Nine out of ten ramp enquiries we receive in Foshan are ordered the wrong way round. The buyer picks a budget and a capacity in tonnes, then asks whether the ramp will reach their trailers. Length is the last thing decided — and the only dimension that cannot be fixed later. A ramp 1 m (3’3″) too short is not a discount; it is a machine your forklift cannot climb with a load.
Here is the calculation we run with customers before any drawing is issued.
Two Numbers Decide the Ramp, Not the Catalogue
Everything comes down to these:
- The rise — the vertical distance the ramp has to climb. For ground-to-trailer loading, that is the trailer bed height above the ground where the ramp foot will stand. Not the dock height, not the trailer’s nominal floor height: the actual measured height of the bed at the loading door, with the trailer at ride height and loaded to roughly the weight it will carry.
- The grade — how steep you are willing to let the working slope be, expressed either as a percentage or as an angle. This is a decision, not a measurement, and it is where most buyers get talked into a mistake.
Once you have those two, the length is arithmetic:
Ramp length = rise ÷ grade
With the grade written as a decimal. A 1,270 mm (50 in) rise at a 12.5% grade needs 1,270 ÷ 0.125 = 10,160 mm, or about 10.2 m (33’4″). Same rise at 16% needs 7,940 mm (26’1″). You did not change the job — you changed the decision, and the ramp got 2.2 m shorter and noticeably steeper.
The Formula Is Easy. Choosing the Grade Is Not.
Two standards get quoted constantly in this discussion, and both are usually quoted wrongly.
In Europe, EN 1398 governs dock levellers and limits the working gradient to ±12.5%, about 7°. But EN 1398 is a dock leveller standard — it does not govern a portable ramp standing in a yard, and treating 12.5% as a legal ceiling for portable ramps is a misreading.
In North America, ANSI MH30.1 covers dock leveling devices and ANSI MH30.2 covers portable dock leveling devices — dock plates and dock boards. These sit alongside OSHA 29 CFR 1910.178, which regulates how powered industrial trucks are operated.
The clause that actually matters to your layout is OSHA 1910.178(n)(7)(i): when ascending or descending grades in excess of 10 percent, loaded trucks must be driven with the load upgrade. In plain terms, above 10% your operator has to climb with the load facing uphill, no exceptions, in both directions. That is an operating rule and it is not optional. If your ramp runs at 15%, every loaded trip on it is governed by that clause — so the ramp grade is not purely a comfort question, it changes your traffic pattern and your training.
The honest engineering position is this: for a portable yard ramp, the binding limit is the forklift’s loaded gradeability, with margin. A counterbalance forklift that advertises 20% gradeability empty may only hold 12–14% with a full-rated load at full lift height. Ask your forklift dealer for the loaded figure, or stay at or below 12.5% and accept the extra length.
Two practical rules we give customers:
- Forklift, loaded: 10–14% is workable. Below 10% you avoid the load-upgrade rule entirely, which simplifies training.
- Manual pallet truck: 8% or less. A person pushing a 1,000 kg (2,200 lb) pallet up more than 8% is a fatigue and injury case waiting to be written.
Trailer Bed Heights You Will Actually Meet
Now the first number. Do not trust a specification sheet from the trailer manufacturer — bed height changes with load, suspension setting and tyre condition. These are the ranges we see repeatedly in export orders, and they are a starting point for measurement, not a substitute for it.
| Vehicle / situation | Bed height above ground | Notes |
|---|---|---|
| Drop-deck trailer | 1,020 mm / 40.2 in (3’4″) | Lowest common case; needs the shortest ramp |
| Standard dock height (US) | 1,220 mm / 48.0 in (4’0″) | The reference height for dock equipment |
| 53 ft dry van, loaded | 1,220–1,270 mm / 48–50 in (4’0″–4’2″) | Most common import/export case |
| Container on a chassis | 1,140–1,350 mm / 44.9–53.1 in (3’9″–4’5″) | Varies widely by chassis type — measure it |
| Refrigerated trailer | 1,270–1,400 mm / 50–55 in (4’2″–4’7″) | Thicker insulated floor pushes the bed up |
| Flatbed deck | 1,520 mm / 59.8 in (5’0″) | The tallest common case |
| Container standing on the ground | 150–180 mm / 5.9–7.1 in (0’6″–0’7″) | Door sill height only — see the container ramp note below |
If your site serves more than one of these, size for the highest one. A ramp that reaches a 1,520 mm (5’0″) flatbed will also reach a 1,220 mm (4’0″) van — it just runs at a gentler grade. A ramp sized for the van and then used on the flatbed will be over its working angle and, in most cases, over its safe angle.
