A watched pot never boils; an unwatched 3kW kettle takes about four minutes and roughly 11p of electricity. Between those two facts lies this calculator: the honest thermodynamics of waiting, and the strange physics of what your hands do in the meantime.
The boil-time half is pure energy balance: heating water takes 4.186 joules per gram per degree, divided by your appliance’s real delivered wattage and efficiency (electric kettles ~85%, induction ~85%, gas burners a shameful ~40%). Homebrewers know the far end of this curve — bringing 7 gallons of wort to a boil on an 1800W induction plate takes over an hour and a half.
The impatience half models the documented human response: fidgeting. Following the source framework, we treat wire-bending — the classic idle deformation of a paperclip or twist-tie — as a thermal-mechanical relief channel: each bend does work, dissipates heat along the wire, and converts wait-time into somatic relief. Enter your setup; get your true boil time, cost per boil, and your Somatic Impatience Relief Factor.
The formula
m·c·ΔT- Water mass × specific heat (4186 J/kg·K) × temperature rise
P·η- Appliance power × thermal efficiency (kettle ≈ 0.85, gas ≈ 0.40)
f_bend- Your fidget frequency — wire bends per minute while waiting
R_wire- Thermal resistance of the fidget wire: length / (conductivity × cross-section)
SIRF- Somatic Impatience Relief Factor — accumulated relief over the wait
How it works, step by step
- Enter water volume and starting temperature (tap water is typically 12–18°C).
- Pick your appliance — wattage and efficiency set the true energy delivery rate.
- Enter your electricity price to get cost per boil and per annual habit.
- Rate your impatience and fidget style; the model computes relief accumulated across the wait.
- Compare appliances: the same litre boils in 2:56 on a 3kW kettle and 13+ minutes in a covered pan on gas.
Worked examples
The office tea run
0.5L at 15°C in a 3kW kettle: 1m 10s, ~0.5¢ per boil. Score band: Flash boil — the model notes your fidget window is too short for meaningful relief and recommends simply staring out a window like a Victorian.
The homebrew boil-up
26.5L (7 gal) of wort on an 1800W induction hob: ~103 minutes to boiling, ~$0.86 in electricity, felt duration near three hours at impatience 8/10. With fidget intensity 7, the brewer accumulates 1,290+ wire bends — SIRF hits 90/100. Energy balance is crueler than brewing folklore’s 75-minute legend.
How to read your score
Frequently asked questions
How long does it really take to boil water?
Energy balance gives exact answers: one litre from 15°C needs ~356 kJ; delivered by a 3kW kettle at 85% efficiency that is ~2 minutes 20 seconds. Doubling volume doubles time; halving wattage doubles it again. Gas feels faster but wastes ~60% of its heat around the pan.
Does a lid actually make water boil faster?
Yes — typically 15–25% faster on a stovetop by suppressing evaporative and convective losses. (Kettles are already sealed, which is part of why they win.) Salt, by contrast, raises the boiling point trivially: ~0.17°C for a teaspoon per litre. Add it for flavor, not speed.
Why does watched water feel slower?
Attention dilates perceived duration — the calculator’s felt-duration output applies your impatience factor to model it. The folk remedy is mechanistically sound: leaving the kitchen removes the sampling loop that makes waiting feel long.
Is an electric kettle cheaper than the stove?
Per boil, almost always: a kettle converts ~85% of electricity into water heat versus ~70–75% for an electric coil and ~40% for gas (though gas energy is often cheaper per kWh — the calculator’s cost output lets you compare directly with your local prices).
What is the wire-bending thing about?
The source framework models idle fidgeting — bending a paperclip or twist-tie while waiting — as a thermal-mechanical relief channel: each bend does plastic work, heats the wire along its thermal resistance, and discharges restlessness. The SIRF score is a playful formalization of a real phenomenon (fidgeting measurably regulates arousal during enforced waits).
Does this store my inputs?
No — all thermodynamics runs locally in your browser.
Reference: boil times & energy costs by method
| Method | Typical time | Energy used | Cost @ $0.17/kWh |
|---|---|---|---|
| Electric kettle (3kW) | ~2.2 min | ~0.11 kWh | ~1.9¢ |
| Electric kettle (1.5kW) | ~4.4 min | ~0.12 kWh | ~2.0¢ |
| Induction hob (covered pot) | ~4 min | ~0.13 kWh | ~2.2¢ |
| Gas hob (covered pot) | ~5 min | ~0.22 kWh gas | ~1.5¢ (gas rates) |
| Electric coil hob (covered) | ~7 min | ~0.18 kWh | ~3.1¢ |
| Microwave (1L, not ideal) | ~8 min | ~0.15 kWh | ~2.6¢ |
Kettles win on speed and efficiency (~80–90% of energy reaches the water vs ~40–55% on hobs). A lid cuts hob boil time by ~25%.