Locational Marginal Pricing (LMP) is the standard method U.S. wholesale electricity markets use to price power at thousands of individual locations across the grid, rather than at a single system-wide price. If you’ve ever wondered why the wholesale price of electricity can differ significantly between two points on the same grid, LMP is the reason.
The Three Components of LMP
Every LMP is made up of three parts: the system energy price (the marginal cost of generating the next unit of electricity system-wide), a congestion component (the added cost when transmission constraints force the grid operator to run more expensive generation to serve a location), and a losses component (the cost of physical energy lost as heat during transmission).
Why It Matters
LMP gives grid operators a price signal that reflects real physical conditions on the grid at that moment and location. When a transmission line is congested, LMP at the constrained location rises to reflect the true cost of serving that area — which is why traders, utilities, and generators watch nodal LMP data closely rather than relying on a single average price.
Where to Find LMP Data
All seven U.S. ISOs/RTOs (CAISO, ERCOT, ISO-NE, MISO, NYISO, PJM, and SPP) publish LMP data through their public market data portals, and the U.S. Energy Information Administration’s Wholesale Electricity Market Portal aggregates data across these regions. Watts & Wire’s data dashboards pull from these same public sources — see our Data Sources & Disclaimers page for details.