1108 calculator questions, answered.
Common questions that have a single right answer — math, finance, conversions, home, health, automotive. One question per page, the answer on top, the formula below.
What this section is
One URL per question. Each page renders the answer in a black panel at the top — no scrolling past intros, no ads above the fold. Below the answer: the formula, a step-by-step walkthrough, and a live calculator widget so you can change the inputs without leaving the page.
How we wrote them
Every answer is computed at build time from the same engine that powers the interactive calculators on this site — no hand-typed numbers, no AI hallucinations. Conversion factors use SI canonical values; finance pages run standard amortization.
By category
- Conversions808answers · 73% of total
- Finance80answers · 7% of total
- Automotive80answers · 7% of total
- Home50answers · 5% of total
- Health35answers · 3% of total
- Math20answers · 2% of total
Scroll down for the alphabetised list of every cluster, or click a category heading below to jump to that cluster's dedicated topic page with all its answers.
Automotive - tire pressure70 answers
- What tire pressure should I use for a Audi A3 for motorway driving?
- What tire pressure should I use for a Audi A3 for street driving?
- What tire pressure should I use for a Audi A3 for track day?
- What tire pressure should I use for a Audi A3 for winter driving?
- What tire pressure should I use for a BMW 320d for motorway driving?
- What tire pressure should I use for a BMW 320d for street driving?
- What tire pressure should I use for a BMW 320d for track day?
- What tire pressure should I use for a BMW 320d for winter driving?
- +62 more →
Automotive - tire size10 answers
- What is the difference between 185/60R15 and 195/50R15 tires?
- What is the difference between 195/55R16 and 205/50R17 tires?
- What is the difference between 205/55R16 and 225/45R17 tires?
- What is the difference between 215/45R17 and 225/40R18 tires?
- What is the difference between 225/40R18 and 235/35R19 tires?
- What is the difference between 225/45R17 and 235/40R18 tires?
- What is the difference between 235/35R19 and 245/35R19 tires?
- What is the difference between 245/45R18 and 255/40R19 tires?
- +2 more →
Business - hourly rate10 answers
- How much should I charge for 10 hours at €15 per hour?
- How much should I charge for 100 hours at €45 per hour?
- How much should I charge for 12 hours at €35 per hour?
- How much should I charge for 120 hours at €30 per hour?
- How much should I charge for 160 hours at €18 per hour?
- How much should I charge for 20 hours at €25 per hour?
- How much should I charge for 37.5 hours at €12 per hour?
- How much should I charge for 40 hours at €20 per hour?
- +2 more →
Business - VAT10 answers
- What is the price including 10% VAT on €300?
- What is the price including 13% VAT on €75?
- What is the price including 19% VAT on €80?
- What is the price including 20% VAT on €500?
- What is the price including 21% VAT on €1000?
- What is the price including 23% VAT on €120?
- What is the price including 24% VAT on €100?
- What is the price including 24% VAT on €1000?
- +2 more →
Conversion - bar to PSI66 answers
Conversion - Celsius to Fahrenheit63 answers
Conversion - cm to inches21 answers
Conversion - Fahrenheit to Celsius47 answers
Conversion - feet to meters16 answers
Conversion - gallons to litres14 answers
Conversion - hp to kW42 answers
- How many kilowatts is 100 horsepower?
- How many kilowatts is 150 horsepower?
- How many kilowatts is 200 horsepower?
- How many kilowatts is 250 horsepower?
- How many kilowatts is 300 horsepower?
- How many kilowatts is 500 horsepower?
- How many kilowatts is 50 horsepower?
- How many kilowatts is 60 horsepower?
- +34 more →
Conversion - inches to cm23 answers
Conversion - kg to lb21 answers
Conversion - km to miles18 answers
Conversion - km/h to mph30 answers
Conversion - kW to hp36 answers
Conversion - lb to kg23 answers
Conversion - lb-ft to Nm18 answers
Conversion - litres to gallons17 answers
Conversion - meters to feet30 answers
Conversion - miles to km15 answers
Conversion - mph to km/h40 answers
Conversion - Nm to lb-ft25 answers
Conversion - percentage of value162 answers
Conversion - PSI to bar81 answers
Cooking - grams to ounces5 answers
Finance - loan payment80 answers
- What is the monthly payment on a €10,000 loan at 12% for 10 years?
- What is the monthly payment on a €10,000 loan at 12% for 20 years?
- What is the monthly payment on a €10,000 loan at 12% for 3 years?
- What is the monthly payment on a €10,000 loan at 12% for 30 years?
- What is the monthly payment on a €10,000 loan at 12% for 5 years?
- What is the monthly payment on a €10,000 loan at 3% for 10 years?
- What is the monthly payment on a €10,000 loan at 3% for 20 years?
