LG K51 Review

We purchased the LG K51 so our expert reviewer could thoroughly test and assess it. Keep reading for our full product review.

The LG K51 is a budget smartphone that originally launched as a Boost Mobile exclusive, but it’s available from a number of carriers and also in an unlocked version that you can take anywhere. The best thing about this phone is the very affordable price, but it also boasts a pretty big battery, a three camera array on the rear, and a 13MP front-facing selfie cam, among some other intriguing features.

I recently replaced my personal phone with an LG K51 for about a week to see whether the less-than-impressive MediaTek Helio processor has too much of an effect on performance. I also tested the camera, speakers, screen, and other aspects of this phone to see how many corners LG had to cut to hit such a great price point in a phone that looks this good.

Design: Attractive glass sandwich form factor looks and feels premium

The LG K51 is a pretty standard glass sandwich design, with chunky bezels and an attractive camera teardrop on front, and a three camera array, thumbprint sensor, and LG logo around back. It’s available in a single color that LG refers to as titan, but it’s just black. It lacks the flashy iridescence of something like the LG Stylo 6, but the understated glass sandwich design looks and feels far more premium than you’d expect from a phone with such a low price tag.

This is a pretty big phone, and it has a large screen to match. The display measures 6.5-inches, and it dominates the front of the handset. The top and bottom bezels are exceptionally thick, including a pleasantly curved camera teardrop up top, while the side bezels are a bit thinner. The screen is big enough that, despite having fairly big hands, it was a bit tough to reach every bit of the display with my thumb without moving the phone significantly around in my grip.

The aforementioned three camera array is arranged horizontally over the thumbprint sensor on a glass back that acts as a major fingerprint magnet. Like other three camera arrays, you get one sensor dedicated to traditional photos, one for wide angle shots, and another for sensing depth and applying bokeh effects. The thumbprint sensor is small and slightly textured to make it easy to find.

The right side of the frame features a SIM card drawer and the power button, while the volume switch and a dedicated Google Assistant button are found on the left side. The bottom of the phone has three holes for one of the speakers, a USB-C port that supports fast charging, and a 3.5mm headphone jack.

Display Quality: Low resolution screen falters on close inspection

The LG K51 features a huge 6.5-inch IPS LCD display that looks great at a distance, but not as great on closer inspection. The resolution is just 1560x720, which puts the pixel density at 264ppi. It isn’t like this resolution is going to hurt your eyes or anything, but it’s significantly lower than even other budget-priced phones.

The screen itself has decent color reproduction, although the colors felt a bit on the cold side. It also has great viewing angles with no real color distortion or any other issues. I’d have preferred to see a display more in line with the 2460x1080 IPS LCD found in the Stylo 6, but this is clearly one area where LG cut some corners to hit a lower price point.

Performance: Works okay in practice, but lags behind the competition

The K51 features a MediaTek Helio P22 2.0GHz Octa-Core that’s just not up to the standards of hardware I’ve tested in other budget-priced phones. That assessment was confirmed when I ran some benchmarks, starting with the Work 2.0 benchmark from PCMark. It scored just 3,879 in that benchmark, with scores of 3,879 in web browsing, 3,302 in writing, and 5,469 in photo editing.

The K51’s Work 2.0 benchmark scores slightly edge out another budget LG phone, the Stylo 6, but that doesn’t mean they’re good. For example, the slightly more expensive Moto G Power boasts an overall score of 6,882. My trusty old Pixel 3, a flagship phone from three years ago, hits 8,808 as an additional point of comparison.

In addition to the productivity-centric Work 2.0 benchmark, I also installed GFXBench and ran some gaming benchmarks. First up, I ran the Car Chase benchmark that’s meant to simulate a fast-paced 3D game with advanced effects. The LG K51 crashed and burned hard, managing just 4.4 frames per second (fps) on that benchmark.

After Car Chase, I ran the T-Rex benchmark. This is a less intense 3D gaming benchmark, and the K51 managed to record a more acceptable 27fps. That’s not too bad, and suggests you should be able to actually do some light gaming on this phone if you stick to less demanding apps.

In daily use, the LG K51 didn’t give me too many issues. It isn’t as responsive as the Pixel 3 I’m still clinging to and use whenever I’m not testing a new phone, but it wasn’t quite as bad as I expected considering the hardware. I noticed some hesitation when launching apps, switching screens, and bringing up elements like the onscreen keyboard from time to time. Overall, performed basic tasks like email, web browsing, and streaming video perfectly fine.

I also loaded up some games, including Asphalt 9, to see how the K51 actually runs a game. Asphalt is pretty well optimized, and it actually ran fairly well. It didn’t look as good as it does on better hardware, and I did notice a few frame drops, but it worked better than I expected.

Somewhat tied to performance is the onboard storage, or really the lack thereof. The K51 only has 32GB of built-in storage, 13GB of which is taken up by system files. By the time I installed my benchmarks and a few necessary apps, the phone only had 12GB of free space. This is a really small amount of storage, even for a phone of this price, so plan on investing in a decent SD card if you want to install more than a few apps or take any pictures or video.

Connectivity: Surprising LTE performance and good Wi-Fi speeds

The LG K51 is available in a few different variations for different carriers, and each one supports a slightly different set of LTE bands. In addition to a variety of LTE bands, it also supports Bluetooth 5.0, 802.11ac dual-band Wi-Fi, Wi-Fi Direct, and can work as a hotspot if your carrier supports that.

