Sleep Cycle and Optimal Bedtime Calculator
Calculates optimal bedtimes based on 90-minute sleep cycles. Waking at the end of a cycle (90, 180, 270, 360, 450, 540 m...
Tipping, cooking, travel, and other useful little tools.
The calculators that come up in day-to-day life — tip splitting, cooking conversions, fuel costs, and trip planning.
Calculates optimal bedtimes based on 90-minute sleep cycles. Waking at the end of a cycle (90, 180, 270, 360, 450, 540 m...
Calculates approximate AQI from PM2.5 concentration and shows ratios to WHO and US EPA guidelines. Outputs a simplified...
Estimates food shelf life at a given storage temperature relative to a reference temperature using the Q10 temperature c...
Estimates how often to water a plant and how much water to use from pot diameter, soil drainage, and light conditions.
Calculates braking distance d = v²/(2a), total stopping distance (braking + reaction distance = v × 0.75 s), where a ≈ 6...
Estimates the time to sunburn (minutes) from UV index and skin type (Minimal Erythemal Dose). Enter SPF to calculate pro...
Calculates the unit price (per gram, ml, or item) for two grocery products to identify the better value purchase.
Estimates calories burned from step count and body weight. Uses the general rule that a 70 kg person burns approximately...
Calculates total calories from macronutrients (protein, carbohydrates, fat) and shows percentage contribution of each ma...
Converts an amount at a given exchange rate, subtracts a percentage fee, and shows the received amount, fee paid, and ef...
Estimates transfer time = file size (bits) / transfer speed (bps). Reference speeds: USB 2.0 = 480 Mbit/s, USB 3.0 = 5 G...
Calculates alcohol units in any drink from volume and ABV, and compares weekly total against recommended limits (UK guid...
Split a restaurant bill across any number of people, including the tip — see the per-person tip and total at a glance.