How Much Do You Really Need?
Real numbers instead of rough rules of thumb – for food, drinks, home projects and daily life.
Grilling, cheese and drinks: an overview of the topics that keep coming up when you host at home.
Water, sleep, sun, caffeine and life with small kids. An overview of topics that keep coming up in everyday life.
All renovation and DIY material calculators in one place – paint, wallpaper. Browse by project type to find the right tool.
All money calculators in one place – savings, workplace costs, daily-life math. Browse by topic to find the right tool.
All carbon and consumption calculators in one place – digital impact, streaming, cloud and AI. Browse by topic to find the right tool.
All outdoor and event-planning calculators in one place – festival packing, camping, multi-day trip math. Browse by activity to find the right tool.
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🍳 Kitchen & Home (6)
Grilling Calculator
How much meat per person for a BBQ? For 4–30 guests, split by men, women, teens, and kids — with sides factor and vegetarian option.
🧀Raclette Calculator
How much raclette cheese, potatoes and sides per guest — calibrated for 2–4 hour evenings where consumption ramps up after round one.
🍹Party Drinks Calculator
Plan beer, wine, ice and water for 10–100 guests — built from how guests actually drink, including the first-hour spike and ice melt curve most lists ignore.
🍹Aperol Spritz Calculator
How many bottles of Aperol and Prosecco? You need more Prosecco than Aperol (3:2:1) — the calculator gives the right split for 4–50 guests.
🌿Hugo Spritz Calculator
Calculate how much Prosecco, elderflower syrup, and soda water you need for your party.
🧀Cheese Board Calculator
Calculate the perfect amount of cheese for your party – with variety breakdown and pairing suggestions.
💪 Health & Fitness (6)
Daily Water Intake Calculator
Calculate exactly how much water you need per day based on your weight, activity level, and climate – with bottle count and hike recommendation.
☀️Sunscreen Calculator
Calculate how long your sunscreen protects you. Enter skin type + SPF → get your protection time & reapply reminder instantly.
🏖️Sunscreen Vacation Calculator
How much sunscreen to pack — in bottles, not guesses. Built on realistic application rates and the adherence gap most travellers run into.
😴Sleep Calculator
Calculate your ideal bedtime or wake-up time based on 90-minute sleep cycles. Wake up refreshed instead of groggy – try our free sleep calculator!
☕Caffeine Half-Life Calculator
When the caffeine in your body drops below the 50 mg sleep threshold — built on the 5 h half-life and the time of your last drink, the strongest sleep lever.
👶Diaper Calculator
Stage-based diaper counts from newborn to potty training — daily use, size by weight, bulk stock and brand sizing notes.
🏗️ Building & Renovation (2)
💰 Finance & Everyday (2)
Compound Interest Calculator
Calculate compound interest with monthly contributions, flexible compounding frequency and a visual growth chart.
⏱️Meeting Cost Calculator
Find out what your meetings actually cost. Enter attendees, salary, and duration to instantly calculate the real cost of any meeting.
🌱 Sustainability (1)
🎪 Outdoor (1)
The Gap Between Gut Feeling and Professional Advice
Most decisions live on one of two safe shores. On one side, the trivial daily choices — how much coffee, what's for dinner, does the jacket need to come along today. Intuition decides, nobody writes a plan. On the other side, the big life decisions — buying a house, surgery, choosing a college, the full tax return. There are professionals for those: realtors, doctors, attorneys, advisors. Both shores are well served.
Between them lies a wide gap. Questions that are too complex for intuition but too small for a professional appointment: how much paint for a 13×16 ft (4×5 m) room, how many bottles of sunscreen for ten days at the beach with two kids, what $300 a month in an ETF actually becomes after 30 years, how much meat to grill for 14 people including three kids and two vegetarians. Nobody calls a CPA over a $300 monthly savings rate. Nobody hires a contractor for one living-room wall. Intuition reliably lands 30% off, though — and 30% off means the wall ends up two-tone, the family burns on day six, the retirement number lands $200,000 short, three days of leftovers from the cookout. HowMuchTools is built for exactly this gap.
Why This Gap Is Hard to Close
Three structural reasons the middle band between intuition and professional advice rarely gets covered properly:
- The consulting market doesn't pencil out. A CPA hour costs $150 to $400. A sunscreen-quantity consultation for a ten-day Mediterranean trip would cost the same — nobody pays that. The advisory industry consistently ignores the middle band, and the unit economics are why: the per-question revenue doesn't match the stakes of the underlying decision.
- The app industry solves a different problem. Habit trackers, daily apps, streak-based tools are built around daily repetition. A wall-paint quantity isn't a habit — it needs an answer once a year, not 365 push notifications. The app logic doesn't fit the frequency.
- Universal rules of thumb are too coarse. "Drink 2 liters of water a day," "sleep 8 hours," "SPF 50 is always enough," "save 10% of income" — every rule is approximately right on average and almost always off for any individual. The gap demands numbers that account for the personal: weight, skin type, climate, group size, time horizon.