Ramp Length Cheat Sheet
Here is the calculation pre-run for the four most common rises and five common grades. Lengths are rounded to the nearest 10 mm.
| Rise to cover | @ 10% | @ 12.5% | @ 14% | @ 16% |
|---|---|---|---|---|
| 1,220 mm / 48 in | 12,200 mm (40’0″) | 9,760 mm (32’0″) | 8,710 mm (28’7″) | 7,620 mm (25’0″) |
| 1,270 mm / 50 in | 12,700 mm (41’8″) | 10,160 mm (33’4″) | 9,070 mm (29’9″) | 7,940 mm (26’1″) |
| 1,400 mm / 55 in | 14,000 mm (45’11”) | 11,200 mm (36’9″) | 10,000 mm (32’10”) | 8,750 mm (28’8″) |
| 1,520 mm / 60 in | 15,200 mm (49’10”) | 12,160 mm (39’11”) | 10,860 mm (35’8″) | 9,500 mm (31’2″) |
Look at the left-hand column and you can see the real cost of a gentle slope. Covering a 1,520 mm (60 in) flatbed at 10% needs a ramp over 15 m (49’10”) long — a 15 m object to store, tow and load into a container. That is why most 10–15 t yard ramps in the market sit in the 12–15% band: it is the compromise between safety margin and a machine you can actually move.
Percent or Degrees — and What Each Grade Feels Like
Engineers quote percent, operators think in degrees. The conversion is not linear as people assume: 12.5% is not “12.5 degrees”, it is about 7.1°.
| Grade | Angle | What it means in practice |
|---|---|---|
| 8% | 4.6° | Comfortable for manual pallet trucks and electrically powered pallet trucks |
| 10% | 5.7° | The OSHA load-upgrade threshold — above this the rule bites |
| 12.5% | 7.1° | EN 1398 limit for dock levellers; a sensible target for portable ramps |
| 14% | 8.0° | Typical working grade on a 10 t mobile yard ramp |
| 15% | 8.5° | Upper end of normal for counterbalance forklifts with light loads |
| 16% | 9.1° | Achievable but demanding; check loaded gradeability before ordering |
| 20% | 11.3° | Specialised low-profile ramps only, usually short and unloaded use |
Slope Is Only Half the Story: Breakover, Clearance and the Lip
Length alone does not make a ramp usable. Four details cause more field complaints than the angle ever does.
Breakover at the ramp foot. The transition from flat ground onto the incline is a sharp intersection on a single-piece ramp, and a forklift with a low chassis or a long wheelbase can ground out there. Rounded entry plates, or a longer approach plate at the toe, fix it — but they must be specified at order, not welded on later.
Underside clearance. Deck thickness, side beams and cylinder position all sit under the running surface, and the highest point of the underside is a real constraint for low-clearance equipment. Tell us the machine’s ground clearance and we will confirm it in the drawing.
Lip length and overlap. The lip is the short plate that lands on the trailer bed. It must land with meaningful overlap, not a token landing. Standard practice on our ramps is a lip of roughly 400–500 mm (15.7–19.7 in), and the overlap should be checked against the shortest trailer you will serve — a short landing can walk off the bed under a loaded forklift.
Deck width. A 2,100 mm (6’11”) deck feels generous until a 1,800 mm (5’11”) wide load arrives with no margin. For forklifts carrying wide pallets, 2,300–2,400 mm (7’7″–7’10”) is the safer order and costs far less than a retrofit.
Standard Lengths We Build — and What Each One Covers
Here is what each standard ramp length reaches at each working grade. Pick the row that covers your tallest trailer, then round up.
| Ramp length | Reaches @ 10% | Reaches @ 12.5% | Reaches @ 14% | Reaches @ 16% |
|---|---|---|---|---|
| 7,500 mm / 24’7″ | 750 mm (2’6″) | 940 mm (3’1″) | 1,050 mm (3’5″) | 1,200 mm (3’11”) |
| 9,000 mm / 29’6″ | 900 mm (2’11”) | 1,120 mm (3’8″) | 1,260 mm (4’2″) | 1,440 mm (4’9″) |
| 10,500 mm / 34’5″ | 1,050 mm (3’5″) | 1,310 mm (4’4″) | 1,470 mm (4’10”) | 1,680 mm (5’6″) |
| 12,000 mm / 39’4″ | 1,200 mm (3’11”) | 1,500 mm (4’11”) | 1,680 mm (5’6″) | 1,920 mm (6’4″) |
| 13,500 mm / 44’3″ | 1,350 mm (4’5″) | 1,690 mm (5’7″) | 1,890 mm (6’2″) | 2,160 mm (7’1″) |
The reading is straightforward. A 12,000 mm (39’4″) hydraulic ramp at a 12.5% working grade covers a 1,500 mm (4’11”) rise — enough for a loaded reefer or a container on most chassis, with the legs of a flatbed left to the 13,500 mm unit. A 9,000 mm (29’6″) ramp covers dry vans comfortably at 14% and nothing taller.
