How do I calculate soil loss with RUSLE?

Multiply the five factors: A = R × K × LS × C × P, with A in t/ha/yr. For R = 300, K = 0.03, LS = 2, C = 0.1 and P = 1, A = 1.80 t/ha/yr, which is 1606 lb/acre/yr and 0.14 mm of topsoil a year at a bulk density of 1.3 g/cm³. R, K, LS, C and P are the inputs; the tool does not look them up for a location.

What do the Low, Moderate, High and Very High classes mean?

They are fixed thresholds in this tool: Low below 5 t/ha/yr, Moderate below 10, High below 25 and Very High from 25. They are not a standard. Soil loss tolerance (T) values run from 1 to 5 tons per acre per year according to Wikipedia, which is 2.2 to 11.2 t/ha/yr, so a result in the Low class can still be above the tolerance of a soil whose T is 1.

How do I convert t/ha to lb/acre?

Multiply by 892.179. That is 1000 kg over 10,000 m² turned into pounds per acre, so 5 t/ha is 4461 lb/acre and 10 t/ha is 8922 lb/acre. The factor is arithmetic, not a figure from a table.

How is soil loss turned into millimeters of topsoil?

The tool divides the loss by the bulk density times 10: A ÷ (ρ × 10). At 1.8 t/ha/yr and 1.3 g/cm³ that is 0.14 mm a year. Bulk density must be between 0.5 and 2 g/cm³, and the default 1.3 is a working value, not a measurement of your soil.

What are the units of the K factor?

The tool takes K in metric units, t·h/(MJ·mm), from 0 to 0.1. Values given in US customary units (t·ac·h/(100 ft·tonf·in)) are multiplied by 0.1317 to convert, a factor a Stanford Natural Capital Project dataset attributes to Foster (1981). The tool does not suggest a typical K: take it from a soil survey for the site.

Does the calculator work out the LS factor from slope and slope length?

Yes, if you enter both the slope in percent (0 to 100) and the slope length (0.1 to 1,000 m or 0.3 to 3,300 ft). It applies the RUSLE equations of McCool and others as given in Agriculture Handbook 703 (Renard et al. 1997): a 10 % slope 100 m long gives L = 2.184, S = 1.1717 and LS = 2.559. Under 4.572 m (15 ft) it uses the short-slope equation S = 3.0 sin^0.8 θ + 0.56. Clear both slope fields to type LS yourself, from 0 to 100. It shows a warning for LS above 30 and for R above 5000, as a prompt to recheck the value, not as a limit.

Soil Erosion Rate Calculator

Annual soil loss in t/ha/yr and lb/acre/yr from RUSLE, A = R × K × LS × C × P, with topsoil mm/yr and a Low to Very High class. How it works

Display Units:

R — Rainfall Erosivity

MJ·mm/(ha·h·yr). Look up from a regional erosivity map.

K — Soil Erodibility

Metric units, t·h/(MJ·mm). US customary values (t·ac·h/(100 ft·tonf·in)) are multiplied by 0.1317 to convert (Foster 1981).

Slope steepness (%, optional)

With the slope length, LS is worked out for you (McCool et al.; Renard et al. 1997, Agriculture Handbook 703). Clear both to type LS yourself.

Slope length (m, optional)

Horizontal length from where runoff starts to where it deposits or reaches a channel.

LS — Slope Length & Steepness

Dimensionless combined factor. Type it, or enter the slope and slope length above to have it worked out (McCool et al. equations).

C — Cover-Management

0 = full ground cover. 1 = bare soil. Lower is better.

P — Conservation Practice

0 = maximum conservation. 1 = no practice. Lower is better.

Predicted Annual Soil Loss

0.30 t/ha/yr

Topsoil Lost 0.02 mm/yr · Soil loss, imperial 268 lb/acre/yr

Low

Low: under 5 t/ha/yr on this scale.

The class uses fixed thresholds of 5, 10 and 25 t/ha/yr, not your soil's tolerance. NRCS soil-loss tolerance (T) values run from 1 to 5 US tons/ac/yr, which is 2.2 to 11.2 t/ha/yr (metric tonnes); a soil with a lower T tolerates less loss.

Factor Breakdown

Factor	Value	Cumulative
R	100	100
K	0.03	3
LS	1	3
C	0.1	0.3
P	1	0.3
A	—	0.30 t/ha/yr

Formula: A = R × K × LS × C × P (RUSLE).

