Daily fluid need
API · /hydration-api
Hydration Calculator API
healthy
4,678 Subscribers
Hydration and fluid-balance maths as an API, computed locally and deterministically. The daily endpoint estimates the daily fluid need from bodyweight (about 35 ml per kilogram), the minutes of exercise (about 12 ml per minute) and the climate (hot adds 500 ml, very hot 1000 ml, cold subtracts 200 ml), reported in millilitres, litres and 250 ml glasses. The sweat endpoint computes the sweat rate and the degree of dehydration from a before-and-after body weight, the fluid drunk and the duration — sweat loss = (pre − post) + intake − urine, with 1 kg of lost mass treated as 1 litre, and it flags when losses pass the 2 % of body mass where performance falls off. The rehydrate endpoint computes the post-exercise rehydration target, about 1.5 times the fluid deficit to cover ongoing urine losses, with a sodium note for larger losses. Everything is computed locally and deterministically, so it is instant and private. Ideal for fitness, sports and wellness app developers, endurance-training and hydration-reminder tools, and health dashboards. Pure local computation — no key, no third-party service, instant. Live, nothing stored. General guidance, not medical advice. 3 endpoints. This is fluid balance; for basal calories use a BMR API and for heart-rate zones use a heart-rate API.
api.oanor.com/hydration-api
API health
healthy- Uptime
- 100.00%
- Server probes · 24h
- Avg latency
- 74 ms
- Server probes · 24h
- Subscribers
- 4,678
- active
- Total calls
- 76
- last 7 days
Pricing
Pick a tier — billed monthly, cancel anytime.
Free
Free
- 3,000 calls / month
- 2 requests / second
- Hard cap (429 above quota, no overage)
- Daily fluid-need estimate from bodyweight
- Single-athlete sweat-rate calc
- Metric and imperial units
- Community support
Starter
€4.00 /month
- 40,000 calls / month
- 5 requests / second
- Hard cap (429 above quota, no overage)
- Full daily + sweat-rate endpoints
- Activity and climate adjustment factors
- Electrolyte replacement hints
- Email support
Pro
€12.00 /month
- 250,000 calls / month
- 15 requests / second
- Hard cap (429 above quota, no overage)
- High-volume hydration scoring
- Session-by-session fluid-loss tracking
- Batch athlete calculations
- Priority support
Mega
€39.00 /month
- 1,516,000 calls / month
- 40 requests / second
- Hard cap (429 above quota, no overage)
- Bulk hydration planning at scale
- Team and fleet fluid-balance workloads
- Highest rate limits
- Dedicated support SLA
Built by
Related APIs
Other APIs with overlapping tags.
Swimming API
Swimming maths as an API, computed locally and deterministically — the SWOLF, threshold-pace and per-100 m numbers a swimmer, coach or training app works a set out with. The swolf endpoint scores stroke efficiency for one length: SWOLF (swim + golf) = the strokes taken plus the seconds taken, and like golf lower is better — gliding further per stroke or swimming faster both cut it, so a 25 m length in 18 strokes and 30 s is a SWOLF of 48. Because it is pool-length and stroke dependent, the score is normalized to 25 m so lengths in different pools compare. The css endpoint computes Critical Swim Speed, the swimmer's threshold pace, from two all-out time trials: CSS = (distance1 − distance2) ÷ (time1 − time2) — the classic 400 m and 200 m test, where 6:00 and 2:50 give about 1.05 m/s, a 1:35 / 100 m threshold; training paces are then set as offsets from CSS, the swimmer's equivalent of a runner's threshold or an erg's 2 k pace. The pace endpoint gives speed and the per-100 m pace swimmers actually quote (time ÷ distance × 100), so 100 m in 1:30 is a 1:30 / 100 m pace at 1.11 m/s. Everything is computed locally and deterministically, so it is instant and private. Ideal for swim-training and coaching tools, lap-tracker and triathlon apps, and fitness calculators. Pure local computation — no key, no third-party service, instant. 3 compute endpoints. For running pace use a pace API; for indoor rowing a rowing API.
api.oanor.com/swimming-api
Indoor Rowing API
Indoor-rowing (Concept2 erg) maths as an API, computed locally and deterministically — the watts, split and calorie numbers a rower, coach or fitness app works a piece out with, using the published Concept2 relations. The split-to-watts endpoint turns a 500 m split into power: on an erg the power is fixed by the pace, not the stroke rate, so watts = 2.80 ÷ pace³ where the pace is the seconds per metre (the split ÷ 500) — a 2:00 split is about 202 W. Because power goes as the inverse cube of pace, small split gains cost a lot of watts: pulling 1:50 instead of 2:00 is roughly 270 W, not 220. The watts-to-split endpoint inverts it — pace = (2.80 ÷ watts)^(1/3), split = pace × 500 — so a target wattage maps to the split on the monitor and a rower's power compares directly with a cyclist's or any other watts figure. The calories endpoint applies the Concept2 calorie formula, Cal/hr = (watts × 4 × 0.8604) + 300, where the +300 is a fixed resting-metabolism term that makes the erg's count run higher than pure mechanical work; 200 W is about 988 Cal/hr, roughly 494 calories over 30 minutes. Everything is computed locally and deterministically, so it is instant and private. Ideal for rowing and erg training tools, coaching and leaderboard apps, and fitness calculators. Pure local computation — no key, no third-party service, instant. Concept2 model — a machine estimate, not lab calorimetry. 3 compute endpoints. For running pace use a pace API; for cycling a cycling API.