For testing purposes, I connected the LG K51 to Google Fi using T-Mobile towers. I was impressed with its LTE performance overall, managing download speeds of 20Mbps in an area where my Pixel 3 only managed 15Mbps. Another budget LG smartphone, the Stylo 6, only hit a top download speed of 7.8Mbps at the same time and in the same location. In all of the areas where I used the LG K51, it performed strongly compared to my other test phones.

The K51 also turned in decent results in my Wi-Fi tests. Using a 1Gbps Mediacom cable internet connection and an Eero mesh Wi-Fi system, I tested the K51 near the router, then at a handful of intervals at varying distances from the router and beacons.

Tested near the router, the K51 managed a top download speed of 227Mbps. In the same location, my Pixel 3 hit a slightly faster speed of 320Mbps. The K52 dropped slightly to 191Mbps at a distance of 30 feet with some obstructions, 90Mbps at 50 feet and significant obstructions, and then held strong at an impressive 84Mbps at a distance of about 100 feet down in my garage.

Sound Quality: Loud and surprisingly clear

LG is known for putting pretty great speakers in their high-end phones. The K51 doesn’t exactly have premium speakers, but this phone sounds better than most budget handsets I’ve tested. It’s loud, plenty loud enough to fill a room, and there’s very little distortion even at the highest volume. Everything comes through loud and clear to a degree that’s actually pretty impressive for a phone in this price range.

To test the sound quality on the K51, I loaded up the YouTube Music app and queued up the Pentatonix cover of “Radioactive” that features strings by Lindsay Stirling. The vocal-heavy track sounded far better than I expected, with bright, clear strings and almost no distortion. The YouTube Music algorithm threw on Pentatonix’s Daft Punk supermix after that, and it sounded even better.

The one real issue with the sound is that it’s really easy to block the three small speaker holes on the bottom edge of the phone. Block those, and the sound becomes muffled, quiet, and difficult to understand.

Camera/Video Quality: Takes decent pictures, but video quality isn’t that great

The LG K51 features a three sensor array on the back for taking regular photos and wide-angle photos, and another camera on the front for videoconferencing and selfies. The main sensors on both the front and back are 13MP, while the back also includes a 5MP ultrawide camera and a 2MP depth sensor.

The rear camera takes decent pictures provided decent light is available. I was fairly impressed with the level of detail and color in outdoors shots in particular, both close-up and medium range. Wide angle shots lose some detail, but they turned out okay as well. That quality takes a sharp turn in less than perfect light though, with significant levels of noise creeping in.

The front-facing selfie cam also works quite well in good light, producing high quality stills that get a bit muddy and noisy in lower light.

I wasn’t as impressed with video from either the rear or front camera. The rear camera does okay in good lighting, although I noticed a bit too much motion blur and difficulty focusing. In low light, I saw a whole lot of noise that bordered on distortion in some cases.

The front camera is good enough for videoconferencing and video apps if you position it right and have decent lighting. You may end up wanting to invest in a ring light, as my results with just natural and regular in-room lighting resulted in a pretty mixed bag. Both front and rear cameras max out at 1920x1080 for recording video.

Battery: Tons of capacity for great battery life

The LG K51 features a big 4,000 mAh battery, which is good because a screen this big takes a lot of juice to power. Even with the big display, the battery life of the phone was quite decent. I was able to go about two days at a time without a charge, using the phone for calls, texting, and some light web browsing and email.

To get an idea of the exact limits of the LG K51’s battery, I set the screen brightness to full, connected to Wi-Fi, and streamed YouTube videos non-stop until the phone died. Under those conditions, the battery lasted nearly 12.5 hours. That isn’t quite as long as some budget phones I’ve had my hands on, but it’s pretty good for a phone in this price range.

Software: LG’s take on Android fails to impress

The K51 ships with either Android 10 or Android 9 depending on the carrier you get the phone from. My test unit was unlocked, and it came with Android 10. That’s good, but the issue is that the K51, like other LG phones, doesn’t exactly run stock Android. It uses LG’s own LG UX 9.0, which I’m not a huge fan of. 

The biggest change from stock Android 10 to LG UX 9.0 is that LG got rid of the app drawer for some reason. Instead, you’ll find all of your apps spilled out across pages and pages of desktop. That probably works for some people, but it feels messy and unorganized to me. You can turn back an approximation of the app drawer in the settings, or just use a custom launcher if you prefer.

The K51 comes with a handful of pre-installed apps primarily for productivity that you may or may not find useful. I have my own old stand-bys that are easily available in the Play Store, and I was able to install them pretty fast. The only issue is that on a device with such a small amount of storage, you may end up needing to remove LG’s included apps to make room for your own.

Price: Tough to beat

The best thing about the LG K51 is undoubtedly the price. With an MSRP of $200 unlocked, and often available for less than half of that if you buy from a carrier, this phone represents a pretty good deal under the right circumstances. The slow processor makes it a bit of a tough sell at MSRP, as you can get a significantly better phone for about $50 more, but if you’re working with a hard limit of $200 this phone has a whole lot going for it.

LG K51 vs. Moto G Power

The Moto G Power is a budget smartphone that sells for a bit more than the K51, with an MSRP of $250. It’s a smaller phone, with a 6.4-inch display and a significantly smaller body, but it blows the K51 out of the water in almost every respect. Its Work 2.0 benchmark is nearly two times higher than the K51, and its 5,000 mAh battery lasts nearly four more hours when tested under the same conditions. It also has a higher resolution display, twice the built-in storage, and better cameras.

The LG K51 is still worth looking at if you can’t afford something like the Moto G Power, or if you find it on sale, but there’s no question here as to which one is a better value for the money. The Moto G Power runs circles around the LG K51 in every category.

Similar Products We've Reviewed:

• LG Stylo 4
• LG K30
• LG V40 ThinQ