Sabja
Heat permanently wears down a battery. Sabja is an iPhone heat monitor that reads Apple’s Thermal State, which rises when heavy apps, charging, or a hot room put your iPhone under thermal pressure, and tells you when a short break will help, so your iPhone keeps more of its battery health, its speed, and its value when you upgrade.
Apple’s own Thermal State
No account needed
Monitoring works offline
Anyone can see Maximum Capacity in Settings › Battery › Battery Health, including the buyer or trade-in partner pricing your phone.
When I went to exchange my iPhone 12 mini, it was valued at ₹24,600. Its battery’s Maximum Capacity had dropped below 85%, so the offer came in ₹7,400 lower.
Around the same time, my brother nearly had to replace his iPhone 13 after its battery swelled.
Heat is one of the things that wears a battery down faster, and iOS rarely tells you when it’s happening. I built Sabja so you notice it early and look after your iPhone’s battery while it still counts.
A warm iPhone protects itself by slowing down. The bigger cost is the part you can’t see: battery capacity that never comes back.
When an iPhone runs past its normal operating range, Apple says you might notice:
These changes are permanent. Every hot hour adds to the battery’s chemical age.
A hotter year can cost about 15 more points of capacity. In Battery University’s estimates, a lithium-ion battery stored fully charged for one year keeps about 80% of its capacity at 25 °C, but only about 65% at 40 °C.Lab storage estimates for cobalt-based lithium-ion cells, not iPhone measurements. Source: BU-808 ↗
Fewer hot hours mean slower capacity loss, so a full charge keeps covering your day for longer.
Easing off at Fair helps you avoid the frame-rate drops and camera cut-outs that iOS applies when thermal pressure rises.
A cooler iPhone is less likely to have charging slowed or paused, so you leave with the charge you expected.
A battery that holds its capacity is one less reason for a buyer to cut the price.
The app and its widgets check in through the day, using the same signal iOS uses to manage thermal pressure.
A calm alert arrives when Thermal State reaches Fair, Serious, or Critical, and again when it eases.
Pause heavy apps, or unplug and take off the case for a few minutes. That’s usually enough.
Sabja doesn’t cool your iPhone. It tells you when a short break can help.
Sabja keeps a record of when your devices run warm, so the patterns that wear your battery down become easy to spot and easy to change.
Warm Time compares today and this week with what’s usual for you. Time of Day shows when your warm time peaks, so you can save heavy tasks for cooler hours.
Weekly Match compares this week’s warm time with last week at the same point. Pick a target, follow the Live Match, and build a record of cooler weeks.
See how many of your charges got warm, how soon they warm up, and how often you charge below 20% or above 90%. The 40–90 guide helps you spend less time near empty and near full.
Turn on Share Thermal State and see your iPhone, iPad, Mac, and Apple Watch together in the app and in the All Devices widget. It syncs through your private iCloud, which only your devices can read.
Lock Screen widgets keep checking Thermal State when Sabja isn’t open, and the Weekly Match widget shows how this week compares with last week. Tap a widget to refresh it.
One device monitor for iPhone, iPad, Mac, and Apple Watch, with a single purchase.
Thermal State lives in your menu bar. With Sabja Pro, Active Now shows what’s keeping your Mac busy, from CPU and GPU to memory, disk, and network, with one thing to try and a shortcut to Activity Monitor.
Home, History, Matches, and Charging, laid out for the bigger screen.
Your watch’s own Thermal State at a glance, with a complication for your watch face.
A phone temperature checker that shows degrees is guessing: iOS doesn’t let apps read the exact temperature of your battery or processor. Sabja reads the Thermal State iOS itself uses to manage thermal pressure: Nominal, Fair, Serious, or Critical.
Core monitoring runs on your device and works offline. No account, no sign-up.
Everything you need to check your device right now.
The habits that protect your battery over months.
Practical, sourced guides to what causes heat, what’s normal, and what to do next.
New Apple devicesWhy battery care and thermal awareness belong in your day-one setup.
BatteryWhat heat does to capacity, and the habits that matter most.
CoolingSix safe steps, and the shortcuts to avoid.
Your battery only gets one life
Download Sabja free for iPhone, iPad, Mac, and Apple Watch. Check your Thermal State today, and unlock alerts, History, Matches, Charging, and widgets with Sabja Pro.
Download on theApp Store
Scan to downloadFree on the App Store