Vertical Speed Unit Converter (m/s ↔ ft/min ↔ km/h ↔ knots)
Vertical speed is the rate of altitude change, measured in SI by **metres per second (m/s)**. Different fields use different units: **aviation VSI** displays **ft/min** (feet per minute, fpm); **mountaineering and trail-running** quote **m/h** or **m/min** (this tool shows m/s and km/h); **scuba ascent rate** uses **m/min** (NOAA ≤ 9 m/min ≈ 0.15 m/s); **marine and aerospace altitude change** sometimes uses **knots** (1 knot vertical = 1.944 m/s — uncommon vertically, common horizontally); **elevator and gravity engineering** uses **ft/s** or **m/s**. This tool converts instantly across all five and shows the full table side-by-side.
Enter a valid number (positive, negative or zero).
Live conversion table
Reference: 1 m/s = 196.85 ft/min ≈ 1.944 knots ≈ 3.6 km/h. Aviation instruments (VSI) read in ft/min, mountaineering uses m/h, scuba ascent-rate uses m/min.
- m/s Science, SI; sports (high-diving, skydiver terminal velocity).
- ft/min Aviation VSI / vertical-speed indicator, elevator specs.
- ft/s Imperial gravity / mechanics (free-fall g ≈ 32.2 ft/s²).
- km/h Everyday vehicles; ski / cycling downhill speed.
- kn Marine and aviation cruise speed (1 nautical mile = 1852 m).
—
Formula
Reference: 1 m/s (SI). Exact conversion factors (each unit → m/s): 1 m/s = 1 m/s 1 ft/min = 0.3048 / 60 m/s = 0.00508 m/s (exact; international foot) 1 ft/s = 0.3048 m/s (exact) 1 km/h = 1000 / 3600 m/s ≈ 0.277 78 m/s (exact) 1 knot = 1852 / 3600 m/s ≈ 0.514 44 m/s (exact; nautical mile = 1852 m, ICAO) Rules of thumb: 1 m/s = 196.85 ft/min = 3.6 km/h = 1.944 knots = 3.281 ft/s 1 000 ft/min = 5.08 m/s = 18.29 km/h = 9.87 knots
- · **Aviation VSI reads in ft/min, not m/s** — every ICAO-standard cockpit Vertical Speed Indicator (VSI) reads ft/min, regardless of metric or imperial country. **Typical values**: (a) commercial jet climb 1 500–2 500 ft/min (7.6–12.7 m/s); (b) Cessna takeoff 700 ft/min (3.6 m/s); (c) standard approach descent −500 ft/min (−2.54 m/s); (d) 3° ILS glide-path at 140 kt ≈ −740 ft/min; (e) Vy (best rate of climb) is a *speed*, not a VSI reading.
- · **Scuba ascent-rate limits** — (a) NOAA / US Navy (post-1988) ≤ 30 ft/min = 9 m/min ≈ 0.15 m/s (DCS avoidance); (b) PADI (post-1996) ≤ 18 m/min ≈ 0.3 m/s; (c) DAN (post-2010) reiterates "slower is better"; deeper than 30 m ≤ 10 m/min. **Conversions**: 18 m/min = 59 ft/min; 30 ft/min = 9.14 m/min. **Do not use aviation ft/min figures for diving** — they are 60× larger.
- · **Mountaineering and trail-running quote m/h or VAM** — (a) **m/h (vertical metres gained per hour)** is the climbing rate; 3 000 m/h ≈ 0.83 m/s is world-class. (b) **VAM** (Velocità Ascensionale Media) is the cycling climbing metric: 1 800 VAM ≈ pro peloton average, 2 000+ ≈ Tour de France stage-winner at the front of the climb. **Conversions**: 1 m/h = 0.000 28 m/s; 1 800 m/h = 0.5 m/s = 100 ft/min.
- · **Elevator specs use m/s or ft/min** — China, Japan, Taiwan, Korea quote m/s; US, UK, Canada quote ft/min. **Typical**: (a) residential lift 1.0–2.0 m/s (200–400 ft/min); (b) mid-rise commercial 2.5–5.0 m/s; (c) super-tall 8–10 m/s (Burj Khalifa double-deck cab 18 m/s = 3 543 ft/min); (d) Otis Skyrise test record 1 200 m/min = 20 m/s.
