Should i explain the bar situation?

We were in this situation too. We're supplying all the wine on the tables for dinner, but after that the bar will be a toonie/cash bar. Nowadays, no one has cash on them and our venue doesn't have a bank machine close by. I wanted to add something on the wedding invitation insert, but a lot I read online made it seem that it was 'tacky' to do so. But I took the time to word it nicely and said something like "Wine will be provided for dinner, and we have a fully stocked cash bar for your enjoyment. We look forward to celebrating with you!" I figured it was better for people to have the heads up and have cash on them rather than show up and not have anything. We live in a different world now (cashless) and weddings need to evolve with that!

OK, that's fair. I think I just assumed based on how your description of your guests. Most big drinkers tend to go for something else other than wine and light/non-drinkers might have a sip here and there but probably wouldn't mind if their half bottle got swapped for a rum and coke or something.

I would ask if you can switch the allocated wine to either a beer or have an alcoholic punch bowl that's available to everyone. They may say no but it doesn't hurt to ask. You'll get more bang for your buck that way, especially if you and your guests aren't big on wine.

We also did a consumption bar but we only put out wine bottles at tables we know for sure will actually drink it and even then, we had a lot leftover.

If you truly think things will balance out and the total number of drink orders won't surpass what you budgeted for, don't bother explaining. You'll just confuse people.

If you think it'll go over by a small amount (20 or so drinks), I would just suck it up and pay for it.

Only say something if you absolutely think it'll get out of hand, which I highly doubt it will since you're allocating 7+ drinks per person to a group where a good chunk are not big drinkers. But you really should implement the drink ticket system if that's the case.

By the way, a typical bottle of wine is five servings so giving each guest half a bottle would muck up your calculation. Unless you're at a nice winery, I would honestly just put that wine budget to extra drinks since most venue house wines are terrible and the vast majority of people would much prefer another drink of choice if given the option.