The kitchen is often a game of inches. Between the coffee maker, the stand mixer, and the inevitable pile of mail, the countertop is precious real estate. This is why the Ninja “Flip” series – ovens that literally stand up and out of the way – has become a cult favorite for anyone living in a condo or a home with limited prep space. But recently, Ninja expanded the lineup, moving from the classic Ninja SP151 (Digital Air Fry Oven) to the high-tech Ninja SP351 (Foodi Smart Dual Heat Air Fry Oven).
After putting both through a rigorous “real-world” testing phase – which involved everything from reheating cold pizza to searing high-end ribeyes – I’ve realized that while they share a similar silhouette, they belong in different kitchens. One is an incredible speed-demon for snacks and quick bakes, while the other is a precision-engineered tool designed to replace several of your stovetop pans. If you’re struggling to decide if the “Smart” features of the SP351 justify the higher price tag, here is my honest take on which one actually deserves that spot on your counter.
The Key Difference: Ninja SP151 vs. SP351 Air Fryer Toaster Oven Combo
The fundamental evolution between the SP151 and the SP351 is all about how the heat hits your food.
- The Ninja SP151 relies on OvenCrisp Technology. It uses six infrared heating elements and a high-speed fan to circulate air. It’s essentially a very fast, very efficient air fryer and toaster.
- The Ninja SP351 introduces Dual Heat Technology. It features a specialized, directly heated SearPlate that reaches 500F. This allows the oven to cook with “contact heat” (like a skillet) and “cyclonic air” (like an air fryer) simultaneously. It also adds an Integrated Smart Thermometer to monitor internal temperatures in real-time.
Comparison Table: Ninja SP351 vs. Ninja SP151 Air Fryer Toaster Oven Combo
| Feature | Ninja SP351 (Smart Dual Heat) | Ninja SP151 (8-in-1 Digital) |
| Cooking Technology | Dual Heat (SearPlate + Air) | OvenCrisp (Infrared + Air) |
| Smart Features | Integrated Smart Thermometer | None (Manual Monitoring) |
| Max Temp | 500F | 450F |
| Internal Height | XL Capacity (Fits a 2-lb Roast) | Standard (Fits 6 Chicken Breasts) |
| Functions | 13-in-1 (Griddle, Sear Crisp, etc.) | 8-in-1 (Air Fry, Roast, Pizza, etc.) |
| Wattage | 1800 Watts | 1800 Watts |
| Storage Style | Flip Up & Away | Flip Up & Away |
| Preheat Time | Ready in 60 Seconds | Ready in 60 Seconds |
| Cooking Speed | Up to 65% faster vs. full oven | Up to 50% faster vs. full oven |
| External Depth | 20.21″ | 17.01″ |
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My Take: A Detailed Comparative Review
Design: The Footprint of Innovation
Visually, both ovens are stunning. They feature that brushed stainless steel look that makes them feel like professional kitchen tools. When I flipped the SP151 up against my backsplash, I was amazed at how much room it saved – it’s only about 7.5 inches tall when folded. It’s the perfect size for someone who just wants the oven “gone” when it’s not in use.
The SP351 is slightly deeper and taller. When it’s down in the cooking position, it takes up a bit more of the counter. However, that extra internal height is a massive win. One of the frustrations I had with the older model was that I couldn’t cook anything “thick.” If I put a bagel on the rack, it was inches away from the elements. The SP351 feels roomier inside; I was actually able to air-roast a 2-lb pork loin without worrying about the top scorching.
Ease of Use: The “Set and Forget” Factor
The SP151 is incredibly straightforward. You turn the dial to “Air Fry,” set your temp, and hit start. It’s fast and predictable. However, I found myself constantly setting a separate timer on my phone or hovering over the glass with a handheld thermometer whenever I cooked meat. It requires your full attention if you want perfect results.
The SP351 takes all that anxiety away with the Foodi Smart Thermometer. I poked the probe into a thick salmon fillet, selected “Medium” on the display, and went to check my email. The oven precisely monitored the internal temperature and beeped the second it reached the target. This level of automation is something I didn’t know I needed until I had it. It turns a toaster oven into a “smart” sous-chef.
Functions: Searing Crust vs. Air Fried Crunch
If you primarily eat frozen fries, chicken nuggets, or toast, the SP151 is a champion. Its air fry function is top-tier, producing a crunch that is 75% less fatty than deep frying. It’s a specialized tool that does its job exceptionally well.
