Surface Albedo Reflected Radiation Calculator
Find how much sunlight a surface sends back: 800 W/m² on an albedo of 0.3 reflects 240 W/m² and absorbs 560 W/m². Albedos outside 0 to 1 are refused, so a percentage typed by mistake never slips through. Free in your browser.
- Free
- Runs in your browser
- No sign-up
- Your data stays on your device
Run — free
Worked example
- Incoming irradiance
- 800
- Albedo
- 0.3
- Reflected radiation
- 240
- Absorbed fraction
- 0.7
- Absorbed radiation
- 560
- Radiation unit
- W/m²
This surface albedo calculator converts incoming solar irradiance and a dimensionless albedo into reflected radiation, absorbed radiation, and the net absorbed fraction. It applies the standard surface energy split: reflected radiation equals incoming irradiance multiplied by albedo, while the remainder is absorbed. Use it for quick checks in climate science, solar-energy studies, building analysis, remote sensing, or environmental models. Inputs are explicit, results retain watts per square metre, and an albedo outside the physical range from zero to one is rejected instead of producing a misleading value.
Enter irradiance and albedo on compatible terms
Start with the solar irradiance that actually reaches the surface or layer you are studying, expressed in watts per square metre. This may be a measured shortwave flux, a modeled value, or a representative scenario, but it should refer to the same boundary at which the albedo applies. Then enter the surface albedo as a dimensionless decimal between zero and one.
An albedo of zero describes complete absorption with no reflected component, while an albedo of one describes complete reflection with no absorbed component. Values such as 0.20 or 0.65 represent twenty or sixty-five percent reflection. Do not enter a percentage such as 20 when you mean 0.20.
The calculator rejects negative irradiance, non-finite numbers, and albedo values outside the closed zero-to-one interval. This strict validation matters because a superficially plausible output based on an impossible albedo can quietly contaminate a larger energy budget, spreadsheet, simulation, or report.
Understand the reflected and absorbed results
The reflected radiation is calculated as incoming irradiance multiplied by albedo. The absorbed fraction is one minus albedo, and absorbed radiation is incoming irradiance multiplied by that fraction. Reflected and absorbed radiation therefore sum to the original incoming irradiance, apart from harmless numeric rounding.
For example, a darker surface has a lower albedo, reflects a smaller share, and absorbs a larger share; a brighter surface behaves in the opposite way. The returned radiation quantities use the same watts-per-square-metre basis as the incoming value, while albedo and absorbed fraction have no unit. This is a deliberately focused surface balance rather than a complete climate or thermal model.
It does not calculate outgoing longwave radiation, atmospheric absorption, transmission through a material, heat storage, convection, evaporation, temperature change, spectral dependence, or changes in the angle of the Sun. Those processes may be essential in a full energy budget, but they require additional observations and assumptions that are not implied by irradiance and albedo alone.
Use the calculation responsibly in larger models
Choose an albedo that matches the surface condition, wavelength range, and time scale of your incoming irradiance. Snow, soil, vegetation, roofs, pavement, clouds, and water can all have albedos that vary with moisture, age, illumination angle, season, surface roughness, and spectral band. A single broadband value is useful for screening and transparent scenario comparisons, but it should not be presented as a permanent material constant when conditions vary.
When comparing cases, keep the irradiance definition consistent and change only the assumptions you intend to test. Record the source of the albedo beside the result so another reader can reproduce the calculation. Because the algorithm is deterministic and performs no network lookup, identical numeric inputs always produce identical outputs.
That makes it suitable for automated validation, teaching examples, reproducible notebooks, and pipeline steps where an invalid physical range should stop processing rather than pass silently downstream.
What you can do with it
Compare land-cover scenarios
Estimate how replacing a dark surface with vegetation, snow, or a reflective material changes reflected and absorbed shortwave radiation.
Check a surface energy budget
Verify that reflected and absorbed components add back to the incoming irradiance before combining them with other energy flows.
Screen cool-roof assumptions
Compare the immediate solar absorption implied by candidate roof albedos under the same incident irradiance.
FAQ
What formula does the calculator use?
Reflected radiation equals incoming irradiance multiplied by albedo. The absorbed fraction equals one minus albedo, and absorbed radiation equals incoming irradiance multiplied by that fraction.
Should albedo be entered as a percentage?
No. Enter a decimal from 0 to 1. For example, enter 0.30 for an albedo of thirty percent.
What units are used for the radiation results?
Incoming, reflected, and absorbed radiation are expressed in watts per square metre (W/m²). Albedo and absorbed fraction are dimensionless.
Does this calculate surface temperature?
No. Temperature requires additional terms such as longwave emission, heat capacity, convection, evaporation, and time. This calculator covers only the reflected-versus-absorbed split of incoming solar irradiance.
What does an albedo of zero or one mean?
Zero means none of the incoming radiation is reflected by this simplified balance; one means all of it is reflected.
Related tools
For developers — API access
Everything on this page is available programmatically. This section is for teams who want to wire it into their own systems; everyone else can just use the tool above.
API endpoint
Prefer to automate it? One authenticated POST creates the task; the result comes back by webhook or a signed link. The same capability also runs here on the web, by email and from Telegram — and soon from our app too.
Call it from your stack
curl -X POST https://api.kit.forhosting.com/earth/albedo-reflected-radiation \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"incoming_irradiance":800,"albedo":0.3}'const res = await fetch("https://api.kit.forhosting.com/earth/albedo-reflected-radiation", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"incoming_irradiance": 800,
"albedo": 0.3
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/earth/albedo-reflected-radiation",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"incoming_irradiance": 800,
"albedo": 0.3
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/earth/albedo-reflected-radiation", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"incoming_irradiance":800,"albedo":0.3}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"incoming_irradiance":800,"albedo":0.3}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/earth/albedo-reflected-radiation", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"incoming_irradiance": 800,
"albedo": 0.3
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "earth.albedo_reflected_radiation",
"status": "queued",
"_links": {
"result": "/tasks/tsk_…/result"
}
}The API is asynchronous: the call returns a task_id immediately and the result arrives by webhook. Polling is capped at 1 req/s per task.
Pricing
Published price — no tokens, no invented credits. A failed task is never charged.
Errors
| HTTP | Code | Meaning |
|---|---|---|
401 | unauthorized | Missing or invalid API key. |
402 | insufficient_balance | Your balance doesn't cover the task price. |
404 | unknown_type | That task type doesn't exist. |
429 | rate_limited | Too many requests. Use the webhook instead of polling. |
Technical notes
Use the calculation responsibly in larger models
The API price is $0.002 per request, while the browser calculation can be used for direct checks.
Technical questions
What happens if albedo is outside the physical range?
The request returns an invalid-input error when albedo is below 0 or above 1, including when the value is not a finite number.