A 10,000mAh power bank gives about 1.5–2.5 phone charges, based on battery size and 70–85% efficiency.
Here’s the short, practical answer up front. A 10,000mAh pack holds roughly 37Wh of energy at the cell level (most cells sit near 3.7V). After conversion losses, cables, and heat, you can usually tap 26–31Wh. That translates to one to two full phone charges for larger batteries and closer to two or more for compact phones. The exact count depends on your device’s battery size, charge rate, and how you use the bank during each session.
Quick Reference: Typical Phone Sizes Vs Expected Full Charges
This table gives a fast estimate using a usable range of 26–31Wh from a 10,000mAh pack. Pick the row near your phone’s battery size.
| Phone Battery (mAh) | Approx. Energy (Wh) | Estimated Full Charges |
|---|---|---|
| 3,000 | ~11–12 | ~2.2–2.8 |
| 3,500 | ~13 | ~2.0–2.4 |
| 4,000 | ~15 | ~1.7–2.1 |
| 4,500 | ~17 | ~1.5–1.8 |
| 5,000 | ~19 | ~1.3–1.6 |
How Many Full Charges From A 10,000 mAh Bank: Real Math
The trick is to compare energy, not just the mAh number on the label. Convert each side to watt-hours (Wh). The basic relation is Wh = (mAh × V) ÷ 1000. Airlines use the same math to label lithium packs by energy. See the IATA watt-hour definition for the formal wording.
Now apply it:
- Power bank energy at cell level: 10,000mAh × 3.7V ÷ 1000 ≈ 37Wh.
- Usable energy after conversion: real packs waste some energy raising cell voltage to the USB output and dealing with heat. Many quality models land in the 70–85% window. Anker pegs internal conversion near the low-80s in its help docs; add cable and device losses and you end up near ~26–31Wh available to your phone. Source: Anker efficiency explainer.
- Your phone energy: a 4,500mAh phone battery sits around 3.85V nominal, so ~4,500 × 3.85 ÷ 1000 ≈ 17Wh.
With that, a 10,000mAh pack feeding a 4,500mAh phone gives about 26–31Wh ÷ 17Wh ≈ ~1.5–1.8 full charges. A compact 3,000mAh phone rises closer to two and a half charges. Bigger 5,000mAh phones sit near one and a half.
Why The Real Count Drops Versus The Label
Voltage Conversion And Heat
The cells store energy near 3.6–3.7V. USB-A and standard USB-C ports push 5V, while Power Delivery ramps higher. That step-up isn’t perfect. The electronics burn a slice as heat, and cables add resistance. Expect total round-trip losses that push usable energy down to the 70–85% band.
Fast Charge Overhead
Faster profiles raise voltage and current. That trims efficiency a bit, especially at the tail of a charge when the phone manages heat more aggressively. USB-IF’s Power Delivery spec allows wide voltage steps up to 240W for bigger gear; it’s great for speed, but the headline wattage doesn’t change the energy inside a 10,000mAh pack. See the USB-IF overview for context on PD power levels.
Screen-On And Background Drain
Scrolling, navigation, and camera use while charging siphon energy that never reaches the battery. That turns a “full charge” into a partial top-up, even though the bank worked the whole time.
Worked Examples You Can Copy
Compact Phone ~3,000 mAh
Energy target ≈ 11–12Wh. Usable bank ≈ 26–31Wh. Expect roughly two and a bit, up to nearly three if you keep the screen off and charge at a moderate rate.
Mid-Size Phone ~4,000 mAh
Energy target ≈ 15Wh. Usable bank ≈ 26–31Wh. That gives about 1.7–2.1 full cycles. Real-life lands near the middle.
Large Phone ~5,000 mAh
Energy target ≈ 19Wh. Usable bank ≈ 26–31Wh. Plan for 1.3–1.6 full cycles. If you watch video while charging, expect the lower end.
