Free calculators for health, home, garden & craft
No sign-up, no apps, no clutter. Pick a calculator, enter your numbers, and get an answer in seconds — every tool also shows the formula behind the result so you can double-check the math yourself.
Health & fitness
BMI Calculator
Body mass index, WHO category and your healthy weight range.
Calorie Calculator
Daily calories to maintain, lose or gain weight (BMR & TDEE).
Macro Calculator
Protein, carb and fat grams for your calorie target and goal.
Water Intake Calculator
How much water to drink per day for your weight and activity.
Due Date Calculator
Estimated due date, current pregnancy week and trimester.
Ovulation Calculator
Predicted ovulation day, fertile window and next period by cycle length.
Pregnancy Weight Gain Calculator
IOM gain range, weekly rate and week-by-week target from your pre-pregnancy BMI.
One Rep Max Calculator
Estimate your 1RM and training percentages from any set.
Sleep Cycle Calculator
Best bedtimes and wake times based on 90-minute cycles.
Ideal Weight Calculator
Devine & Hamwi formulas plus your healthy BMI range.
Body Fat Calculator
Navy tape method: body fat % from three measurements.
Running Pace Calculator
Pace per km/mile, speed, and race time predictions.
Heart Rate Zone Calculator
Your five training zones by the Karvonen method.
Protein Calculator
Daily protein grams by body weight and goal.
Home, garden & craft
Mulch Calculator
Cubic yards, cubic feet and bags of mulch for any bed size and depth.
Gravel Calculator
How much gravel you need in cubic yards and tons, by area and depth.
Topsoil Calculator
Topsoil volume in yards plus tons and bag counts for lawns and beds.
Paint Calculator
Gallons of paint for a room, with doors and windows subtracted.
Grass Seed Calculator
Pounds of seed for your lawn size, by grass type and seeding method.
Raised Bed Soil Calculator
Soil volume and bag counts for any raised bed or planter size.
Pond Liner Calculator
Liner size that covers your pond's length, width, depth and overlap.
Sourdough Hydration Calculator
True dough hydration percentage, including your starter's water.
Candle Wax Calculator
Wax and fragrance oil amounts per container, by wax type and load.
Aquarium Heater Calculator
Heater wattage for your tank size and the temperature rise you need.
Firewood Cord Calculator
Full cords and face cords in any stack, with cost per cord.
Epoxy Resin Calculator
Mixed volume, resin/hardener split by ratio, kits to buy and cost per square foot.
Why CalcNest?
Most calculator sites hide the math. We do the opposite: every tool on CalcNest shows the exact formula it uses, the assumptions behind it (bag sizes, coverage rates, densities), and a short FAQ so you can sanity-check the answer for your own project. If a number looks off, you'll know exactly why.
We add new calculators every week. If there's a calculator you wish existed, tell us — reader requests go straight to the top of the queue.