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Day-ahead and real-time markets

Most US power markets run twice. The day-ahead market sets prices and schedules for each hour of the next day. The real-time market settles the differences as the day actually unfolds.

Also called DA and RT prices, day-ahead spread

Formula

Day-ahead spread = day-ahead price − real-time price

Same node
Both prices at the same location
Same hours
Pair each hour before you average

With real numbersERCOT, 2025 averages: $34.04 day-ahead − $33.10 real-time = $0.94 per MWh

In the data

7.5% vs 3.6%of ERCOT node hours with negative prices in 2025, real-time against day-ahead

Day-ahead averaged above real-time in all seven markets in 2025. Real-time prices went negative more often in all seven.

Average plant node price, 2025, $/MWh
  • Day-ahead
  • Real-time
  1. CAISO$35.17$33.88
  2. ERCOT$34.04$33.10
  3. ISO-NE$66.30$64.12
  4. MISO$37.33$36.34
  5. NYISO$59.99$59.31
  6. PJM$44.93$44.43
  7. SPP$26.08$24.84

ISO day-ahead and real-time prices, 2025. Mean of yearly averages at 3,136 plant pricing nodes with a full year in both markets.Open the map

Built from InfraMap's 2025 data with the same tools the analyst uses.

Common mistakes

  1. Mixing the two markets in one average. Day-ahead and real-time prices answer different questions, so say which one you use.
  2. Using real-time output as if it were the day-ahead schedule. A plant can be scheduled for one amount and deliver another.
  3. Subtracting averages over different hours. Pair the same node and the same hours first.

How the InfraMap analyst defines it

Different market schedules, dispatch and settlement timeframes. Do not substitute observed real-time exports for a cleared day-ahead schedule.

Reviewed October 1, 2026 against the references below. The analyst and the MCP server answer with this definition.

Primary references

See it for any US plant

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