Old phone vs ESP32 NerdMiner: which is the better tiny miner?
ESP32 lottery miners are having a moment — a cute little screen on your desk hashing Bitcoin. But the phone in your drawer is a far more capable miner, and nobody selling gadgets will tell you by how much. Here's the honest comparison, with real numbers and the caveats intact.
1 · The short, honest answer
2 · Head-to-head (Bitcoin / SHA256d)
SHA256d is the only thing an ESP32 can do, so it's the only apples-to-apples column. Here's how they stack up on the Bitcoin solo lottery:
| Device | SHA256d hashrate | Power | Cost |
|---|---|---|---|
| ESP32 NerdMiner (NerdMiner firmware) | ~50–80 kH/s | ~1–2 W | ~$20–40 |
| ESP32-D0 (NMMiner firmware, fastest) | ~1,035 kH/s | ~1–2 W | ~$20–40 |
| ESP32-S3 / C3 (NMMiner firmware) | ~400 kH/s | ~1–2 W | ~$25–50 |
| Old phone, 1 big core + Primo | ~16 MH/s | ~2–3 W | $0 (own it) |
| Old phone, 8 cores + Primo | ~90 MH/s | ~4–8 W | $0 (own it) |
Phone figures are measured with Primo ARM Miner on RK3588 and Galaxy S10+-class hardware; ESP32 figures are the project-published NerdMiner and NMMiner numbers. NerdMiner's own firmware runs ~49–78 kH/s on common boards (up to ~256 kH/s on an ESP32-S3); NMMiner is the faster firmware — ~1 MH/s on an ESP32-D0, ~400 kH/s on the S3/C3. Power is ~1 W for the chip and ~1–2 W board-level with the display (active-WiFi draw is 95–380 mA at 3.3 V). Even against the fastest ESP32, a single phone still does ~15–90× the hashrate, and mines coins no ESP32 can. Your phone's exact rate depends on its SoC and thermals.
3 · The part the gadget listings skip
Hashrate isn't even the most interesting difference. An ESP32 can only compute SHA256 — so the Bitcoin solo lottery is the only thing it does, and Bitcoin is exactly the coin where a small miner has no realistic chance against ASICs. A phone is a full general-purpose CPU, so it can mine the algorithms that were designed to be mined on CPUs:
- Verus (VerusHash 2.2) — CPU-first by design; a phone does ~7.5 MH/s across 8 cores. How to mine Verus →
- Monero (RandomX) — the flagship CPU coin; a phone does ~700 H/s. RandomX needs 256 MB–2 GB of RAM, which an ESP32 simply doesn't have. How to mine Monero →
- Litecoin + Dogecoin (merged scrypt) and Bitcoin (SHA256d) too, if you want them.
Those first two are where a CPU earns small-but-real amounts instead of a pure lottery ticket. An ESP32 can't touch either. So the honest framing isn't "phone is a faster NerdMiner" — it's "a phone plays a different, better game entirely."
4 · Reality check (so nobody's disappointed)
5 · When the ESP32 is still the right call
We're not here to trash a fun project. An ESP32 NerdMiner genuinely beats a phone when:
- You want a silent, always-on desk ornament with a live block-odds display — a phone mining full-tilt is warm and busy.
- You don't want to tie up a phone you use for other things, or babysit its battery and heat.
- You specifically want the ~1 W, leave-it-for-years form factor, and the Bitcoin-lottery ritual is the whole point.
- You enjoy the hardware-tinkering hobby for its own sake — that's a legitimately good reason.
6 · Try it on a phone you already own
Primo ARM Miner is a free, open-source (GPL-3.0) ARM-native miner. One ~508 KB binary, or a sideloaded Android APK. No sign-up, no cloud, mines straight to your own wallet.