- · **Knots = nautical miles per hour** — 1 nautical mile (ICAO/IMO) = **exactly 1 852 m**, so 1 knot = 1852 / 3600 m/s ≈ 0.514 444 m/s. **Note**: knots are almost always *horizontal* (ship speed, wind, IAS / TAS). Vertical knots are rare but well-defined (1 knot vertical = 101.27 ft/min). The tool supports it for completeness.
- · **Sources**: (1) NIST SP 811 (2008), App. B exact-conversion table; (2) BIPM SI Brochure, 9th ed. (2019), §2.3.4 (m/s definition); (3) ICAO Annex 5 *Units of Measurement to be Used in Air and Ground Operations* — 1 nm = 1852 m; (4) NOAA Diving Manual (6th ed., 2017); PADI Open Water Diver Manual (2022); DAN Annual Diving Report — ascent-rate guidance; (5) ISO 80000-3:2019 *Quantities and units — Space and time*.
Frequently asked
My aircraft VSI shows 1 500 ft/min climb — what is that in m/s?
**Short answer**: 1 500 ft/min ≈ **7.62 m/s = 27.4 km/h**. **Working**: 1 500 × 0.3048 ÷ 60 = 1 500 × 0.00508 = 7.62 m/s. **Context**: (a) typical commercial-jet climb below FL100; (b) about 0.77 g for the passenger (a gentle press into the seat, well below 1 g); (c) sea-level to 30 000 ft takes ~20 minutes ignoring step-climb speed limits. **Comparisons**: (a) an F-16 can hit 50 000 ft/min ≈ 254 m/s = 914 km/h (vertical aerobatic climb); (b) airline *maximum* climb rate (clean, light) tops out near 4 000 ft/min ≈ 20 m/s; (c) a glider riding a strong thermal climbs 200–600 ft/min (1–3 m/s) — a great day.
Are the scuba 9 m/min and 30 ft/min ascent-rate limits the same?
**Practically the same — difference < 2 %**. **Precisely**: 30 ft/min = 30 × 0.3048 = 9.144 m/min; 9 m/min = 9 ÷ 0.3048 = 29.53 ft/min. **Why agencies differ**: (a) NOAA / US Navy (1988 onward): *exactly* 30 ft/min (imperial culture); (b) PADI (post-1996): 18 m/min (more conservative); (c) 9 m/min is SSI / TDI guidance for the *final 10 m* after deep stops. **Key point**: slower is safer — slow ascent gives tissues time to off-gas dissolved nitrogen via respiration, lowering DCS (the bends) risk. **Modern dive computers** (Shearwater, Garmin Descent) display live ascent rate and flash if it is exceeded. **Emergency ascent** (air-out) is capped at 60 ft/min = 18 m/min, for emergencies only.
Which is faster — a 5 m/s elevator or a 1 000 ft/min one? How fast does a high-rise need?
**5 m/s is faster** by 1.6 %: 5 m/s = 984 ft/min ≈ 1 000 ft/min. **Design rules**: (a) **trip time = rise ÷ speed**, target *one-way* ≤ 30 s to top floor; (b) **acceleration** 0.6–1.2 m/s² (more is uncomfortable due to ear-pressure change); (c) **load** 1 350 kg standard commercial cab; (d) **wait interval** ≤ 30–35 s. **Typical speed vs rise**: (a) 6-storey residential 1.0 m/s (200 ft/min); (b) 20-storey commercial 2.5 m/s (500 ft/min); (c) 50-storey 5 m/s (1 000 ft/min); (d) 80-storey 8 m/s (1 600 ft/min); (e) super-tall like Burj Khalifa (163 floors) uses *double-deck* cabs + 18 m/s; (f) **world record**: Mitsubishi installation at Shanghai Tower runs 20.5 m/s (1 230 m/min = 4 035 ft/min) and climbs to floor 119 in 53 s. **Ear-pressure cliff**: > 3 m/s already discomforts some riders; super-tall systems use pressurised cabs (Burj uses active barometric balancing).
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Paste a JSON Web Token (JWT); the tool splits header.payload.signature per RFC 7519, Base64URL-decodes the first two segments into readable JSON, surfaces common claims (alg, typ, iss, sub, aud, exp, iat, nbf) and converts Unix timestamps to local dates — signature verification is intentionally out of scope; this is a debugging tool.
ppm / ppb / ppt ↔ Percent Concentration Converter
Convert concentration units: 1 % = 10 000 ppm = 10⁷ ppb = 10¹⁰ ppt. Enter any one and the tool fills in the other three; for dilute water solutions (density ≈ 1 g/mL) it also shows the equivalent mg/L (≈ ppm), µg/L (≈ ppb) and ng/L (≈ ppt) — useful for lab chemistry, water testing, food-safety standards and air-quality reference.
