# min_burn (/docs/hyperparameters/min-burn) Sets the lowest price a subnet can charge for a burned registration. Miners watch it because it is the cost of joining a quiet subnet; owners tune it to keep registration from ever becoming free while still letting the price decay to something affordable. ## How it works [#how-it-works] Every block, `update_registration_prices_for_networks` (in `pallets/subtensor/src/subnets/registration.rs`, run from `block_step`) decays the current burn price exponentially toward zero — and then clamps it into `[min_burn, max_burn]`. The same clamp is applied after each registration bumps the price by [`burn_increase_mult`](/docs/hyperparameters/burn-increase-mult). So with no registrations arriving, the price settles at exactly `min_burn` and stays there; `min_burn` is the resting price of an idle subnet. The value is stored in `MinBurn` as a rao amount (1 TAO = 1e9 rao). The chain default is 500,000 rao (τ0.0005). The owner-set extrinsic (`sudo_set_min_burn` in `pallets/admin-utils/src/lib.rs`) enforces two bounds: the new value must be **below 1 TAO** (`MinBurnUpperBound`) and **strictly less than the subnet's current `max_burn`**. Registration burns are recycled — they are subtracted from total issuance and can be re-emitted, which pushes halvings out (see [emissions](/docs/concepts/emissions)). ## Reading and setting [#reading-and-setting] ```bash btcli sudo get --netuid 12 --name min_burn btcli sudo set --netuid 12 --name min_burn --value 0.001 ``` Settable by the subnet owner or root. A value with a decimal point is a TAO amount (`0.001` = τ0.001); a plain integer is raw rao (`1000000` = τ0.001). ## Related [#related] * [`max_burn`](/docs/hyperparameters/max-burn) — the matching ceiling * [`burn_half_life`](/docs/hyperparameters/burn-half-life) — how fast the price decays back to this floor * [`burn_increase_mult`](/docs/hyperparameters/burn-increase-mult) — the bump per registration * [`registration_allowed`](/docs/hyperparameters/registration-allowed)