How many tie-down straps does your load need? Enter the cargo weight, the friction pairing, the lashing angle and your strap's standard tension force (STF, printed on the strap label), and get the EN 12195-1 top-over lashing count for forward and sideways/rearward restraint.
EN 12195-1 top-over lashing balances the sliding force against friction plus the vertical component of strap tension. Straps required per direction:
n ≥ (cx,y − μ) · m · g / (2 · μ · sin α · STF)
with road acceleration coefficients c = 0.8 forward and 0.5 sideways/rearward, g = 9.81 m/s², and STF in newtons (1 daN = 10 N). When μ ≥ c, friction alone restrains that direction — the standard and good practice still call for at least two tie-downs to keep the load stable.
Planning aid, not a substitute for the standard. The result assumes a rigid, non-tipping load on a flat bed with symmetric lashing. Tipping checks, direct lashing and rail/sea coefficients are outside this page. The driver and loader remain responsible for securing per EN 12195-1 and national rules; anti-slip mats (μ = 0.6) usually cut the required count dramatically.