Source: Renard et al. (1997). USDA Agricultural Handbook 703.

LS from slope: L = (λ ÷ 22.13 m)^m with m = β ÷ (1 + β) and β = (sin θ ÷ 0.0896) ÷ (3.0 sin^0.8 θ + 0.56); S = 10.8 sin θ + 0.03 for slopes under 9 %, 16.8 sin θ − 0.50 from 9 %, and 3.0 sin^0.8 θ + 0.56 when the slope length is under 4.572 m (15 ft). λ is the horizontal slope length; this page accepts slopes up to 100 % and lengths up to 1,000 m.

This calculator predicts sheet and rill erosion only. Gully, streambank, and ephemeral gully erosion are out of scope.

RUSLE assumes unfrozen soil.

About the Soil Erosion Rate Calculator

With R = 100, K = 0.03, LS = 1, C = 0.1 and P = 1, RUSLE gives 0.30 t/ha/yr of soil loss, which is 268 lb/acre/yr and 0.02 mm of topsoil a year. The soil erosion calculator multiplies the five factors, A = R × K × LS × C × P, and labels the result Low below 5 t/ha/yr, Moderate below 10, High below 25 and Very High above that. Those thresholds are the tool’s own, not a soil’s tolerance.

What the cover factor does: R 300, K 0.03, LS 2, P 1

Cover factor C	Soil loss (t/ha/yr)	lb/acre/yr	Topsoil (mm/yr)	Class
1	18.00	16059	1.38	High
0.5	9.00	8030	0.69	Moderate
0.1	1.80	1606	0.14	Low
0.01	0.18	161	0.01	Low
0.001	0.02	16	0.00	Low

C = 1 is bare soil. The factors are illustrative inputs, not site data: take R, K, LS, C and P from a source for your location.

The loss classes in other units

Class boundary	Soil loss (t/ha/yr)	lb/acre/yr	Topsoil at 1.3 g/cm³ (mm/yr)
Low ends below	5	4461	0.38
Moderate ends below	10	8922	0.77
High ends below	25	22304	1.92

The thresholds of 5, 10 and 25 t/ha/yr are fixed in the tool and are not tied to a soil’s tolerance. 1 t/ha = 892.179 lb/acre.

LS factor by slope and slope length

Slope	10 m	22.13 m (72.6 ft)	50 m	100 m	200 m
2%	0.2026	0.246	0.3001	0.3554	0.4209
5%	0.414	0.5693	0.7894	1.042	1.376
10%	0.7765	1.172	1.787	2.559	3.664
15%	1.259	1.992	3.189	4.759	7.101
20%	1.716	2.795	4.611	7.057	10.8
30%	2.566	4.327	7.399	11.68	18.42

RUSLE equations of McCool and others as given in Renard et al. (1997), Agriculture Handbook 703: L = (λ ÷ 22.13 m)^m with m = β ÷ (1 + β) and β = (sin θ ÷ 0.0896) ÷ (3.0 sin^0.8 θ + 0.56); S = 10.8 sin θ + 0.03 under 9 % and 16.8 sin θ − 0.50 from 9 %. The slope length is horizontal. 22.13 m is the length of the standard plot, where L = 1.

How to use this tool

Enter R, K, LS, C and P. For LS you can instead enter the slope in percent and the slope length in m or ft, and the tool fills in LS. A blank or out-of-range entry shows a message with the allowed range, and no result until it is fixed.
Choose metric (t/ha/yr) or imperial (lb/acre/yr) for the headline figure.
Open Show Advanced to change the bulk density that turns tons per hectare into millimeters of topsoil. Read the class label, then the factor table to see how each factor changes the running product.

