Everyday Calculators
27 free toolsHealth, school, kitchen, home, and planning calculators.
Everyday calculators cover the questions that are not really about code: BMI and daily calories, GPA and what you need on the final, exact age, dice and coin flips, baking ratios, coffee and rice ratios, turkey thaw times, pool and aquarium volumes, shipping weight, propane usage, and a seating chart builder. Each one cites the source of its formula (USDA, WHO, carrier rate guides) and says where the estimate stops being reliable.
Everything here runs in your browser: files and text are processed locally and never uploaded. The seating chart and contract builder save drafts only in your browser's local storage.
All 27 tools
Time Card Calculator
Total a weekly timesheet: clock in/out, unpaid breaks, overnight shifts, daily and weekly overtime, decimal hours, and pay. Print or export CSV.
BMI Calculator
Body mass index from height and weight, metric or imperial
Calorie Calculator
Daily calorie needs (TDEE) from age, size, and activity, with goal targets
Age Calculator
Exact age in years, months, and days, plus next birthday
GPA Calculator
Weighted and unweighted GPA from courses, credits, and grades
Grade Calculator
Current grade from weighted categories and what you need on the final
Dice Roller
Roll any dice — d4 to d100, multiple dice, modifiers, and totals
Coin Flip
Flip a fair coin, or many at once, with running tallies
Pool Volume Calculator
Gallons or liters for rectangular, round, oval, and kidney pools
Aquarium Volume Calculator
Tank volume, water weight, and heater and filter sizing for any tank shape
Coffee Ratio Calculator
Coffee and water amounts for any brew method and strength
Rice to Water Ratio Calculator
Water and cook time for any rice type and cooking method
Turkey Thaw Time Calculator
Fridge and cold-water thawing time by weight, with a start-by date
Meat Cooking Time Calculator
Roasting time and safe internal temperature by meat, weight, and doneness
Pizza Dough Calculator
Flour, water, salt, and yeast for any number of pizzas by style
Sourdough Calculator
Scale a sourdough recipe by hydration, starter, and loaf size
Bread Hydration Calculator
Baker’s percentages: hydration from flour and water, or water from a target
Cake Pan Size Converter
Scale a recipe between pan sizes and shapes by batter volume
Yeast Converter
Convert between active dry, instant, and fresh yeast
Sewing Fabric Yardage Calculator
Fabric yardage for curtains, quilts, tablecloths, and simple garments
Wedding Seating Chart Builder
Assign guests to tables, balance seats, and print or export the chart
Photography Contract Generator
Build a photography services contract and download it as a PDF
Shipping Dimensional Weight Calculator
DIM weight for UPS, FedEx, USPS, and DHL from package size
Pallet Loading Calculator
How many boxes fit on a pallet, with layer patterns and total weight
Propane Usage Calculator
How long a propane tank lasts for grills, heaters, and generators
Cocktail Dilution Calculator
Final volume, ABV, and dilution for stirred, shaken, and batched drinks
Secret Santa Generator
Draw names with exclusions and send each person a private reveal link
Guides
From the blog: the mechanisms, standards, and edge cases behind these tools.
- Baker's Percentages: Hydration, Starters, Yeast and Cake Pans Baker's percentages measure everything against flour, not dough. How that settles hydration, starter math, pizza styles, yeast swaps and cake pan scaling. Sep 30, 2026 · uses Pizza Dough Calculator, Sourdough Calculator, Bread Hydration Calculator +2
- Turkey Thaw Time and Safe Temperatures: The USDA Math, Worked Out USDA says 24 hours of fridge time per 4–5 lb, so a 20 lb turkey for Thanksgiving goes in the fridge by Saturday. The thaw, roast and 165 °F rules, worked out. Sep 30, 2026 · uses Rice to Water Ratio Calculator, Turkey Thaw Time Calculator, Meat Cooking Time Calculator +1
- Coffee to Water Ratio by Brew Method (and Why It's by Weight) The SCA's 55 g per kg of water is about 1:18. Here are the ratio ranges for pour-over, French press, AeroPress, cold brew and espresso, and why grams beat scoops. Sep 30, 2026 · uses Coffee Ratio Calculator, Rice to Water Ratio Calculator, Cocktail Dilution Calculator
- Is Math.random() Random Enough? (Usually No) Math.random vs crypto.getRandomValues: why V8 output is predictable from a few samples, how modulo bias loads a dice roll, and the JavaScript shuffle bug. Sep 5, 2026 · uses Dice Roller, Coin Flip, Secret Santa Generator
- What BMI Can and Can't Tell You The BMI formula and its 1830s origin, the adult cut-points, why children use percentiles, and what waist-to-height ratio adds. Worked in metric and US units. Oct 6, 2026 · uses BMI Calculator, Calorie Calculator
- What Do I Need on My Final? The Formula, Plus Weighted GPA Math The final exam formula is (target − current × (1 − w)) ÷ w. Worked examples, why weights must add to 100, how dropped scores shift it, and how GPA points work. Sep 30, 2026 · uses GPA Calculator, Grade Calculator
- Dimensional Weight: What the 139 Divisor Actually Means Billable weight is the larger of actual weight and L×W×H ÷ 139. What 139 means as a density, who uses 166 or 5,000, USPS's July 2026 switch, and pallets. Sep 28, 2026 · uses Shipping Dimensional Weight Calculator, Pallet Loading Calculator
- How to Total a Timesheet with Breaks and Overnight Shifts (and Convert 7:45 to 7.75 Hours) Step-by-step timesheet math: subtract unpaid breaks, handle shifts that cross midnight, apply daily or 40-hour overtime, and convert minutes to decimal hours. Oct 16, 2026 · uses Time Card Calculator
- How to Write a Check Amount in Words (With Cents, Zeros, and Cents Under $1) Dollars in words, 'and', then cents over 100: $123.45 is 'One hundred twenty-three and 45/100'. Six examples, plus what wins when words and numbers disagree. Oct 15, 2026 · uses Time Card Calculator
- Secret Santa Without a Hat: Derangements, Exclusions, Private Links Drawing names from a hat fails about 63% of the time with 5+ people. The math of derangements, when couple exclusions make a draw impossible, and how reveal links work. Oct 15, 2026 · uses Secret Santa Generator
- How Long Does a Propane Tank Last? The BTU Math, Worked Out A 20 lb tank holds about 4.7 gallons, or roughly 431,600 BTU. Divide by the burner's BTU/h to get hours. Worked examples for grills, heaters, generators and furnaces. Sep 29, 2026 · uses Propane Usage Calculator
- Domain Age: What RDAP Actually Tells You (and What It Can't) Domain age is one RDAP event: the current registration's creation date. Why some registries omit it, why re-registration resets it, and why Google doesn't rank on it. Sep 28, 2026 · uses Age Calculator