Calculation

BTC mined per day = 6.25 / (27452707696466.3 * (2^32) / 90000000000000 / 86400) = 0.000412184 btc per day

BTC mined per day = block reward / (difficulty * (2^32) / projects hash rate / seconds in a day)

Important:
Change the number for the Difficulty and/or Hash Rate above in accordance with your own mining project needs.
Hash Rate in this formula is in units of H/s (hashes per second) and NOT Gigahashes per second (GH/s) or Terahashes per second(TH/s).
2^32 (in excel) or 2 to the power of 32, is used in this example to convert Difficulty in Terahashes per second (Th/s) to Hashes per second (H/s).

Current Difficulty: 27452707696466.3 https://www.bitrawr.com/difficulty-estimator
Current Network Hash Rate Th/s: https://ycharts.com/indicators/bitcoin_network_hash_rate
Block Reward: 6.25 (Next Bitcoin halving in April or early May 2024)
Block Frequency mins: 10
Your projects hash rate per second (H/s): e.g. 90000000000000

You will also need the current price of 1 Bitcoin:
https://www.bitcoinprice.com/