api.oanor.com/rowing-api
Powerlifting Score API
Powerlifting strength-score maths as an API, computed locally and deterministically — the Wilks, DOTS and IPF GL numbers a meet, gym or training app uses to compare lifters across bodyweights and sexes. The wilks endpoint gives the classic Wilks coefficient (1996) and score: total × 500 ÷ a fifth-order polynomial in bodyweight, with separate male and female curves — long the federation standard for "best lifter", a 100 kg man totalling 600 kg scores about 365. The dots endpoint gives the modern DOTS score (2019), the same total × 500 ÷ polynomial idea but fitted to updated data with a fourth-order curve that is fairer across the weight classes and not skewed to the middleweights, now the default in most raw meet software. The ipf-gl endpoint gives the International Powerlifting Federation's current GL Points (2020): 100 × total ÷ (A − B·e^(−C·bodyweight)), with separate constants for sex and for raw (classic) versus equipped lifting, the official metric at IPF championships. Everything is computed locally and deterministically, so it is instant and private. Ideal for meet-management and scoring software, gym leaderboards and training-log apps, and strength-sport tools. Pure local computation — no key, no third-party service, instant. 3 compute endpoints. For one-rep-max estimation and plate loading use a strength-training API.
api.oanor.com/powerlifting-api
Barbell & Lifting API
Barbell and weight-training maths as an API, computed locally and deterministically — the plate-loading and percentage numbers a lifter, coach or gym app works out at the rack. The plates endpoint solves the everyday gym puzzle of which plates go on each side for a target weight: 100 kg on a standard 20 kg bar means 40 kg a side, loaded heaviest first as a 25 and a 15; 102.5 kg adds the 1.25 micro-plate; and if a target is not reachable with the plates on hand it loads the closest it can and tells you the shortfall, so you never guess. It works in kilograms or pounds (225 lb on a 45 lb bar is two 45s a side), with a custom bar weight and a custom plate set. The percent endpoint turns a one-rep-max into the working weight you actually load: 80 % of a 100 kg max is 80 kg, and asking for a five-rep weight returns about 85.7 kg via the Epley formula (1RM = weight × (1 + reps ÷ 30)) — five reps sits near 86 % of max, ten reps near 75 %. The warmup endpoint builds a ramp from the empty bar to the working set at roughly 40, 55, 70 and 85 %, each rounded to a loadable increment, with the rep count dropping as the bar gets heavy. Everything is computed locally and deterministically, so it is instant and private. Ideal for gym, strength-training, powerlifting and fitness app developers, workout-logger and coaching tools, and smart-rack and plate-calculator builders. Pure local computation — no key, no third-party service, instant. Exact maths, no simulation. Live, nothing stored. 3 compute endpoints. For one-rep-max estimation from a set use a strength API.
api.oanor.com/barbell-api
Frequently asked questions
Quick answers about pricing, quotas, and integration.
How do I get an API key for Hydration Calculator API?
Sign up for free at oanor.com, generate an API key from the developer dashboard, and call Hydration Calculator API with the x-oanor-key header. No credit card needed for the free tier.
What's the rate limit for Hydration Calculator API?
Free tier allows 1 request per second. Paid plans scale up to 50 requests per second on the Mega tier. Hard limits return HTTP 429 above the quota — no surprise overage charges.
How much does Hydration Calculator API cost?
Hydration Calculator API has a free tier with 100 calls / month. Paid plans start at €4.00 / month with higher quotas and faster rate limits.
Can I cancel my subscription anytime?
Yes. Plans are billed monthly and you can cancel anytime from your billing dashboard. No long-term contracts and no cancellation fee.
Is Hydration Calculator API GDPR-compliant?
All requests to Hydration Calculator API go through our EU-based gateway. Your upstream API key never leaves our server and no personal data is shared with the upstream provider beyond the request you send.
Pick an endpoint from the list on the left to see its details and try it.
Code snippets
Sign up to get an API key, then call any path under your slug.
curl https://api.oanor.com/hydration-api/SOME_PATH \
-H "x-oanor-key: oanor_test_..."const res = await fetch("https://api.oanor.com/hydration-api/SOME_PATH", {
headers: { "x-oanor-key": "oanor_test_..." }
});
const data = await res.json();$ch = curl_init("https://api.oanor.com/hydration-api/SOME_PATH");
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, ["x-oanor-key: oanor_test_..."]);
$response = curl_exec($ch);import requests
r = requests.get(
"https://api.oanor.com/hydration-api/SOME_PATH",
headers={"x-oanor-key": "oanor_test_..."},
)
print(r.json())Ratings
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