Day-ahead vs. real-time
Every afternoon the day-ahead market prices tomorrow, hour by hour. This page grades that bet against what the grid actually paid.
The day, priced twice
Jul 12 · CT · 8-zone average- - day-ahead — real-timeWhere the misses landed
by zone and hour · click a zone to re-scope the chart aboveZone rows rank by today's average miss. zone mean of the load-zone settlement point prices.
The premium, by hour
the market's error, structurallyAverage of 182 paired hours since 2026-07-04. Fills in as the record grows.
The afternoon hours that decide 4CP are the hours day-ahead prices hardest. When this chart bulges violet after 2 PM, that is why.
Tomorrow, already priced
the bet, visible tonightJul 13, as the day-ahead market cleared it. Real time starts grading at midnight.
By zone, today
day-ahead vs real-time averages| Zone | Day-ahead avg | Real-time avg | Spread |
|---|---|---|---|
| AEN (Austin Energy) | $31.50 | $22.63 | −$4.61 |
| CPS (San Antonio) | $31.61 | $22.77 | −$4.60 |
| Houston | $30.89 | $22.70 | −$4.32 |
| LCRA | $31.37 | $22.60 | −$4.68 |
| North (DFW) | $31.14 | $22.65 | −$4.04 |
| Rayburn | $31.05 | $22.73 | −$3.92 |
| South | $30.07 | $22.72 | −$4.56 |
| West | $33.36 | $23.68 | −$6.23 |
Real-time averages cover graded hours only. Full interval detail is on the prices page.
What is the day-ahead market?
ERCOT runs a voluntary day-ahead market that clears each afternoon. Buyers and generators lock in a price for every hour of tomorrow, published around 12:30 CT. The real-time market then settles what each hour actually cost, in 15-minute intervals.
What is DART?
Trader shorthand for the day-ahead to real-time spread. On this page the spread is real time minus day-ahead, so a positive number means the hour settled above its day-ahead price and a negative number means day-ahead paid a premium.
Why do the two prices differ?
The day-ahead price embeds a forecast of weather, demand, and which plants will run. Real time is the grid as found: a hotter afternoon, a plant tripping offline, or wind underdelivering shows up in the real-time price first. The spread is the market grading its own forecast, in dollars.
Is day-ahead usually higher?
Overnight hours often settle under their day-ahead price, and scarcity afternoons can blow through it by hundreds of dollars. The by-hour chart on this page shows the shape as it accumulates. Both markets can also clear negative.
Where does this data come from?
ERCOT's public MIS reports: day-ahead settlement point prices and real-time 15-minute settlement point prices for the eight load zones, the same feeds behind the prices page. On daylight-saving switch days the grid honestly shows 23 or 25 hours.