One-Sentence Definition
DAG size is the size of a memory file (Directed Acyclic Graph) that GPUs must load into their VRAM to mine cryptocurrencies using the Ethash algorithm, which increases over time and determines whether your GPU has enough memory to mine.
Why It Matters for Solo Mining
If you’re solo mining Ethereum Classic or other Ethash coins with GPUs, the DAG size directly determines if your graphics card can even participate. Once the DAG grows larger than your GPU’s VRAM, that card becomes completely useless for mining that specific coin — no matter how fast it is. This is especially brutal for solo miners who might have invested in older GPUs only to find them obsolete when the DAG outgrows their memory capacity.
How It Works
The DAG (Directed Acyclic Graph) is a large data structure that gets generated every 30,000 blocks (called an “epoch”) and must be stored entirely in your GPU’s VRAM. When mining Ethash-based coins, your GPU constantly references this DAG file to compute shares and potential blocks. The DAG was intentionally designed to grow over time to make ASIC mining harder and keep GPU mining competitive.
The problem is that the DAG grows by about 8MB every epoch — roughly 23MB per year. This means a GPU with 4GB of VRAM that could mine Ethereum in 2016 couldn’t mine it by late 2026 when the DAG exceeded 4GB. The growth is permanent and predictable, so you can calculate exactly when your GPU will become obsolete for a specific coin.
Different Ethash coins have different DAG sizes depending on their blockchain height. Ethereum Classic’s DAG is smaller than Ethereum’s was because it has fewer total blocks, which is why older 4GB GPUs migrated to ETC after being kicked off ETH.
Example
Let’s say you have an older GTX 1060 6GB card. Ethereum’s DAG grew past 5GB in December 2026 (before switching to Proof of Stake), making your card unusable for ETH. But Ethereum Classic’s DAG was only around 3.5GB at that time, so the same card worked fine for ETC solo mining. As of 2026, ETC’s DAG is around 3.9GB, so even 4GB cards are getting close to retirement.