- What is the monthly payment on a €10,000 loan at 3% for 3 years?
- +72 more →
Health - BMI10 answers
- What is my BMI if I weigh 100 kg and I am 185 cm tall?
- What is my BMI if I weigh 55 kg and I am 160 cm tall?
- What is my BMI if I weigh 60 kg and I am 165 cm tall?
- What is my BMI if I weigh 68 kg and I am 172 cm tall?
- What is my BMI if I weigh 70 kg and I am 170 cm tall?
- What is my BMI if I weigh 75 kg and I am 178 cm tall?
- What is my BMI if I weigh 80 kg and I am 180 cm tall?
- What is my BMI if I weigh 82 kg and I am 180 cm tall?
- +2 more →
Health - calorie deficit5 answers
Health - macros10 answers
- How much protein should I eat per day if I weigh 100 kg?
- How much protein should I eat per day if I weigh 110 kg?
- How much protein should I eat per day if I weigh 120 kg?
- How much protein should I eat per day if I weigh 60 kg?
- How much protein should I eat per day if I weigh 65 kg?
- How much protein should I eat per day if I weigh 70 kg?
- How much protein should I eat per day if I weigh 75 kg?
- How much protein should I eat per day if I weigh 80 kg?
- +2 more →
Health - TDEE10 answers
- What is my TDEE if I am a 22-year-old female, 168 cm, 58 kg, and active?
- What is my TDEE if I am a 25-year-old male, 185 cm, 78 kg, and active?
- What is my TDEE if I am a 28-year-old female, 165 cm, 60 kg, and lightly active?
- What is my TDEE if I am a 30-year-old male, 180 cm, 82 kg, and moderately active?
- What is my TDEE if I am a 31-year-old female, 175 cm, 72 kg, and moderately active?
- What is my TDEE if I am a 33-year-old male, 172 cm, 75 kg, and very active?
- What is my TDEE if I am a 35-year-old female, 170 cm, 70 kg, and very active?
- What is my TDEE if I am a 40-year-old male, 175 cm, 90 kg, and sedentary?
- +2 more →
Home - area10 answers
- How many square meters is a room that is 10 m by 5 m?
- How many square meters is a room that is 12 m by 6 m?
- How many square meters is a room that is 15 m by 8 m?
- How many square meters is a room that is 2.5 m by 3 m?
- How many square meters is a room that is 3.5 m by 4.5 m?
- How many square meters is a room that is 3 m by 4 m?
- How many square meters is a room that is 4 m by 5 m?
- How many square meters is a room that is 5 m by 6 m?
- +2 more →
Home - concrete10 answers
- How many cubic meters of concrete do I need for 1 m³?
- How many cubic meters of concrete do I need for 10 m³?
- How many cubic meters of concrete do I need for 15 m³?
- How many cubic meters of concrete do I need for 2 m³?
- How many cubic meters of concrete do I need for 20 m³?
- How many cubic meters of concrete do I need for 25 m³?
- How many cubic meters of concrete do I need for 3 m³?
- How many cubic meters of concrete do I need for 30 m³?
- +2 more →
Home - materials10 answers
- How many meters of fence do I need for a 10 m side?
- How many meters of fence do I need for a 100 m side?
- How many meters of fence do I need for a 15 m side?
- How many meters of fence do I need for a 20 m side?
- How many meters of fence do I need for a 25 m side?
- How many meters of fence do I need for a 30 m side?
- How many meters of fence do I need for a 40 m side?
- How many meters of fence do I need for a 5 m side?
- +2 more →
Home - paint10 answers
- How much paint do I need for a 10 m² room?
- How much paint do I need for a 100 m² room?
- How much paint do I need for a 120 m² room?
- How much paint do I need for a 15 m² room?
- How much paint do I need for a 20 m² room?
- How much paint do I need for a 25 m² room?
- How much paint do I need for a 30 m² room?
- How much paint do I need for a 40 m² room?
- +2 more →
Home - tiles10 answers
Math - percentage10 answers
Math - percentage change10 answers
- What is the percentage change from 100 to 120?
- What is the percentage change from 1200 to 900?
- What is the percentage change from 1500 to 1800?
- What is the percentage change from 250 to 200?
- What is the percentage change from 35 to 28?
- What is the percentage change from 400 to 350?
- What is the percentage change from 60 to 45?
- What is the percentage change from 75 to 105?
- +2 more →
Shopping - discount10 answers
- What is the final price of €100 after a 20% discount?
- What is the final price of €129 after a 25% discount?
- What is the final price of €200 after a 40% discount?
- What is the final price of €250 after a 15% discount?
- What is the final price of €350 after a 18% discount?
- What is the final price of €49 after a 10% discount?
- What is the final price of €500 after a 30% discount?
- What is the final price of €60 after a 5% discount?
- +2 more →