FYRELINKZ — HOUSEHOLD PRICE WORKSHEET
Original recordkeeping template. Not an official inflation index or financial advice.

Compare the same currency, item and unit size.
Item / unit size:
Baseline date / unit price / quantity:
Current date / unit price / quantity:

Baseline spending = baseline price x baseline quantity.
Price-only comparison = current price x baseline quantity.
Price effect = price-only comparison minus baseline spending.
Current spending = current price x current quantity.
Quantity-and-mix effect = current spending minus price-only comparison.

Hypothetical example:
Baseline: $4.00 x 10 = $40.00
Current price at baseline quantity: $4.20 x 10 = $42.00
Price effect: $2.00
Current spending: $4.20 x 12 = $50.40
Quantity effect at current price: $8.40
Total spending change: $10.40, not all a price increase.

Repeat for your own comparable purchases. Record substitutions, discounts and missing bills. Do not label the result official CPI.