Chi Cost Table
These costs describe the native xian_vm_v1 runtime. Use readonly simulation against the target node for a complete operation estimate; the local Python harness has a separate metering implementation.
Accounting
chi_used = (raw_meter_cost // 1000) + 5The result is capped by the transaction's submitted chi limit.
| Item | Raw cost |
|---|---|
| storage read | 2 per encoded key/value byte |
| storage write | 25 per encoded key/value byte |
| submitted transaction | 1 per byte |
| returned value | 1 per byte |
| cross-contract dispatch | 10,000 per call, plus called work |
VM computation and host operations use the fixed xian_vm_v1 gas schedule.
Fee Conversion
| Setting | Value |
|---|---|
| base transaction cost | 5 chi |
| initial paid-mode conversion in canonical bundles | 20 chi per XIAN |
The effective conversion rate is on-chain at chi_cost.S:value and can be changed by validator governance. Paid fees use chi_used / chi_rate.
In free_metered mode the runtime reports the same chi usage but creates no execution-fee debit or fee-derived reward.
Resource Limits
| Limit | Value |
|---|---|
| metered storage-write byte budget | less than 128 KiB, including encoded keys and values |
| submitted contract source | 128 KiB |
range(...) and bounded sequence repetition | 131,072 entries |
| bounded binary allocation and string repetition | 128 KiB |
| default node simulation chi budget | 1,000,000 |
Sequence entry counts and encoded byte counts are different units. A list of large values can cost much more than a list of the same length containing small integers. Return bytes are metered; the Python harness's separate 128 KiB return-value limit is not a general native-VM return-size guarantee.
ZK Verification
| Operation | Raw cost |
|---|---|
| raw Groth16 verification base | 750,000 |
| raw public input | 50,000 each |
| raw payload byte | 50 each |
| registry-backed verification base | 500,000 |
| registry prepared-key setup | 250,000 |
| registry-backed public input | 50,000 each |
| registry-backed payload byte | 25 each |
Shielded protocol helpers also have fixed host-operation costs. Proofs are limited to 4,096 hex characters, raw verifying keys to 8,192 hex characters, public inputs to 32, and verifying-key IDs to 128 characters.
Optimization
- cache repeated state reads in local variables
- keep keys and stored values compact
- avoid unnecessary writes and cross-contract calls
- paginate scans and bound returned collections
- simulate the exact transaction before choosing a chi limit
See Chi and Metering for the fee modes and Estimating Chi for simulation.