However, the SP351 is a more versatile culinary machine. Because of the SearPlate, I was able to use the “Griddle” function to make breakfast sausages and eggs directly in the oven. The “Sear Crisp” mode is the real standout – it gives chicken thighs a crispy, golden skin while the bottom sears against the 500F plate. It’s the first countertop oven I’ve used that can actually produce a “cast-iron” style crust on a steak.
Maintenance: The Cleanup Comparison
Both units feature a “Flip Away” design that makes cleaning the bottom of the oven a breeze. You just flip it up and wipe the crumb tray.
The SP351’s SearPlate is a heavy-duty, non-stick pan that I found surprisingly easy to clean. Even after searing greasy burgers, the residue wiped off with minimal effort. The SP151’s sheet pan is also good, but it’s thinner and more prone to warping over time if you use it at high temperatures frequently. One thing to note: because the SP351 gets hotter 500F, you do have to be more diligent about wiping the internal walls to prevent grease build-up from smoking during the next use.
Ninja SP351 (Smart Dual Heat) Air Fryer Toaster Oven Combo
Pros:
- Dual Heat Power: Searing capability that rivals a stovetop skillet.
- Integrated Probe: No more overcooked or undercooked meat.
- Roomy Interior: More vertical space for thicker foods and small roasts.
- 13 Functions: The most versatile “flip” oven on the market.
Cons:
- Depth: It sticks out a few inches further on the counter than the SP151.
- Cost: It is a premium investment for the added technology.
Ninja SP151 (Digital 8-in-1) Air Fryer Toaster Oven Combo
Pros:
- Ultra-Compact: Takes up the absolute minimum amount of space.
- Efficient: 80% more energy efficient than a full-size oven.
- Fast: Preheats in 60 seconds and cooks 50% faster than traditional ovens.
- Value: Offers the best “bang for your buck” for air frying and toasting.
Cons:
- Low Clearance: Not suitable for taller foods or thicker cuts of meat.
- Basic Tech: Lacks the searing plate and the smart thermometer.
Verdict: Which One Should You Buy?
Both of these ovens are fantastic for reclaiming your kitchen workspace, but the “best” one depends on your cooking habits.
I recommend the Ninja SP151 if:
You are a “toast and snacks” cook. If you want a fast, reliable machine for air frying wings, baking 12-inch pizzas, and making the best toast of your life, the SP151 is a perfect fit. It’s smaller, more affordable, and handles the basics with incredible speed.
I recommend the Ninja SP351 if:
You are a “meals and proteins” cook. If you want to roast salmon, sear steaks, or cook whole meals for a family of four, the Dual Heat technology and the Smart Thermometer are game-changers. The extra internal height makes it feel like a true replacement for your big oven rather than just a high-end toaster.
My Personal Recommendation: I found that the Ninja SP351 completely changed how I meal prep. Being able to sear and air-fry a chicken breast at the same time while a thermometer ensures it stays juicy is a level of convenience I can’t live without. It is the definitive “Pro” version of the flip-oven concept.
Frequently Asked Questions
Does the SP351 really cook faster than the SP151?
Yes, but only slightly. The SP351 is rated up to 65% faster than a full oven, whereas the SP151 is 50% faster. The real speed difference comes in the “Dual Heat” functions where the SearPlate accelerates the cooking of the bottom of the food.
Can I fit a 9×13 pan in these?
No. Both ovens are designed for a 13×13 sheet pan. A standard 9×13 pan with handles is usually too wide to fit comfortably inside the “Flip” series ovens.
Is the thermometer in the SP351 accurate?
In my side-by-side tests with a professional-grade Thermapen, the Foodi Smart Thermometer was within 2 degrees of accuracy. It is highly reliable for everyday kitchen use.
Can I leave the oven flipped up while it’s still hot?
No. Ninja recommends letting the oven cool for at least 10 minutes before flipping it up. This prevents heat damage to your backsplash and ensures the crumb tray doesn’t spill hot grease.
Is the SP351 worth the extra money?
If you cook raw meat (steak, chicken, fish) at least three times a week, yes. The thermometer alone prevents enough “ruined dinners” to pay for itself over time. If you only use it for toast and frozen pizza, the SP151 is the better value.
