Free tool · Data & IoT
IoT battery life: PSM and eDRX estimator
Estimate battery life for LTE-M and NB-IoT devices from reporting interval, time connected per report and power-saving settings.
- Battery life
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- Average current
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- Charge used a day
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Typical module values; radio conditions, temperature and firmware change real life. Compare settings, then measure a prototype.
How this works and its limits
Runs in your browser: what you enter stays on your device and is never uploaded.
The estimate adds up the energy of each wake-up, transmission and sleep period over a day, using typical module current values and the PSM and eDRX timers you choose. Battery capacity and self-discharge set the result.
Real battery life depends on radio conditions, temperature and firmware. Use the estimate to compare settings, then measure a prototype.
Data sources and licences
Operator names, brands and codes shown here are public reference data compiled from national regulators and other public sources. Their appearance does not indicate any partnership, endorsement, agreement or connectivity between unicomam.com and the named operators. All trademarks belong to their owners. Data is provided “as is” with no warranty; verify against the official source before relying on it for routing, billing or compliance decisions.
Regulatory information is for reference only and is not legal advice; check the regulator link and the “last verified” date.
Calculations follow 3GPP TS 23.038 / 23.003 / 27.007 / 36.101 / 38.101 (Release 18). This tool is not affiliated with or endorsed by 3GPP or ETSI.
How PSM and eDRX save power
Most battery-powered IoT devices spend nearly all their time asleep. Power Saving Mode (PSM) lets a device switch its radio off between reports while staying registered on the network, so it does not have to attach again each time it wakes. Extended discontinuous reception (eDRX) keeps the device reachable but lets it listen for incoming messages far less often, from about 20 seconds to several hours between listening windows.
A battery budget has three parts. While the device is connected, sending a report and waiting for the network to release it, the module draws tens to hundreds of milliamps. In the idle period that follows, it listens for paging at a few hundred microamps to a milliamp. Asleep in PSM, it draws only a few microamps. Because the connected current is so much higher, a few seconds of connection can cost more than a whole hour of sleep.
That is why the reporting interval and the time connected per report decide most of a device's battery life. Halving the number of reports nearly doubles the life of a PSM device; shortening the connection, by sending less data, avoiding retries and letting the network release the connection quickly, helps almost as much. PSM suits devices that only need to talk on their own schedule, while eDRX suits devices that must be reachable, such as a camera or a lock that waits for a command, at the cost of a higher sleep current.
The network sets the final values. A device requests its PSM and eDRX timers, but the network grants the values it supports, which can be shorter than requested or not offered at all. Coverage matters too: in weak signal, LTE-M and NB-IoT repeat transmissions to get through, which stretches the connected time and the energy of every report.
The battery itself changes over many years. Self-discharge removes a share of the capacity every year, and cold temperatures lower the capacity a device can use, so a design that looks good on paper should keep a margin. Compare settings with an estimate, then confirm on a prototype in the field.