What Changes The Result
Cable Gauge And Length
Thin or long leads waste energy as heat. Short, well-made USB-C cables reduce that loss. If your bank supports 3A or 5A output, match it with a cable rated for the same.
Port And Profile Choice
Charging a phone at 9V or 12V can be slightly less efficient than 5V for the same energy moved, especially on small batteries. When you’re squeezing one last top-up, a slower profile can stretch the pack.
Temperature
Cold slows the chemistry, and high heat triggers protective throttling. Room-temp charging wastes less energy and treats the cells gently.
Device Health
Older phone batteries hold less than their original rating. A worn 5,000mAh pack might behave closer to 4,000–4,300mAh, which changes how many full charges you see.
Reality Check: Two Phones, One Bank
Sharing one 10,000mAh bank between two modern phones drains it fast. If each phone has a 4,500–5,000mAh battery, you’ll roughly refill one and give the second a strong partial. For pairs with one small and one large phone, you might land near two totals, but that’s the ceiling for most setups.
Second Reference Table: Other Gadgets You Might Charge
These ballpark counts use the same 26–31Wh usable energy assumption. Actual results vary by model and charge rate.
| Gadget | Typical Battery (mAh) | Estimated Full Charges |
|---|---|---|
| Wireless Earbuds Case | 400–600 | ~8–12 |
| Smartwatch | 250–450 | ~10–20 |
| Action Camera | 1,200–1,800 | ~2–4 |
| Handheld Console (Small) | 3,500–5,000 | ~1.3–2.4 |
| Tablet Mini | 5,000–6,000 | ~0.9–1.5 |
Travel Note: Wh Limits And Labels
Airlines talk in watt-hours, not mAh. A 10,000mAh bank sits near 37Wh, well under common limits. The energy label is often printed on the case. If you need the math, the IATA formula above is the standard. Many aviation pages cite the same rule: Wh = V × Ah. Packs under 100Wh fly in carry-on on most airlines, while bigger units need approval and often a cap on quantity.
Ways To Stretch Each Milliamp
Charge With The Screen Off
Big panels and high refresh rates sip from the same pool. A dark, idle screen gives that energy to the battery instead.
Stop At 80–90% When You Can
The final few percent move slow and waste more heat. If you just need to reach bedtime, cut the cable early and save the pack for later.
Pick The Right Cable
Use short, certified USB-C leads. Keep frayed or mystery cables out of the kit.
Avoid Daisy Chains
Running through adapters or hubs adds extra conversion stages, each nibbling energy. Go bank → cable → device.
Choosing Between 10,000 mAh And Larger Packs
A 10k bank is compact and light, great for city days, commutes, and a night away. Step up to 20k when you carry power-hungry phones, shoot a lot of video, or run a console on long trips. Bigger units weigh more, so balance size against what you truly need.
Simple Steps To Calculate Your Own Number
- Find your device battery in mAh. If you only see Wh, convert to mAh with mAh = (Wh × 1000) ÷ V.
- Turn your 10,000mAh bank into Wh: 10,000 × 3.7 ÷ 1000 ≈ 37Wh.
- Multiply by an efficiency factor: pick 0.7–0.85 based on cable quality and charge speed. That yields ~26–31Wh usable.
- Divide usable Wh by your device Wh. The result is your expected full charges.
Key Takeaways You Can Trust
- A 10k bank usually means ~1.5–2.5 phone charges, shaped by battery size and losses.
- Energy math beats mAh slogans. Compare Wh to Wh for honest expectations.
- Efficiency matters. Quality electronics and good cables keep you closer to the top of the range.
- Fast isn’t free. Higher-rate profiles can trim the final tally a bit.
Method Notes
This guide converts capacity to Wh and applies a realistic efficiency band supported by public sources. The IATA watt-hour rule defines the core formula used across travel and labeling, and the Anker efficiency explainer reflects typical conversion loss in real hardware. Figures here are ranges, not promises, since devices, charge profiles, and cables vary.