Camera Battery Runtime Calculator — Capacity, Power Draw & Recording Time
Battery and camera rig
Estimated powered runtime
Target coverage
One battery covers about 63% of the 4-hour target. Plan for 2 equal batteries.
The target requires about 155.56 Wh of rated capacity at a 90% usable-capacity assumption.
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How to estimate camera battery runtime
- Use watt-hours when the label provides them. Wh already combines electrical capacity and nominal voltage, so it is the clearest value for comparing different battery systems.
- Otherwise enter mAh and nominal voltage. Do not use the fully charged voltage. The calculator converts the battery rating to Wh.
- Enter the complete rig's average draw. Include any monitor, external recorder, wireless transmitter, lens motor, follow focus, adapter, or other accessory powered from the same pack.
- Choose a usable-capacity percentage. The default 90% is only a planning assumption. Replace it with a measured value or a more conservative allowance for the shoot.
- Add a target time if useful. The result shows target coverage and the whole number of equal batteries required.
- Test the actual configuration. Record in a representative mode with the real accessories, display settings, temperature, and battery condition.
Camera battery capacity and runtime formulas
Battery energy in watt-hours combines charge capacity and nominal voltage. For a battery rated in milliamp-hours:
capacity (Wh) = capacity (mAh) ÷ 1,000 × nominal voltage (V)
For n equal batteries and usable-capacity fraction u:
usable energy (Wh) = Wh per battery × n × u
runtime (hours) = usable energy (Wh) ÷ average power (W)
When a target recording time is entered, the calculator reverses the relationship:
required rated capacity (Wh) = target hours × average power (W) ÷ u
required batteries = round up(required capacity ÷ Wh per battery)
A watt-hour is energy delivered by one watt for one hour. At a steady 35 W, a rig consumes 35 Wh each hour. Actual camera draw is rarely perfectly steady, so the average must represent the intended shooting setup.
References: NIST Guide to the SI — electrical unit conversions; SmallRig V-Mount Battery Guide — Wh, voltage, draw, and runtime examples.
What changes real camera recording time?
| Factor | Why it matters | How to account for it |
|---|---|---|
| Recording mode | Resolution, frame rate, codec processing, and sensor mode can change camera load. | Measure or test in the exact recording mode. |
| Accessories | Monitors, recorders, wireless video, focus motors, and USB devices add to battery draw. | Add every device powered by the same battery. |
| Conversion and cutoff | Voltage regulators consume energy, and the battery or camera may shut down before every rated Wh is delivered. | Reduce the usable-capacity percentage. |
| Battery condition | Age, cycle history, state of charge, high load, and cold temperatures can reduce delivered energy. | Use a conservative factor or measured discharge result. |
| Camera activity | Autofocus, stabilization, display brightness, playback, pre-record, and wireless functions vary over time. | Use average draw from a representative test, not only idle power. |
| Non-battery limits | Media capacity, overheating, clip limits, and operational pauses can end continuous recording first. | Plan those constraints separately from powered runtime. |
Planning estimate, compatibility, and battery safety
This calculator estimates energy runtime; it does not validate electrical compatibility. Confirm voltage range, polarity, connector wiring, maximum continuous current, output-power rating, cable rating, battery-management limits, and the equipment manufacturer's instructions before connecting anything. Never improvise series or parallel battery wiring.
The result is not a guarantee of uninterrupted recording. Battery gauges and published capacities have tolerances, while real loads and conditions change. Keep a suitable reserve, use healthy batteries and approved chargers, and stop using any pack that is swollen, damaged, unusually hot, leaking, or recalled. For critical productions, perform a timed test and provide independent backup power.
Camera battery runtime FAQ
How do I calculate runtime from Wh and watts?
Divide usable watt-hours by average watts. A 98 Wh battery at 90% usable capacity provides 88.2 Wh; at an average 35 W, the estimate is 2.52 hours, or about 2 hours 31 minutes.
How do I convert mAh to Wh?
Divide mAh by 1,000, then multiply by nominal voltage. A 6,800 mAh, 14.4 V battery is 6.8 Ah × 14.4 V = 97.92 Wh. The same mAh rating at a different voltage represents a different amount of energy.
Should I use camera power consumption or battery output watts?
Use the rig's average consumption. A battery's maximum output wattage is a compatibility limit, not the load it forces into the camera. The battery must still support the rig's peak and continuous draw.
What usable-capacity percentage should I enter?
Use your own measured result when possible. Otherwise choose a planning allowance that reflects battery health, temperature, load, conversion losses, cutoff, and how much reserve the shoot needs. The 90% default is an editable assumption, not a promise.
Can I multiply runtime by the number of batteries?
Yes when equal, fully charged batteries are used sequentially with negligible changeover time. It also applies to a properly designed compatible bank whose rated energies can be combined. Hot-swap behaviour and unequal batteries require system-specific guidance.
Does the estimate include a monitor and wireless transmitter?
Only if their average watts are included in the entered total rig draw. Accessories powered from separate batteries should not be counted against this battery pool.
Why can a camera stop recording before the calculated time?
The estimate covers electrical runtime only. A full card, thermal shutdown, file-duration limit, battery voltage cutoff, or other camera restriction can stop a recording earlier.
Does this calculator save my equipment details?
No. Calculation, clipboard copying, and CSV generation run locally in your browser.