Compute
units.
▸ /reference — typical consumption
▸ /faq
What is a compute unit?
Solana's meter for execution work, the same role gas units play on Ethereum. Every instruction consumes CU as it runs; a transaction declares a budget and is killed if it exceeds it. Blocks also cap total CU, so budgets are the resource validators actually schedule.
Do I pay for the budget or for actual usage?
The priority fee is charged on your requested budget, not measured usage, which is the economic nudge to set accurate limits. Requesting the default 200,000 CU for a 5,000 CU token transfer pays 40 times more tip than needed.
How do I find my transaction's real CU usage?
Simulate it: simulateTransaction returns unitsConsumed, and explorers show CU for confirmed transactions. Set your limit slightly above the measured figure with a safety margin for state-dependent branches.
Why is the fee so small even with a tip?
Rates are in micro-lamports, millionths of a lamport, which is itself a billionth of a SOL. A generous 50,000 micro-lamport rate on a 200,000 CU budget is 10,000 lamports: a hundredth of a cent at most SOL prices.