent shaking
vs Ninja Foodi DualZone XL DZ401 ($180–$200): SL401 wins on total capacity in smaller counter space, DZ401 wins on price and wider basket geometry for better airflow and even cooking
vs Ninja DZ201 Foodi 8 Qt ($180–$220): SL401 wins on capacity and dual-zone cooking in tighter spaces, DZ201 wins on lower price and proven even cooking in wider basket format

AI-summarized review themes

Frequently Praised

Compact stacked footprint fits under cabinets and frees counter space versus side-by-side models
Cooks four foods simultaneously using racks and baskets for complete family meals
Baskets and racks are dishwasher-safe and wipe clean without stuck-on residue

Frequently Criticized

Rear heating causes uneven front-to-back cooking, requiring mid-cook shaking or rotation
Fan is noticeably louder than typical air fryers, disruptive in open kitchens
Cook times run longer than expected, particularly when using both levels simultaneously

Best for

families of 4+ in small kitchens, cooking multiple items simultaneously, replacing oven for daily meals

Not for

people wanting set-it-and-forget-it even cooking, quiet operation in apartments, singles wanting compact single-basket

Specifications

Spec	Value
Cooking Capacity	10 QT (2 x 5 QT baskets)
Cooking Functions	Air Fry, Air Broil, Roast, Bake, Reheat, Dehydrate
Wattage	1690 W
Dimensions (L x W x H)	20.83” x 13.07” x 17.72”
Weight	25.13 lbs
Dishwasher Safe Parts	Baskets, crisper plates, racks
Smart Features	Smart Finish, Match Cook
Included Accessories	2 crisper plates, 2 stacked meal racks

Data sources

Estimated ~82 purchase reviews via Best Buy
Estimated ~146 purchase reviews via Target
Estimated ~74 purchase reviews via Walmart
Review period: Apr 2025 - Apr 2026
Sentiment confidence: high

Ninja Double Stack XL SL401 Air Fryer (SL401)