As a guide, a 10 t (22,000 lb) standard hydraulic mobile yard ramp in a 10,500 mm length typically lists in the USD 4,800–6,200 EXW range, a 15 t (33,000 lb) heavy-duty unit around USD 6,500–8,500, and a 20 t (44,000 lb) electro-hydraulic ramp USD 9,500–12,500. Indicative 2026 EXW Foshan ranges for standard sizes, not a quotation; length, deck width and finish all move the figure.
When a Longer Ramp Is the Wrong Answer
Longer is not automatically safer. Three cases where the right move is to stop adding length:
Containers on the ground. A container standing on the ground has a door sill only 150–180 mm (5.9–7.1 in) above grade. At a 12.5% grade that needs 1.2–1.4 m of ramp — but what you actually need is a short, wide, very strong plate. Our HRCN-A container ramp at 6 t (13,200 lb) exists exactly for this, and it costs a fraction of a yard ramp because it is not trying to solve a problem that does not exist.
Fixed operating points. If a ramp is going to live at one door for five years and the trailer mix is stable, a fixed loading ramp or a dock ramp platform with an integrated leveler gives a permanent, wider running surface, and frees your floor from a towable machine.
Tight yards. Two-piece folding ramps solve the length-versus-storage conflict: a 12,000 mm ramp folds to roughly half its working length for transport and storage, then unfolds to the full geometry in use. If your constraint is turning radius rather than slope, this is the answer — not a shorter ramp at a steeper grade.
Five Numbers to Send Before We Quote
- Measured rise in mm or inches, ground to the highest trailer bed you will serve.
- Forklift model, tyre type and the actual load you will lift — not the forklift’s rated capacity.
- Trailer list or at least the shortest and tallest vehicles that will use the ramp.
- Ground surface and location — concrete, asphalt or gravel, indoors or outdoors, coastal or salted.
- Deck width requirement, driven by the widest load or pallet you handle.
With those five, the length falls out of one line of arithmetic, and we can confirm the working grade in percent and degrees before you commit to anything.
Frequently Asked Questions
How do I calculate the ramp length I need?
Divide the rise by the grade. If your trailer bed is 1,270 mm (50 in) above the ground and you accept a 14% working grade, you need 1,270 ÷ 0.14 = 9,070 mm, about 9.1 m (29’9″). Round up to the next standard length — in our range that is 10,500 mm (34’5″), which brings the actual grade down and gives you margin.
Is 12.5% the maximum legal slope for a loading ramp?
No. The 12.5% figure comes from EN 1398, which governs permanently installed dock levellers in Europe, and it caps the working gradient at ±12.5% (about 7°). It does not set a legal limit for portable yard ramps. For portable ramps the practical limit is your forklift’s loaded gradeability, with OSHA 29 CFR 1910.178(n)(7)(i) requiring loaded trucks to travel with the load upgrade on grades over 10%.
What is the steepest ramp a forklift can climb?
That is a property of the forklift, not the ramp. Counterbalance forklifts commonly advertise 15–20% gradeability, but gradeability is typically quoted empty; loaded figures are much lower. A safe working assumption for planning is 10–14% for a loaded counterbalance forklift, and 8% or below if manual pallet trucks will use the ramp.
Does a longer ramp always mean a safer ramp?
It means a gentler slope, which is generally safer, but it also means more weight, more storage space and a harder machine to tow into position. For containers on the ground, a long ramp is the wrong answer entirely. Match the ramp to the rise and the vehicle mix rather than defaulting to the longest option.
Get the Length Confirmed Before You Buy
Send us your measured rise, your forklift model with its load, and the list of trailers the ramp must serve. We will come back with the recommended length, the resulting working grade in both percent and degrees, and a drawing showing breakover and underside clearance. If a shorter, cheaper product does the job — a container ramp or a dock plate — we will say so.
Ask for a sizing check and dimensional drawing on our contact page, or review the standard models first: the HRYS 10 t standard hydraulic mobile yard ramp, the HRHS 15 t heavy-duty hydraulic yard ramp, and the full mobile yard ramp and portable dock ramp ranges.