This site tries to close the gap with tools whose design matches the frequency and stakes: no account, no tracker, no daily reminders. One question, one answer, then gone until the question comes back — typically a few times a year per topic.
The Six Topic Areas Where the Gap Lives
Within the gap, questions cluster into six domains. Each has its own topic hub with framing, sub-hubs, and tools:
Kitchen & Home covers the hosting gap — the questions that show up when a group is expected and "rough guess" produces either too little (panic on the way to the grocery store) or way too much (three days of leftovers). Grilling, cheese nights, party drinks. Not everyday cooking, but the few times a year when 12, 20, or 30 people are coming and it's no longer fine to skip the math.
Health & Fitness handles the body-aware gap — hydration, sleep, sun exposure, caffeine timing, the first year with a baby. No diagnosis, no medical advice. The everyday calibration questions where blanket rules-of-thumb are too coarse and a doctor's visit is overkill. The middle layer between "I'm doing fine" and "I need a clinic appointment."
Building & DIY covers the material-estimation gap for renovations — when paint cans and wallpaper rolls have to be bought in advance and "two rolls short on Sunday afternoon" is the expensive failure mode. Professionals (painters, paperhangers) do this routinely; DIYers face the gap because the coverage label on the can was measured under lab conditions and the real wall behaves differently.
Finance & Daily Life sits at the intersection of money math and time math. Compound interest over decades, meeting costs that look trivial per occurrence and accumulate to entire workdays per year, inflation as the silent shrinkage on the savings account. A CPA doesn't run this math — these questions are too small for a billable hour. But intuition leaves them just as invisible.
Sustainability makes the invisible visible inside the gap — particularly for digital habits, where the carbon, water, and energy footprint has no rule of thumb and nobody hires a climate consultant for it. Streaming, cloud storage, AI use running in the background of a modern digital life.
Outdoor handles the planning gap for multi-day outdoor events where everyday apartment rules don't apply — festivals, camping, multi-day hikes. Nobody hires a festival-logistics consultant, but intuition is reliably 50% off on toilet paper, sunscreen, water, and powerbanks once every category has to scale at once.
When the Gap Tips Into Professional Territory
Not every question that starts in the middle stays there. There are clear transitions where the gap ends and a professional appointment becomes the right next step. Every topic hub addresses these thresholds explicitly, but they deserve a place on the homepage:
- Sleep: Calibrating bedtime against 90-minute cycles = middle band. Six hours of actual sleep despite eight hours in bed over weeks, with persistent daytime exhaustion = primary care or sleep clinic.
- Hydration: Afternoon focus dip, mild concentration issues = middle band. Persistent thirst despite normal intake plus increased urination = primary care (possible diabetes signal).
- Skin changes in summer: Sunburn prevention through SPF choice and quantity = middle band. A changing mole, asymmetric edges or uneven color = dermatologist.
- Renovation: Wall paint and wallpaper = middle band. Load-bearing walls, structural changes, electrical, and plumbing = licensed professional — and in many jurisdictions, legally required for electrical and gas work.
- Finance: Calibrating savings rate, compound interest planning, meeting cost analysis = middle band. Estate planning, self-employment bookkeeping, international tax = CPA or financial planner. Major retirement planning with a specific drawdown phase = fee-only advisor.
- Parenting topics: Diaper planning, Wonder Weeks, parental sleep deprivation routines = middle band. Persistent postpartum depressive symptoms, attachment difficulties, behavioral concerns = midwife, pediatrician, or PSI helpline.
The site covers the middle band — but it knows where the band ends, and says so clearly. That's the decisive difference from a pure calculator collection, which would feed every question into the same math engine without distinguishing.
Hub, Sub-Hub, or Tool — Three Depths Inside the Gap
Inside the middle band, the site is built in three layers. Each one answers a different size of gap-question:
- Topic hubs (Kitchen, Health, Building, Finance, Sustainability, Outdoor) are the broad framing layer. They explain what kinds of gap-questions cluster in this domain and where the boundary to professional territory sits. Useful when the question is general ("we're planning a beach week") or when it's unclear whether the question is even still in the middle band.
- Sub-hubs (Grilling, Hydration, Paint, Savings, and so on) go one layer deeper into a sub-domain. They cover the operational knowledge that surrounds the calculation — what makes paint coverage different from wallpaper coverage, why hydration timing matters as much as quantity, how compounding behaves over a 40-year horizon. Useful when the topic is clear but the logic behind it isn't yet.
- Individual tools are the number-producing layer. Enter the inputs, get a concrete answer. Useful when the question is precisely defined and only the number is missing.
Shortest path: scroll up and use the search field for a tool name, or the category chips to filter by topic. Longer path: open a topic hub, read the framing, navigate into the right sub-hub, then open the tool. Both arrive at the same number — but the second path is the one to take when the question isn't yet sharply defined, or when the boundary to professional territory might be relevant.