A standard overhead 100A to 200A upgrade runs $1,800 to $5,500, with most homes between $2,800 and $4,200, and the permit adding $150 to $400 on top. Underground service moves it to $5,000 to $8,000 where the cable has to be trenched. Example ranges only; pricing depends on the service entrance.
Do you actually need it
An electrical panel upgrade is not a full panel
These are two different problems and they have two different prices. A full panel means every breaker slot is used. A service that is genuinely undersized means the total load your home draws is close to what the incoming conductors and main breaker can carry. The first is often solved with a subpanel installation for a fraction of the cost.
The way to tell them apart is a load calculation, and it is arithmetic rather than opinion. We total the fixed loads, apply the demand factors the code sets out, and compare the result against your existing service.
A 100A service in a house with gas heat, gas water heating and no electric cooling usually has more headroom than the homeowner expects. The same 100A service in an all-electric house that has just added a level 2 charger often does not.
Where the panel itself is the problem rather than the service, a panel and breaker inspection will say so, and you can stop there.
