Quick answer: Tbilisi runs about EUR 55 per day mid-range - noticeably less if you eat local and walk. Cheapest window: April-June and September-October - warm days, cool evenings and the autumn wine harvest season, avoid the humid heat of late July-August.
What things actually cost
khinkali dumpling
0.50 EUR
metro or bus ride
0.35 EUR
cappuccino in a cafe
2 EUR
adjaruli khachapuri
6 EUR
private sulfur bath room (1 hour)
20-30 EUR
dinner for two with wine at a good restaurant
25-35 EUR
Eat well for little
Khinkali - juicy soup dumplings you eat by hand, about 0.40-0.60 EUR each, order 5-10 at a spot like Zakhar Zakharich
Adjaruli khachapuri - the boat-shaped cheese bread with egg and butter, about 5-7 EUR and easily shared
Pkhali and badrijani - walnut-paste vegetable starters, a spread of both about 4-6 EUR
Mtsvadi - grilled pork skewers over vine embers, around 5-7 EUR a portion
Glass of natural qvevri wine - Georgia has 8,000 vintages of history, 3-4 EUR a glass in a wine bar
Money mistakes to avoid
Hailing street taxis and negotiating - just use the Bolt app, most rides across the center cost 2-4 EUR with no haggling
Matching Georgian hosts toast for toast with chacha - it is 50-60 percent alcohol and the toasts do not stop, sip and pace yourself
Skipping the public sulfur baths because the private rooms seem fancier - a public session costs a few euro and a private room with scrub is still only about 20-30 EUR, book the kisi scrub either way
Wearing shorts or uncovered shoulders to churches - carry a scarf, monasteries like Jvari enforce dress codes at the door
Transport without the tourist tax
From the airport, a Bolt to the center costs about 10-12 EUR (30 minutes) or bus 337 runs 24/7 for under 1 EUR. In town use the metro and buses with a Metromoney card at about 0.35 EUR per ride, plus Bolt for anything the metro misses.