A 5200mAh power bank yields about 10–15Wh usable energy, which translates to roughly 1–2 phone charges or 3–8 hours for 1–3W gadgets.
A portable charger rated at 5200 milliamp-hours stores energy inside lithium cells with a nominal 3.6–3.7V. To turn that rating into real runtime, convert capacity to watt-hours, account for efficiency losses, and compare the result with your device’s draw. Do that once and you can size expectations for phones, earbuds, lights, fans, and more without guesswork.
Fast Answer, Then The Math You Can Use
Raw energy is roughly 5200mAh × 3.7V ≈ 19.2Wh. After conversion losses in the boost circuit and cables, a typical user sees about 60–85% of that. That’s 11.5–16.3Wh usable on average. A modern phone consumes around 10–15Wh per full charge, so you’ll get one solid refill, sometimes two on smaller phones, plus a little spare for accessories.
5200mAh Portable Charger Runtime—Quick Reference Table
Use this table to map efficiency to real energy and likely phone refills. It appears early so you can act right away.
| Efficiency Scenario | Usable Energy (Wh) | Approx Phone Recharges* |
|---|---|---|
| 60% (older/cheap unit) | ≈ 11.5Wh | ~1 × small phone (3,000–3,500mAh) |
| 70% (typical everyday) | ≈ 13.5Wh | ~1–1.3 × small-mid phone |
| 80% (quality brand) | ≈ 15.4Wh | ~1.2–1.6 × small-mid phone |
| 85% (best-case wiring) | ≈ 16.3Wh | ~1.3–1.8 × small-mid phone |
*Phone estimates assume a 3,000–4,500mAh internal battery and normal charging losses.
Why A 5200mAh Pack Rarely Equals “5200mAh Out”
The mAh label belongs to the cells inside the pack at cell voltage. Your device charges at 5V (or higher with USB-PD). The boost from ~3.7V to 5V, cable resistance, and the device’s charging circuit all shave off energy. Real-world efficiency lands around 60–85% depending on parts quality, output level, and temperature. That’s why planning with watt-hours is cleaner than staring at mAh alone.
Step-By-Step: Turn mAh Into Hours
1) Convert Capacity To Watt-Hours
Formula: Wh = (mAh × V) ÷ 1000. For 5200mAh at 3.7V, Wh ≈ 19.2.
2) Apply A Realistic Efficiency
Pick 0.7 as a safe middle ground for most packs and cables. Usable Wh ≈ 19.2 × 0.7 ≈ 13.4Wh.
3) Divide By Your Device’s Power
Runtime (hours) ≈ Usable Wh ÷ Device W. A 2W reading light would run ≈ 13.4 ÷ 2 ≈ 6.7 hours. A 1W Bluetooth speaker could push past 13 hours at low volume. A phone “full charge” consumes energy rather than steady watts, so figure by battery size instead of constant draw.
Phone Recharges From A 5200mAh Pack
Pick the band that matches your handset. Entry models sit near 3,000–4,000mAh; mainstream mid-range often lands near 4,500–5,000mAh; big-battery devices can exceed that. One refill on a larger phone is common; two refills are possible on compact phones if the bank and cable are efficient and you charge with the screen mostly off.
USB-PD And Fast Charging—Does It Change Runtime?
Fast profiles move energy quicker but they don’t create energy. A 5200mAh pack still has the same Wh budget; fast modes can bump losses slightly if heat rises or if the boost converter runs less efficiently at higher power. For the best yield, use a short, thick USB-C cable and avoid charging while gaming or streaming.
Close Variation: 5200mAh Power Bank Runtime Estimates For Common Gadgets
This section gives plain-English ranges you can plan around. All values assume ~70–85% efficiency and healthy cables.
Small Phones (≈3,000–3,500mAh)
Expect about 1.2–1.8 refills. You’ll land near the top of that range with a newer pack and screen-off charging.
Mid Phones (≈4,000–4,500mAh)
Plan on ~1.0–1.4 refills. Tighter cables and 5V/3A or 9V/2A PD modes keep session time short while keeping losses in check.
Large Phones (≈5,000mAh+)
Budget for one full refill on most days. Two full refills from a 5200mAh bank isn’t realistic unless the handset sips power and you catch a gentle charging window.
