Tools in This Collection
Price Per Unit Calculator
Compare product value by calculating cost per ounce, liter, or unit
Tip Calculator
Calculate tip amounts and split bills between any number of people
Shrinkflation Calculator
Quantify effective price increases when package sizes shrink
Sports Betting Parlay Calculator
Calculate combined odds and payouts for multi-leg parlay bets
Bulb Wattage Equivalent Calculator
Find LED equivalent wattage for incandescent bulbs
Image DPI Calculator
Calculate minimum image resolution needed for print quality
Smart Shopping Calculation Workflow
Shopping calculations go beyond simple price comparisons — you need to account for unit differences, quantity changes, tip splits, and energy cost trade-offs. These tools handle the math for common buying decisions.
The most useful tool for grocery and bulk shopping is the Price Per Unit Calculator. Enter the price and size of two products in any units (oz, lbs, kg, fl oz, liters, count) and it calculates cost per unit for each and shows which is the better value. A 32 fl oz bottle at $4.49 = $0.14/oz. A 12 oz bottle at $1.99 = $0.17/oz. The large bottle is cheaper even at a higher total price.
The Shrinkflation Calculator quantifies how much a product's effective price has increased when the package size was reduced without a price change. A bag of chips that went from 10 oz to 8.5 oz at the same $3.99 price = a 17.6% effective price increase. This tool makes the hidden cost increase visible.
For dining, the Tip Calculator splits any bill by number of people and calculates tip percentages. Standard tip rates: 15% for adequate service, 18-20% for good service, 20-25% for excellent service. A $85 dinner bill split 4 ways with 20% tip = $25.50 per person.
For home energy, the Bulb Wattage Equivalent Calculator finds the LED equivalent for incandescent bulbs: a 60W incandescent = 8-10W LED, a 100W incandescent = 14-15W LED. LEDs use 75-80% less energy for equivalent light output. The Image DPI Calculator determines print quality requirements — a 4×6 inch print at 300 DPI requires a 1200×1800 pixel image minimum. The Sports Betting Parlay Calculator calculates combined odds and potential payouts for parlay bets.
Frequently Asked Questions
How do I calculate price per unit for different size products?
Divide the price by the quantity in the same units. For 32 fl oz at $4.49: $4.49 / 32 = $0.14 per fl oz. For 12 oz at $1.99: $1.99 / 12 = $0.17 per oz. Lower cost per unit is the better value. The Price Per Unit Calculator handles different units automatically — you can compare a product sold by weight against one sold by volume.
What is the standard tip percentage for restaurant service?
15% is the baseline for adequate service. 18-20% is standard for good service and is now expected in most US restaurants. 20-25% is appropriate for excellent service. 10% or less signals dissatisfaction. Some restaurants add an automatic gratuity (18-20%) for large parties — check the bill before adding more. The Tip Calculator handles any percentage and splits the total by the number of diners.
How much energy does switching to LED bulbs actually save?
LED bulbs use about 75-80% less electricity than equivalent incandescent bulbs. A 60W incandescent replaced by an 8W LED saves 52 watt-hours per hour of use. Running 5 bulbs for 5 hours per day, the annual savings are about 475 kWh — approximately $57-95 per year depending on electricity rates. The Bulb Wattage Equivalent Calculator shows the exact LED equivalent for any incandescent wattage.