Color Temperature Mired Calculator (K ↔ Mired + CTO / CTB gel picker)
Enter two colour temperatures in Kelvin; the tool converts them to Mireds via M = 10⁶ ÷ K and uses the difference to recommend the nearest standard CTO (orange, warming) / CTB (blue, cooling) gel strength (Full, 1/2, 1/4, 1/8) — the working unit for photo, video and mixed-source lighting.
Egg Size Substitution Calculator
Recipe calls for 3 Large eggs but your fridge has Medium or Jumbo? Enter the recipe size and count, get the equivalent count for every other size (Small / Medium / Large / Extra Large / Jumbo) based on USDA standard weights, with whole eggs + part-egg whites / yolks to top up.
SMS Character & Segment Count Calculator
Paste your SMS message — the tool auto-detects GSM-7 vs UCS-2 encoding and returns character count and number of SMS segments (160/153 for GSM-7, 70/67 for UCS-2) so you can estimate sending cost.
LED Equivalent Wattage Calculator
Enter an incandescent bulb wattage (e.g. 60 W); using Energy Star's lumens-per-watt standards, the tool returns the equivalent LED watts, CFL watts and total lumens — useful when swapping out old bulbs.
Fresh ↔ Dried Herb Substitution Calculator
Enter fresh herb quantity (tsp / Tbsp / cup); using the industry 3 : 1 fresh-to-dried substitution rule, returns the dried equivalent. Reverses, includes 12 common herb defaults, and accepts a custom ratio.
Salt Volume Conversion (Kosher / Table / Sea) Calculator
Enter the recipe salt amount (tsp / tbsp / g / oz) and source type; the tool returns the equivalent volume in Diamond Crystal, Morton, table, sea and Maldon salt using Serious Eats / Cook's Illustrated bench-tested densities.
Climbing Grade Conversion Calculator (YDS / French / UIAA / V-scale / Font)
Enter a route or boulder grade in any one system; using the IFSC / UIAA / REI conversion table, simultaneously shows the equivalent in the other four common climbing grade systems.
Audio File Size (Bitrate × Duration) Calculator
Enter audio bitrate (kbps / Mbps) and duration (h / m / s); returns the resulting MP3 / AAC / WAV / FLAC file size in MB / GB, with common podcast and music encoding presets for quick reference.
Time Format Converter (Seconds ↔ HH:MM:SS)
Convert between seconds, minutes, hours and HH:MM:SS form — useful for video editing, sports timing and meeting durations.
Butter Unit Converter (Sticks / Grams / Tablespoons / Cups)
Baking butter conversions: enter any one quantity (sticks, grams, tablespoons or cups) and the tool returns the equivalent in the other three units.
Candy / Sugar Stage Temperature Reference Calculator
Enter syrup temperature (°C or °F) to instantly see the candy stage (thread / soft ball / firm ball / hard ball / soft crack / hard crack / light caramel / dark caramel), its full range and typical dessert use.
LED Display Pixel Pitch & Optimal Viewing Distance Calculator
Enter the LED panel pixel pitch (P-value, e.g. P2.5 / P4) plus screen width × height — get the effective resolution, pixel density and the minimum / comfortable / visual-fusion viewing distances so you size the right panel for any AV install.
Pixels Per Degree (PPD) VR / Display Calculator
Enter the horizontal / vertical pixel count and the corresponding field of view (FOV) — get the pixels-per-degree (PPD), the industry-standard metric for comparing VR headsets, monitors and TVs against the retinal-resolution benchmark (~60 PPD).
CSS Aspect Ratio Padding Calculator
Enter an aspect ratio (e.g. 16:9 or 16/9) — instantly get the padding-bottom percentage and matching CSS snippet (plus the modern aspect-ratio property), for responsive video / iframe containers.
RGB ↔ CMYK Color Converter
Enter RGB (0–255) and instantly get the CMYK percentage values (K, C, M, Y), with matching hex code and printing-friendly tips on the screen-sRGB → CMYK gamut gap.