Frequently asked questions

How do I calculate soil loss with RUSLE?: Multiply the five factors: A = R × K × LS × C × P, with A in t/ha/yr. For R = 300, K = 0.03, LS = 2, C = 0.1 and P = 1, A = 1.80 t/ha/yr, which is 1606 lb/acre/yr and 0.14 mm of topsoil a year at a bulk density of 1.3 g/cm³. R, K, LS, C and P are the inputs; the tool does not look them up for a location.
What do the Low, Moderate, High and Very High classes mean?: They are fixed thresholds in this tool: Low below 5 t/ha/yr, Moderate below 10, High below 25 and Very High from 25. They are not a standard. Soil loss tolerance (T) values run from 1 to 5 tons per acre per year according to Wikipedia, which is 2.2 to 11.2 t/ha/yr, so a result in the Low class can still be above the tolerance of a soil whose T is 1.
How do I convert t/ha to lb/acre?: Multiply by 892.179. That is 1000 kg over 10,000 m² turned into pounds per acre, so 5 t/ha is 4461 lb/acre and 10 t/ha is 8922 lb/acre. The factor is arithmetic, not a figure from a table.
How is soil loss turned into millimeters of topsoil?: The tool divides the loss by the bulk density times 10: A ÷ (ρ × 10). At 1.8 t/ha/yr and 1.3 g/cm³ that is 0.14 mm a year. Bulk density must be between 0.5 and 2 g/cm³, and the default 1.3 is a working value, not a measurement of your soil.
What are the units of the K factor?: The tool takes K in metric units, t·h/(MJ·mm), from 0 to 0.1. Values given in US customary units (t·ac·h/(100 ft·tonf·in)) are multiplied by 0.1317 to convert, a factor a Stanford Natural Capital Project dataset attributes to Foster (1981). The tool does not suggest a typical K: take it from a soil survey for the site.
Does the calculator work out the LS factor from slope and slope length?: Yes, if you enter both the slope in percent (0 to 100) and the slope length (0.1 to 1,000 m or 0.3 to 3,300 ft). It applies the RUSLE equations of McCool and others as given in Agriculture Handbook 703 (Renard et al. 1997): a 10 % slope 100 m long gives L = 2.184, S = 1.1717 and LS = 2.559. Under 4.572 m (15 ft) it uses the short-slope equation S = 3.0 sin^0.8 θ + 0.56. Clear both slope fields to type LS yourself, from 0 to 100. It shows a warning for LS above 30 and for R above 5000, as a prompt to recheck the value, not as a limit.

Important limitations

RUSLE estimates a long-term average annual soil loss from the factors you supply, so the result is only as good as R, K, LS, C and P. It says nothing about a single storm, gully or stream-bank erosion, or where the soil ends up. The tool accepts R from 0 to 10,000, K from 0 to 0.1, LS from 0 to 100, C and P from 0 to 1, and a bulk density from 0.5 to 2 g/cm³. LS from slope treats the field as one uniform slope of that steepness and length.

Sources

Last reviewed: 2026-10-22

Comparing erosion scenarios

With R = 300, K = 0.03 and LS = 2, bare soil (C = 1) loses 18.00 t/ha/yr while a cover factor of 0.1 loses 1.80, a tenth as much. Because RUSLE is a straight product, halving any one factor halves the loss, so a farmer weighing a cover crop or reduced tillage against bare soil, or a planner comparing land uses on the same slope, can change C or P alone and read the difference in t/ha/yr, lb/acre/yr and millimeters of topsoil.

The RUSLE formula

A = R × K × LS × C × P

A is the average annual soil loss in t/ha/yr. R is rainfall erosivity in MJ·mm/(ha·h·yr), from 0 to 10,000. K is soil erodibility in t·h/(MJ·mm), from 0 to 0.1; US customary values are multiplied by 0.1317 to convert. LS, the slope-length and steepness factor from 0 to 100, is typed or worked out from the slope in percent and its length with the RUSLE equations of McCool and others (Renard et al. 1997): L = (λ ÷ 22.13 m)^m, and S = 10.8 sin θ + 0.03 under 9 % or 16.8 sin θ − 0.50 from 9 %. A 10 % slope 100 m long gives L = 2.184, S = 1.1717 and LS = 2.559. C is the cover-management factor and P the conservation-practice factor, each from 0 (full protection) to 1 (none).

lb/acre/yr = A × 892.179 and topsoil mm/yr = A ÷ (bulk density × 10), with a bulk density of 1.3 g/cm³ unless you change it.

Example: R = 100, K = 0.03, LS = 1, C = 0.1, P = 1 gives A = 0.30 t/ha/yr, 268 lb/acre/yr and 0.02 mm/yr.

The class labels use fixed thresholds of 5, 10 and 25 t/ha/yr, not a soil’s tolerance; NRCS T values run from 1 to 5 tons per acre a year, or 2.2 to 11.2 t/ha.

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Use the Soil Erosion Rate Calculator

Factor Breakdown

About the Soil Erosion Rate Calculator

What the cover factor does: R 300, K 0.03, LS 2, P 1

The loss classes in other units

LS factor by slope and slope length

How to use this tool

Frequently asked questions

Comparing erosion scenarios

The RUSLE formula

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