Free tools
Interactive calculators and labs
Every tool below is a live model you can drag, tune, and learn from — no sign-up, nothing leaves your browser. Each one comes from a full VibeTutor course where the idea is taught properly.
Writing & speaking
Design & accessibility
Health & habits
- Sleep Cycle Calculator Pick a wake-up time your brain agrees with — between cycles, not inside one.
- Heart Rate Zone Calculator Find the zone before you train — and check it with the talk test.
- Breathing Exercise Timer A paced circle for box breathing, 4-7-8, and longer-exhale calm.
- 1% Better Every Day Calculator The famous 37.8× curve — and its quiet warning about daily decay.
Money
Home & everyday safety
- Password Strength Visualizer See how length and variety multiply cracking time — without typing a real password.
- Stopping Distance Calculator Thinking distance plus braking distance — and why speed matters more than it feels.
- Heat Loss Calculator Q = U·A·ΔT — watch single glazing leak and insulation pay for itself.
- Carbon Footprint Estimator Three habits in tons of CO₂ — find your biggest lever before choosing your swaps.
Science & space
- Moon Phase Viewer Scrub through the 29.5-day lunar cycle and read tonight's illumination.
- Wind Chill Calculator The Environment Canada formula for what the cold actually feels like.
- Margin of Error Calculator Certainty is priced in square roots — see what a bigger sample actually buys.
- Projectile Motion Simulator Speed and angle in, arc out — with range, peak height, and flight time live.
- Telescope Magnification Calculator Scope focal length ÷ eyepiece = power — and the aperture sets the honest limit.
Music & audio
- Online Metronome with Subdivisions Set a tempo, choose a subdivision, and feel the grid every musician counts on.
- Tone Generator (Hz to Note) Slide a frequency, see the wave compress, and hear the nearest musical note name itself.
- Piano Chord Finder Pick a root and quality — the keyboard lights the notes and plays the sound.
Kitchen & baking
- Coffee Ratio Calculator Espresso 1:2, pour-over 1:16 — dial any dose to its method's ratio by weight.
- Dough Hydration Calculator Water divided by flour — the single number that most changes how dough behaves.
- Proofing Time Estimator Cooler kitchen, slower dough — plan the rise around your room temperature.
- Salt Percentage Calculator Season by weight — 1% for dishes, 2% for bread and quick brines.
- Interactive Candy Temperature Chart Thread to hard crack — slide the thermometer and see what each stage makes.
- Frosting & Ganache Ratio Calculator American, Swiss, pouring ganache, truffle ganache — scaled to your batch in grams.
Garden & growing
- Plant Spacing Calculator Set the bed, set the spacing, and see exactly how many plants honestly fit.
- Seed Starting Calculator Count backward from your frost date — sowing dates are subtraction, not folklore.
- Compost Ratio Calculator Balance greens and browns until the pile can heat and breathe.
- DLI Calculator (Daily Light Integral) Intensity × hours × 0.0036 — the light number plants actually live on.
- Rainwater Harvest Calculator Roof area × rainfall × 0.9 — see how fast a real roof fills a real tank.