Samsung Galaxy Z Fold 8, Fold 8 Ultra, and Flip 8 battery life tested — silicon carbon pays off

(Image credit: Tom's Guide) As much as I rave about the extra utility that the best foldable phones have over traditional slabs, there’s one unspoken compromise they make: subpar battery life. Even though I personally don't mind topping off at some point during the workday, doing so can be a deal breaker for anyone who craves all-day endurance.With the launch of Samsung’s new foldables, they certainly have a lot to prove — more so when they’re also some of the thinnest and lightest models to date. The Galaxy Z Flip 8, Z Fold 8, and Z Fold 8 Ultra are notable as the first Samsung devices to adopt silicon-carbon batteries, which pack more capacity without adding extra bulk.Paired with the power-efficient Snapdragon 8 Elite Gen 5 silicon, they’re bound to be some of the longest-lasting foldables to pass through the Tom’s Guide labs. After putting them through a barrage of battery drain tests, I can tell you they don’t disappoint.Galaxy Z Fold 8 vs Fold 8 Ultra vs Flip 8: Battery life results Swipe to scroll horizontally Row 0 - Cell 0 Battery Capacity (mAh) Battery Life (hrs:mins) Galaxy Z Flip 8 4,300 mAh 12:50 Galaxy Z Flip 7 4,300 mAh 12:24 Razr Ultra (2026) 5,000 mAh 16:20 Interestingly, the Z Flip 8’s battery life performance doesn’t seem as dramatic as the other phones — especially considering it packs the same 4,300 mAh capacity as before. What’s different this time is how Samsung engineered the phone to be thinner and lighter than its predecessor without compromising on battery capacity.The new flip-style phone clocks in at 12 hours and 50 minutes, representing a 3.5% increase over the Flip 7’s 12:24 runtime. Against its biggest rival, the Razr Ultra (2026), Motorola still holds the title of the longest-lasting flip phone with a time of 16 hours and 20 minutes. That’s a huge gap, primarily aided by Motorola's massive 5,000 mAh battery. Swipe to scroll horizontally Row 0 - Cell 0 Battery Capacity (mAh) Battery Life (hrs:mins) Galaxy Z Fold 8 4,800 mAh 12:20 Galaxy Z Fold 8 Ultra 5,000 mAh 14:09 Galaxy Z Fold 7 4,400 mAh 10:44 Razr Fold 6,000 mAh 14:44 Pixel 10 Pro Fold 5,015 mAh 12:16 Despite this, where Samsung truly makes a massive leap is in its flagship book-style foldables. The premier Galaxy Z Fold 8 Ultra logs an extraordinary 14 hours and 9 minutes, blowing past the Z Fold 7’s 10 hours and 44 minutes. That’s an impressive 31.8% increase in endurance. Likewise, the Galaxy Z Fold 8 also sees a substantial gain at 12 hours and 20 minutes — a 14.8% improvement compared to last year's Fold 7.Against its key rivals, the Z Fold 8 Ultra proves it can hold its ground with the best in the business. Clocking in at 14 hours and 9 minutes, Samsung's premium foldable comfortably outperforms the Google Pixel 10 Pro Fold by a margin of 15.3%.Get instant access to breaking news, the hottest reviews, great deals and helpful tips.Galaxy Z Fold 8 vs Fold 8 Ultra vs Flip 8: Charging speeds Swipe to scroll horizontally Row 0 - Cell 0 Charging Speed (in 15 minutes) Charging Speed (in 30 minutes) Galaxy Z Fold 8 43% 70% Galaxy Z Fold 8 Ultra 49% 76% Galaxy Z Fold 7 28% 54% Razr Fold 41% 73% Pixel 10 Pro Fold 28% 58% Charging is another area where Samsung’s new phones make noticeable gains — specifically with a bump to 45W wired charging across all three models. That’s a welcome increase from the previous 25W cap, allowing them to juice up much faster in the same timeframe.The Galaxy Z Fold 8 Ultra leads the pack, hitting 49% in 15 minutes and 76% in 30 minutes. That’s an impressive leap over the Z Fold 7’s 54% mark, even outstripping the Motorola Razr Fold’s 73%. The standard Z Fold 8 also impresses by reaching 70% in half an hour. Swipe to scroll horizontally Row 0 - Cell 0 Charging Speed (in 15 minutes) Charging Speed (in 30 minutes) Galaxy Z Flip 8 35% 59% Galaxy Z Flip 7 29% 55% Razr Ultra (2026) 42% 74% Meanwhile, the Z Flip 8 offers a slighter improvement over its predecessor, reaching 59% in 30 minutes compared to the Flip 7’s 55% — a surprisingly modest gain given the wattage upgrade. While that still trails the Motorola Razr Ultra’s blazing 74% charge result, Samsung’s entire 2026 lineup comfortably outpaces rivals like the Google Pixel 10 Pro Fold (58%), ensuring less time tethered to a wall adapter.Galaxy Z Fold 8 vs Fold 8 Ultra vs Flip 8: Verdict (Image credit: Tom's Guide)If you weren’t convinced already, I’ll state it again: silicon-carbon batteries are making a massive impact — and Samsung’s new foldables cement my sentiment. Foldable phones have come a long way, and battery performance is no longer one of their compromises.By introducing silicon-carbon battery technology alongside 45W wired charging, Samsung’s 2026 Galaxy Z lineup delivers meaningful upgrades where it matters most and makes them solid best phone battery life contenders. These improvements should translate to tangible real-world gains, powering you through a full workday without the constant need to top off.While Motorola continues to push the upper boundaries of battery life with its Razr series, Samsung’s Galaxy Z Fold 8 Ultra stands out as the ultimate powerhouse, comfortably outlasting rivals like the Pixel 10 Pro Fold while charging faster than ever before. Whether you prefer a compact flip or an immersive book-style screen, you can finally enjoy foldable productivity without constantly watching your battery level. Follow Tom's Guide on Google News and add us as a preferred source to get our up-to-date news, analysis, and reviews in your feeds. More from Tom's GuideI just spent 24 hours with the Galaxy Z fold 8 Ultra — here's what I liked and what I didn't‘We're pretty confident': How Samsung plans to fight the first foldable iPhoneI just ditched my iPhone for the Z Fold 8 — Android 17’s new migration tool is pure magic, but there is one painful catch John’s a senior editor covering phones for Tom’s Guide. He’s no stranger in this area having covered mobile phones and gadgets since 2008 when he started his career. On top of his editor duties, he’s a seasoned videographer being in front and behind the camera producing YouTube videos. Previously, he held editor roles with PhoneArena, Android Authority, Digital Trends, and SPY. Outside of tech, he enjoys producing mini documentaries and fun social clips for small businesses, enjoying the beach life at the Jersey Shore, and recently becoming a first time homeowner.