A 6000-mAh power bank runs 3–6 hours of continuous 5W draw or gives 1–2 full phone charges, based on 60–80% efficiency.
You bought a compact charger and want to know what sort of run time to expect. A six-thousand-milliamp-hour pack can usually refill a modern phone once, maybe twice, and can keep a low-power gadget going for a few hours. The exact result swings with charging speed, cable losses, and how your device sips power while it’s topping up.
How the math works is simple. Power banks are rated at the cell’s native voltage, near 3.7V. Phones and small gadgets charge over USB at around 5V or higher, so a boost converter inside the pack steps the voltage up and wastes some energy as heat. In day-to-day use you get about sixty to eighty percent of the label. That puts usable capacity for a six-thousand pack near 3600–4800 mAh at 3.7V, which translates to roughly 13–18 Wh.
To turn that into charges, divide usable watt-hours by your device’s battery watt-hours. If your phone holds 12 Wh, you’ll see one full refill and a little change. If it holds 18 Wh, expect about a half to one charge. Tablets and handheld consoles draw more, so the same pack gives partial top-ups or a few hours of play.
Quick Reference: Expected Full Charges
This table uses a mid-range efficiency of about seventy percent. If your cable and pack are top tier, you may land near the upper bound; older cables or cheap adapters push you toward the lower bound.
| Device Type | Typical Battery | Estimated Full Charges |
|---|---|---|
| Small Phone | 10–12 Wh | 1.1–1.5 |
| Large Phone | 14–16 Wh | 0.8–1.2 |
| Compact Tablet | 18–20 Wh | 0.6–0.9 |
| Full-size Tablet | 25–30 Wh | 0.4–0.7 |
| Handheld Console | 12–16 Wh | 0.8–1.2 |
| Smartwatch Case | 1–2 Wh | 6–12 |
How Long A 6000mAh Bank Runs In Real Life
Think in hours and charges, not just the label. At a gentle 5W load—something like a phone trickle or a Bluetooth speaker—a six-thousand pack can hold a device alive for three to six hours straight. At 10W, expect closer to two to three hours. Push 15W or 20W fast charging and the same energy drains faster, so the window tightens. The pack doesn’t lose energy because you charge faster; you just spend the same budget in less time.
Charging a phone from twenty percent to full pulls less energy than zero to full, and phones taper current near the top, which helps stretch a small pack. Screen-on charging burns extra watt-hours. If you’re watching video while plugged in, part of the output feeds the screen and radios instead of the battery cell, which shortens the number of “fulls” you can log.
Simple Formula You Can Reuse
Here is the quick way to estimate. Convert the pack’s rating to watt-hours, apply an efficiency range, then divide by your device’s battery size.
Step 1: Convert To Watt-Hours
Multiply the label in mAh by 3.7 and divide by 1000. A six-thousand pack is about 22.2 Wh before losses.
Step 2: Apply Real-World Efficiency
Use sixty to eighty percent for a quality brand and a decent cable. That places usable energy near 13–18 Wh.
Step 3: Divide By Your Device
Look up your gadget’s battery watt-hours. Divide usable Wh by that number to get how many full refills you can expect, or divide usable Wh by your device’s typical power draw in watts to estimate hours of continuous use.
What Changes The Outcome
Charging Speed And Protocols
Higher power modes shorten clock time but not energy use. A 20W burst looks fast yet still spends the same watt-hours as a slower 10W session. Mismatch between charger and phone can drop efficiency; if your phone falls back to basic 5V modes, the conversion circuit often runs a little cooler and wastes less.
Cables And Adapters
Thin or damaged leads can drop voltage under load and waste power as heat. Use short, certified cables for best results. If you insert a cheap adapter or dongle in the path, you stack losses.
Ambient Temperature
Lithium cells deliver less energy in cold weather and age faster in heat. Keep the pack out of direct sun and don’t leave it in a freezing car. Mid-room temps keep both capacity and lifespan healthier.
Device Behavior While Charging
Background tasks, GPS, and high brightness eat into the budget. Airplane mode or a brief screen-off break during charging can net an extra chunk of energy into the battery cell instead of the workload.
Worked Scenarios
Modern Phone, Light Use
Say your phone carries a 12 Wh battery. Usable energy from the six-thousand pack sits near 15 Wh with a good cable. From ten percent to one-hundred percent you need about 10.8 Wh. That’s one clean refill with headroom for a top-up later in the day.
Big-Screen Phone, Heavy Use
A larger handset at 15 Wh that you keep bright and online can eat nearly the whole bank in one go. You’ll still reach full from a low level, but little remains.
Compact Tablet Catch-Up
A small slate at 19 Wh will climb about half to two-thirds on a single tether. That’s enough to finish a movie on a flight or push through a meeting without hunting for a wall socket.
Handheld Console Session
A console that draws 7–10W while gaming can gain two to three extra hours from this pack. If the title is demanding and the screen is bright, the boost leans closer to the low end.
Why Your Mileage Varies
Two things drive the gap between the label and what reaches your device: voltage conversion and phone-side charging losses. A pack stores energy near 3.7V but outputs 5V or higher over USB, which adds conversion loss in the boost circuit. Anker’s efficiency note lays out the typical sixty to seventy percent usable window. Your device also sheds a slice inside its charge controller and cable. That’s why two phones with the same size battery can report different results from the same pack.
Run Time By Load
These hour ranges use a mid-pack usable energy of 15 Wh. More efficient gear pushes them up a bit; cold weather or screen-on use pushes them down.
| Load (Watts) | Estimated Hours | Typical Use |
|---|---|---|
| 3W | 4–6 | Small speaker, basic phone idle |
| 5W | 3–4 | Phone trickle, e-reader, hotspot idle |
| 7.5W | 2–3 | Phone screen on, light gaming |
| 10W | 1.5–2 | Tablet standby, heavier phone use |
| 15W | 1–1.5 | Fast phone charge while screen off |
| 20W | 0.7–1 | High-power burst charging |
Quick Calculator Walkthrough
Run two tiny checks you can copy for any gadget. First, say your earbuds case holds 1.5 Wh. With 15 Wh usable in the pack, that’s 10 full case charges. Second, say your handheld pulls 8W while you play. With 15 Wh usable, divide by 8 for around two hours of extra game time. Swap your own numbers and you’ll get a close estimate in seconds.
Charging Speed Myths
Fast modes don’t “waste” the bank by magic. What matters is watt-hours in and out. Faster sessions raise current, the converter warms up a bit, and you may land a few percent lower than a slow 5V charge. The time savings often outweigh that small tradeoff, especially when you only need to climb from forty to eighty percent before heading out the door.
One more point: a low pack charges a phone less efficiently than a half-full one. As the cell nears empty, the converter works harder to hold voltage, and losses climb. If you want every drop, stop short of zero and refill the pack when you can.
Source Notes
The efficiency band used here reflects guidance from a major charger maker. See Anker on varying delivered energy for a clear walkthrough. Device spec pages often list energy in watt-hours; a handy reference is the iPad technical specifications, which present battery energy in Wh, matching the math used above.
Safety And Care
Use quality cables and skip no-name adapters. Don’t cover the pack while it’s working hard; a little airflow helps. Store around half charge if you won’t use it for a month. If the shell bulges or the pack runs hot at light loads, recycle it at an e-waste drop-off and replace it.