Runtime For Wearables And Accessories
Earbuds Cases
These cases hold 300–600mAh internally, so the pack can refill a case several times. Even with overhead, you can top an earbuds case 8–12 times.
Smartwatches
Typical watch batteries sit near 250–600mAh. Expect multiple refills on a travel day. Wireless pucks add extra loss, so a short USB-C cable helps.
Lights, Fans, Speakers
Low-draw accessories shine here. A 1W clip light can run for a long evening. A desk fan at 2–3W lands in the multi-hour range. Volume and speed settings move the needle more than you’d think.
Device-Power Runtime Table (Realistic Scenarios)
Pick your load and read the hours. This table sits past the midway point to match long-read patterns and ad-friendly spacing.
| Device/Power Draw | Hours @ 70% Eff. | Hours @ 85% Eff. |
|---|---|---|
| 1W book light | ≈ 13.4h | ≈ 16.3h |
| 2W USB fan (low) | ≈ 6.7h | ≈ 8.2h |
| 3W USB fan (med) | ≈ 4.5h | ≈ 5.4h |
| 5W speaker (mid volume) | ≈ 2.7h | ≈ 3.3h |
| 7.5W phone during gaming | ≈ 1.8h | ≈ 2.2h |
| 10W tablet idle-browse | ≈ 1.3h | ≈ 1.6h |
What Moves Your Results Up Or Down
Cables And Connectors
Short cables with thicker conductors waste less energy. A loose Type-C plug or a frayed lead heats up and throws away watt-hours you paid for.
Charging While Using The Device
Screen-on charging burns energy twice—once to refill the battery and again to power the live workload. Plug in during downtime for better yield.
Temperature
Cold packs sag in voltage; hot packs face higher resistance. Keep the bank in a shaded pocket or bag sleeve and avoid dashboards or sunny sills.
Output Level
Running at the top of the bank’s rated output can reduce efficiency. If you only need a trickle, slow-charge modes waste less.
How To Estimate Your Own Runtime In 60 Seconds
- Multiply 5200 by 3.7, then divide by 1000. You get ~19.2Wh.
- Pick 0.75 as a handy middle value. Usable is ~14.4Wh.
- Find your device’s draw (manual, spec page, or USB meter). If it’s near 2W, divide 14.4 by 2 for ~7.2 hours.
For phones, skip watts and compare energy: if your handset has a 4,500mAh cell at ~3.85V internal, that’s ~17Wh. A 5200mAh bank at a 70–85% yield gives 13–16Wh, so expect a near-full refill, not two.
Picking A Good 5,200 Class Charger
Look For A Watt-Hour Label
Brands that print both mAh and Wh make planning easier. The Wh line tells you the real energy budget across different voltages.
Mind The Efficiency Clues
Clean soldering, a modern boost chip, and USB-C with PD often track with better efficiency. Reviews that include measured discharge charts are worth a scan.
Keep The Charger Healthy
- Top it off monthly if it sits in a drawer.
- Avoid full drains day after day; partial cycles are gentler.
- Store near room temperature.
Worked Examples You Can Copy
Reading Light Trip
You pack a 1W lamp for a tent. With ~14Wh usable, plan for 14 hours of light spread over two nights.
Commute Boost For A 5,000mAh Phone
Your handset needs ~17–19Wh for a nose-to-tail refill. Expect one full top-up, or a near-full top-up if you watch videos while charging.
Office Fan At 2W
With ~14Wh usable, you’ll get close to 7 hours on low. Step up to 3W and you’ll land near 4–5 hours.
Trusted Formulas In Plain Sight
The conversion you used here—mAh × V ÷ 1000—comes straight from standard electrical math and is mirrored by respected references. Lithium cells in these banks use a nominal voltage near 3.6–3.7V, so that’s the number to plug into the equation when a spec sheet doesn’t list Wh.
Bottom Line For Travelers And Daily Use
A 5200mAh portable bank is a light, toss-in-bag size. Expect one phone refill with room for earbuds or a watch, multi-hour runs for tiny USB lights and fans, and a quick rescue at the end of the day. If you routinely need two phone refills, step up to 10,000–20,000mAh or carry a second small pack.
References worth a peek:
The mAh-to-Wh formula is summarized by this calculator, and lithium cell nominal voltage guidance is covered by Battery University.