LHR to Munich

This may help https://www.heathrow.com/connecting-flights plug in your flight info and see what the result is.

Assuming all goes well, it sounds like plenty of time. But...something to consider:

I assume this is on your inbound flight to Europe, arriving from North America (or from elsewhere, that's far away and an expensive flight). The connection to a Munich flight is relatively low-stakes. If you miss it, you will probably have multiple options to get to Munich, probably with relatively little pain/expense. So, almost 3 hours, looks low risk to me.

What I'd be much more focused on is the way back. Are you doing the same thing - one flight to LHR, then a separate ticket home on a long haul transatlantic flight? If so, there's a lot more at stake there: if you miss that flight and have to pay for a new one, you might need to take out a second mortgage (and you would probably have much fewer options to choose from).

I'm always more risk-tolerant with a connection on my flight into Europe (assuming the connection is in Europe, not North America). On the way back, I would want more than 2 hours 50 minutes in LHR to ensure I make my connection.

If your connection is not to a long (expensive to replace) transatlantic flight, then the above doesn't really apply so much.

Joe32F, thank you for link. Looks like it’s too soon to be able to use the website- we travel in September.
David, yes, this is our inbound flight from Northern California. We will be spending the night in London before our flight back home. It sounds like a doable plan. Thank you for the reassurance.

I recently arrived at LHR at 7:35 with a departure to Munich at 10:50. I had time to spare. All terminal 5.

For flights arriving and departing from the same Heathrow terminal, the minimum connection time is generally 60 minutes. With carry-on luggage only, you'll be able to stay airside for the connection (i.e., no need to go through passport control or customs); however, you'll need to go through security (as all connecting passengers do) to enter the departure terminal. The time needed to go through security is built into the 60 minutes. If your inbound flight is more or less on time, you will have plenty of time to make your connection. If it's late and you miss your connection, you'll be on your own for getting a new ticket, but you'll have plenty of options for that (e.g., low-cost carriers from other London-area airports the following day).

ETA: One thing to keep in mind that will make your connection a lot easier is if you can have your boarding pass in hand for your connecting flight when you arrive in Heathrow - which means checking in and printing the boarding pass before you leave California. You can check in online up to 24 hours before the flight, so any time after 9:20 AM, California time, on your day of departure.

One thing that may help your transfer if you have a boarding pass is if both your inward and outward flights use a gate in the satellites (B / C) rather than the main terminal (A). Then you can clear security at your departure satellite and not get co-mingled with people leaving from Heathrow. If either flight uses the main terminal this option is not available. You can only find out when you land if this applies.

I believe you will have to go through passport control, regardless of whether you have carry-on only. We did when connecting at LHR to Glasgow on the same ticket. We had to go through security again also. We had a 3 hr connection, but had to change terminals, and BARELY made it because our first flight was 30 minutes late.

Thank you for all the responses. Lots to consider and think about. One thing that helps I think, is that we arrive and depart from the same terminal, T5. Keeping our fingers crossed 2hrs 50 minutes will allow us to make the flight to our final destination.
Great tip on printing the boarding pass for the outbound flight. I hadn’t thought about that. Thank you!