Upper limit on burn registration cost.
Current Value
Conversion: ÷ 10^9 (RAO → TAO)
The Big Picture
Burn cost adjusts with demand, but this caps how expensive it can get. Without a ceiling, extremely popular subnets could have absurd burn costs, pricing out participants. The cap ensures burn registration remains accessible even on high-demand subnets, though you'll compete for limited registration slots per block.
Why This Matters
This is your worst-case burn cost. Budget for this amount if planning burn registration on popular subnets. The actual cost is usually lower.
Example
With MaxBurn of 100 TAO, that's the most burn registration can ever cost. If a subnet is extremely popular and burn would exceed 100 TAO, it stays at 100 TAO. Competition then happens through timing (getting into the MaxRegistrationsPerBlock quota).
Common Questions
- What if I can't afford MaxBurn?
- Use POW registration instead, or wait for demand to cool and burn to drop. Or join a less popular subnet with lower costs.
- Is burn cost refundable?
- No, once paid you can't get it back. However, the TAO isn't destroyed - it goes to the subnet's liquidity pool. This is different from lock costs which can be recovered.
Use Cases
- Burn registration
- Cost limits
Code Examples
import { ApiPromise, WsProvider } from "@polkadot/api";
import { stringCamelCase } from "@polkadot/util";
const provider = new WsProvider("wss://entrypoint-finney.opentensor.ai:443");
const api = await ApiPromise.create({ provider });
// Query InitialMaxBurn constant
const value = api.consts[stringCamelCase("SubtensorModule")][stringCamelCase("InitialMaxBurn")];
console.log("InitialMaxBurn:", value.toHuman());
// Convert RAO to TAO if this is a balance value
const taoValue = value.toBigInt() / BigInt(1e9);
console.log("TAO:", taoValue.toString());Type Information
- Type
- u64
- Byte Size
- 8 bytes
- Encoding
- fixed
- Raw Hex
- 0x00e8764817000000
Runtime Info
- Pallet
- SubtensorModule
- First Version
- v101
- Latest Version
- v101
- Current Runtime
- v393